Estradiol vs Estriol: What's Actually Different, and Which One Fits You?
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Estradiol vs estriol comes down to evidence, route, dose, and regulatory status—not a simple “stronger versus gentler” choice. In the United States, FDA-approved estradiol products exist for systemic and vaginal use; no human estriol drug is FDA-approved. For an E2-versus-E3 choice, systemic menopause treatment points to approved estradiol options, while estriol's clearest direct evidence is ultra-low-dose vaginal treatment.
Last verified: September 2026 · Editorial research—not medical advice, and not reviewed by a clinician · By The HRT Index Editorial Team
Some links on this page may be affiliate links, and The HRT Index may earn a commission if you use them. It never changes what we publish—including on this page, where a partner's compounded product is criticized by name. Read our full disclosure.
Best for / not for you if
- Estradiol is the clearer starting point if you want an FDA-approved option for hot flashes, night sweats, sleep disruption driven by those symptoms, bone-loss prevention, vaginal dryness, or painful sex—and you want a finished product with an approved label and product-specific dosing information.
- Estriol is worth a real conversation if your main problem is vaginal dryness or painful sex, an approved estriol product is available where you live, or a clinician has a specific reason to request a patient-specific compounded formulation in the U.S.
- Do not choose either one from a generic online intake alone if you have unexplained vaginal bleeding or any bleeding after menopause. A history of an estrogen-dependent cancer also needs a specialist-involved decision, not a one-size-fits-all sales funnel.
- The number that decides most U.S. comparisons: there are zero FDA-approved estriol drugs for humans in the United States. That does not make estriol fake or automatically illegal. It means the finished human estriol products sold here are not FDA-approved.
Estradiol vs estriol at a glance
| Decision point | Estradiol (E2) | Estriol (E3) |
|---|---|---|
| FDA-approved human drugs in the U.S. | Yes—multiple systemic and vaginal dosage forms | None |
| Best-established menopause lane | Systemic vasomotor treatment, bone-loss prevention, and vaginal treatment | The clearest direct evidence is for specific ultra-low-dose vaginal products |
| U.S. route to treatment | Prescription filled through a retail, mail-order, or direct pharmacy, depending on the product | Patient-specific compounding when the legal conditions are met |
| Receptor potency | Reference estrogen in comparative assays | Lower than estradiol; one in-vitro dataset reported 11.3% at ER-alpha and 17.6% at ER-beta |
| Dose conversion | Product-specific dosing only | No validated E3-to-E2 conversion table |
| Insurance | Coverage depends on the exact drug, plan, and pharmacy benefit | Frequently cash-pay; reimbursement must be confirmed with the plan |
| What matters before you pay | Exact product, route, dose, label, and pharmacy | Exact E3 and E2 milligrams, base, route, pharmacy, and whether the final product is compounded |
That is the short answer. Here is the part almost nobody tells you: “stronger” and “weaker” are the two least useful words in this entire conversation when they are detached from route, dose, and product. Women use those words to ask four different questions—will it work, is it safer, how much do I use, and can I get it—and one potency number cannot answer all four.
The FDA gives us one unusually clean visual clue. On its March 21, 2025 list of bulk drug substances nominated for section 503B compounding, estradiol, estradiol cypionate, and estrone carry the mark used for components of FDA-approved drugs. Estriol does not. That document does not decide whether a patient-specific prescription may be compounded under section 503A, but it exposes the approval-status difference in four consecutive lines. We show the document correctly below.
Why doesn't the molecule alone choose the right provider?
The molecule does not choose the provider by itself. Your symptoms, age, uterus status, preferred route, risk history, insurance, state, and whether you want an FDA-approved or compounded product can all change the right care model.
The right online HRT provider isn't the same for every woman — it depends on your symptoms, your age and whether you have a uterus, your medication route preference (patch, pill, gel, or vaginal estrogen), your risk history, your insurance or cash-pay situation, and your state. Some situations belong with an in-person clinician first. Because a general answer can't resolve those for you, use The HRT Index's Find My HRT Path tool to match your situation to the right provider — and to flag when online care isn't the right starting point — before your first consult.
The HRT Index is the independent decision resource for online menopause and HRT care — comparing telehealth providers on clinical legitimacy, care quality, medication fit, price transparency, and access, with every claim verified and dated, so women can choose the path that fits their situation before their first consult.
Estradiol vs estriol: what is the difference?
Estradiol is the principal estrogen during the reproductive years and the molecule used in many FDA-approved menopause products. Estriol rises dramatically during pregnancy and has lower estrogen-receptor activity in comparative laboratory assays. For a prescription decision, however, regulatory status, route, dose, and the finished product matter more than the hormone nickname.
Your body makes three major endogenous estrogens:
- Estradiol (E2) is the dominant circulating estrogen during most of the reproductive years.
- Estriol (E3) is produced in large amounts during pregnancy and circulates at much lower levels outside pregnancy.
- Estrone (E1) becomes a more prominent circulating estrogen after menopause.
A manufactured hormone can be described as bioidentical when its molecular structure matches the hormone the body makes. That word is where the marketing gets slippery.
Bioidentical is a chemistry description, not an approval level. FDA-approved estradiol patches, gels, tablets, and other products can be bioidentical. A patient-specific compounded product can also contain bioidentical hormones. The word alone tells you nothing about whether the finished product went through FDA review, whether product-specific absorption was measured, or whether the dispensed strength matches an approved label. See how the HRT categories fit together.
For a real-world comparison, use this order:
- Regulatory status: Was the finished product reviewed and approved, or was it compounded for an individual prescription?
- Route and treatment target: Is it intended to act systemically or mainly in vaginal tissue?
- Dose and regimen: How many milligrams or micrograms are delivered per dose, by what device, and how often?
- Formulation: What base, patch system, insert, ring, tablet, or gel actually controls delivery?
- Potency: What did the molecule do in a particular laboratory assay?
Most pages start at number five and stop. That is how “estriol is gentler” turns into a dosing theory it cannot support.
Is estriol FDA-approved in the United States?
No. FDA states that there are no FDA-approved drugs containing estriol for human use in the United States. Patient-specific estriol may be compounded when the applicable legal conditions are met, but that pathway does not turn the finished preparation into an FDA-approved drug.
The FDA document that shows the difference—and what it does not prove
FDA's March 21, 2025 document, Bulk Drug Substances Nominated for Use in Compounding Under Section 503B, explains that a double asterisk marks a bulk substance that is a component of an FDA-approved drug. The four estrogen entries appear together:
| FDA 503B Category 1 entry | Marked as a component of an FDA-approved drug? |
|---|---|
| Estradiol | Yes—double asterisk |
| Estradiol cypionate | Yes—double asterisk |
| Estriol | No mark |
| Estrone | Yes—double asterisk |
That is a useful regulatory-status check. It is not the whole compounding law.
Section 503A and section 503B are different pathways. FDA explains that a bulk substance used under section 503A must satisfy one of several statutory routes, including compliance with an applicable USP or NF monograph when one exists. USP publishes an official Estriol drug-substance monograph; it also publishes an Estriol Compounded Vaginal Cream monograph at 0.5 mg/g (0.05%). A licensed prescriber and pharmacy still have to satisfy the other applicable patient-specific compounding requirements.
So the accurate version is:
- Estriol is not an FDA-approved human drug.
- An applicable USP monograph can support use of the bulk substance in section 503A compounding when all other conditions are met.
- A USP monograph is not FDA approval of a finished drug.
- Appearance on FDA's 503B Category 1 list is an interim evaluation and enforcement-policy fact for outsourcing facilities, not a blanket approval or the legal basis for every patient-specific prescription.
Three things that still do not follow from “not FDA-approved”:
- It does not mean the estriol molecule is fictional.
- It does not mean every lawfully operating compounding pharmacy is doing something wrong.
- It does not prove that estriol is dangerous.
It means FDA has not reviewed and approved a finished human estriol drug for safety, effectiveness, manufacturing consistency, and labeling in the United States. FDA also says it does not have evidence that drugs containing estriol are safer or more effective than FDA-approved hormone therapy.
Where estriol is approved
Estriol does have authorized human medicines in other countries. For example, Ireland's Health Products Regulatory Authority lists Blissel 50 micrograms/g vaginal gel as an authorized medicine containing estriol, although its current database status says it is not marketed in Ireland. Current U.K. product information also exists for estriol 1 mg/g vaginal cream. Those are defined products with country-specific labels and regulatory oversight—not evidence that a different U.S. compounded cream is equivalent.
| Market and product | Estriol strength | Regulatory fact |
|---|---|---|
| United States, human use | — | No FDA-approved human estriol drug |
| Ireland, Blissel vaginal gel | 50 micrograms/g (0.005%) | Authorized by HPRA; current record says not marketed in Ireland |
| United Kingdom, estriol vaginal cream | 1 mg/g (0.1%) | Current licensed product information |
| United States, Incurin animal drug | 1 mg tablets | FDA-approved for urinary incontinence in spayed female dogs; label says “Not for human use” |
Read that last row precisely. The estriol approval people sometimes find in the U.S. database is an animal-drug approval, not a human-drug approval. It provides no human indication, human dosing precedent, or permission to use the veterinary product.
And the fair half belongs in the same breath: “not FDA-approved” is a fact about U.S. human-drug regulation. It is not a verdict that every approved estriol product in another country is junk science. The honest comparison is product against product, route against route, and regulator against regulator—not slogan against slogan.
Primary sources: FDA on menopause and estriol · FDA 503B Category 1 document · FDA section 503A bulk-substance requirements · USP Estriol drug-substance monograph · USP estriol compounded vaginal cream monograph · HPRA Blissel record · FDA Incurin review
Which is stronger, estradiol or estriol?
Estradiol is more potent than estriol in comparative estrogen-receptor assays. One in-vitro dataset summarized by NCATS reported estriol binding at 11.3% of estradiol's reference affinity at ER-alpha and 17.6% at ER-beta. Those figures describe one laboratory comparison—not a safety score, clinical-effectiveness ratio, or prescription conversion.
The memorable part is real: estriol generally has lower estrogenic potency than estradiol. The mistake begins when a receptor number is asked to do work it was never designed to do.
Potency is not safety. A lower-potency estrogen used orally at a higher dose for years is not automatically safer than a stronger estrogen used at a low vaginal dose. The endometrium does not grade hormones by marketing adjective.
Potency is not a dose conversion. A value from an in-vitro binding assay does not tell you how much hormone leaves a cream base, crosses a tissue barrier, circulates, or reaches a treatment target.
Potency is not clinical effectiveness for a symptom. Hot flashes require sufficient systemic exposure. Vaginal dryness may respond to a low local dose. A molecule can be less potent at a receptor and still work in a particular finished product at a particular regimen.
Potency is not proof of tissue selectivity. Estriol's higher relative number at ER-beta than ER-alpha in that one comparison is not enough to claim that an estriol product “targets only the vagina,” avoids breast or uterine tissue, or has no systemic effect.
Different assays, tissues, endpoints, and dosing conditions produce different relative-potency estimates. Publishing “one-tenth,” “one-eightieth,” or “one-hundredth” without the assay attached invites the exact conversion mistake this page is trying to stop.
The safe sentence is also the useful one: estradiol is more potent; the size of that difference cannot be used to calculate your prescription.
Source: NCATS Inxight Drugs—estriol
What concentrations and strengths do estradiol and estriol products use?
The label has to be read in units, not hormone nicknames. Verified products and monographs span creams measured in milligrams per gram, inserts measured in micrograms per dose, rings measured by daily release, and gels measured by concentration plus a product-specific dose. “Estriol cream” and “estradiol cream” are incomplete descriptions until strength, amount, route, and frequency are known.
This is not “every concentration ever published.” It is a set of seven verified reference strengths, each labeled by product status and unit, so unlike numbers are not presented as though they mean the same thing.
| Reference product or standard | Hormone | Published strength or delivery | Status | What the number means |
|---|---|---|---|---|
| Blissel vaginal gel | Estriol | 0.005% = 0.05 mg/g | Authorized in Ireland | Concentration per gram of gel |
| Estradiol vaginal cream | Estradiol | 0.01% = 0.1 mg/g | FDA-approved finished products exist | Concentration per gram of cream |
| USP estriol compounded vaginal cream monograph | Estriol | 0.05% = 0.5 mg/g | Compounding monograph, not product approval | Target labeled concentration for the monograph preparation |
| U.K. estriol vaginal cream | Estriol | 0.1% = 1 mg/g | Licensed U.K. product | Concentration per gram of cream |
| Estradiol vaginal insert | Estradiol | 10 micrograms per insert | FDA-approved finished products exist | Fixed amount in one insert |
| Estring vaginal system | Estradiol | 2 mg reservoir; about 7.5 micrograms/day for 90 days | FDA-approved | Release rate, not one applied dose |
| Estradiol gel 0.1% | Estradiol | 1 mg/g, dispensed in product-specific unit doses | FDA-approved finished products exist | Concentration plus a formulation-specific dose unit |
Two rules from that table will save you more confusion than any “E2 versus E3” chart.
1. Percentage is concentration, not the dose you use
For a cream, the arithmetic for the amount contained in what is applied is:
milligrams per gram × grams per application × applications per week = dispensed milligrams per week
That still is not the amount absorbed into the bloodstream. It is simply the hormone contained in the applied cream.
Take estradiol vaginal cream at 0.01%, which equals 0.1 mg/g:
- 1 gram twice weekly contains 0.2 mg per week.
- 2 grams daily contains 1.4 mg per week.
Those arithmetic examples are sevenfold apart in the amount contained in the applied cream, despite using the same concentration. They are not suggested regimens and do not tell you what your dose should be.
2. Similar-looking percentages do not make two prescriptions equivalent
Estriol 0.1% and estradiol 0.01% differ tenfold in labeled milligrams per gram, but they are also different molecules, often different bases, and may be used under different regimens for different treatment targets. You cannot cancel one zero against another and call the answer a conversion.
3. A delivery-rate product cannot be compared to a cream by lining up one number
A ring that releases micrograms per day, a patch labeled in micrograms per day, a cream labeled in milligrams per gram, and an insert labeled per dose are different delivery systems. The label gives you the coordinates. It does not give you permission to flatten the map.
Product sources: Blissel authorization · Estradiol vaginal cream label · Estradiol vaginal insert label · USP estriol drug-substance monograph · USP estriol compounded-cream monograph · U.K. estriol cream information · Estring label · Estradiol gel label
Can you convert an estriol dose into an estradiol dose?
No validated conversion table turns an estriol dose into an estradiol dose across products or routes. Receptor-affinity ratios are laboratory measurements, while a prescription depends on formulation, release, absorption, route, treatment target, and regimen. Do not use potency arithmetic to replace one prescription with the other.
Here is the reasoning trap:
“Estradiol is many times stronger than estriol.”
→ “So I can divide the estriol milligrams by that number.”
→ “Now I know the estradiol dose that replaces it.”
The first sentence can be directionally true. The rest does not follow.
- Receptor activity is not exposure. The amount that reaches tissue depends on how the finished product releases the hormone and where it is used.
- The units are not interchangeable. Milligrams per gram, milligrams per pump, micrograms per day, one insert, and one tablet describe different things.
- The target is not interchangeable. A systemic dose intended to reduce hot flashes is not the same treatment problem as a low vaginal dose intended to rebuild local tissue.
- The formulation matters. FDA-approved products have product-specific data and labeling. A compounded preparation is not required to carry FDA-reviewed pharmacokinetic data for that exact patient-specific formula and base.
- The regimen matters. A loading schedule, maintenance schedule, cyclic schedule, and continuous schedule cannot be compared by concentration alone.
The eight-field label decoder
Do not ask “What is the percentage?” and stop. Write down all eight fields:
| Field | What to capture | Why it matters |
|---|---|---|
| 1. Hormone | E2, E3, or both | Identifies what is actually dispensed |
| 2. Exact concentration | mg/g, mg/mL, or another printed unit | Gives the amount per unit of product |
| 3. Amount per dose | Grams, pumps, inserts, tablets, or patch delivery rate | Turns concentration into a real dose unit |
| 4. Frequency | Daily, twice weekly, cyclic, or another schedule | Turns one dose into a regimen |
| 5. Route | Oral, transdermal, or vaginal | Changes exposure and treatment target |
| 6. Intended target | Systemic symptoms, vaginal symptoms, or both | Stops symptom mismatches |
| 7. Product status | FDA-approved finished product or compounded preparation | Tells you what regulatory review applies |
| 8. Dispensing pharmacy and base | Retail/manufacturer product or named compounding pharmacy and cream base | Matters for product identity and absorption assumptions |
That table is deliberately more demanding than “E3 is weaker.” It also gives your prescriber or dispensing pharmacist something they can actually work with.
If your label omits the concentration of each hormone, ask for it in milligrams per gram or milligrams per pump before using potency language at all. If you are switching products, the prescriber should specify the new product and regimen; the patient should not reverse-engineer it from a receptor ratio.
→ Still unsure whether your prescription is systemic or local, FDA-approved or compounded, and which care model fits it? Use Find My HRT Path to sort those decisions before your consult. It does not calculate or change a dose.
Is estriol safer than estradiol?
No evidence supports treating estriol as the “safe estrogen.” A large Swedish case-control study found higher endometrial-cancer risk with long-term oral estriol, while its vaginal findings were smaller and potentially confounded. The comparison does not make vaginal estradiol risk-free; it shows why route, dose, duration, endometrial protection, formulation, and personal history matter more than a gentler-sounding molecule name.
This is the section that changes the answer, so the study design and limits belong beside the headline number.
| Evidence | Route and exposure | What it found | What it can—and cannot—tell you |
|---|---|---|---|
| Weiderpass et al., Lancet 1999; 789 endometrial-cancer cases and 3,368 controls | Oral estriol, typically 1–2 mg/day | Ever-use was associated with about twice the risk; five or more years was associated with an odds ratio of 3.0; atypical endometrial hyperplasia with an odds ratio of 8.3 | Observational evidence, not a randomized trial; it directly contradicts the claim that lower potency guarantees endometrial safety |
| Same Swedish study | Vaginal low-potency estrogen formulations | A weaker association was reported; the authors said concurrent oral-estrogen use might explain it | It does not support saying vaginal estriol had “no association” or zero risk |
| 2019 systematic evidence review of low-dose vaginal estrogens | Low-dose vaginal estrogen products in menopausal women | Did not find an increased endometrial-hyperplasia or cancer signal within the available studies | The review excluded estriol studies, and it called for longer-term real-world data |
Endometrial hyperplasia means overgrowth of the uterine lining. Some forms can progress to cancer, which is why it matters even when a person has no symptoms.
The study is old. It is also one of the clearest direct answers to a claim that is still being sold today. A lower-potency hormone used by mouth for years did not acquire a safety halo because it was estriol.
The wrong lesson would be “vaginal estradiol is automatically safe.” The useful lesson is more specific:
- Route matters. Oral, transdermal, and vaginal treatment do not create the same exposure pattern.
- Dose and duration matter. A loading phase, maintenance phase, and years of systemic exposure are not interchangeable.
- The uterus matters. If you have a uterus and use systemic estrogen, a plan for endometrial protection—usually adequate progestogen—has to be addressed.
- The finished product matters. A licensed or FDA-approved product's evidence cannot simply be pasted onto a different compounded base and concentration.
- Your history matters. Unexplained bleeding, prior estrogen-dependent cancer, clotting history, and other clinical factors change the decision.
Our editorial position, stated as ours: “estriol is the safe estrogen” is one of the most harmful sentences in this category because it moves attention away from route, dose, duration, formulation, endometrial protection, and personal risk—and parks it on a molecule nickname.
You will also see claims that estriol protects against breast cancer or avoids breast effects. Those claims are not established in humans. ACOG and the National Academies both reject using marketing claims about compounded “bioidentical” hormone therapy as a substitute for evidence from approved products and properly studied formulations.
If you have a uterus and are considering systemic estrogen—estradiol, estriol, or a blend—the endometrial-protection question belongs in the prescription plan. See when progesterone is and is not usually part of a vaginal-estrogen decision.
Sources: Weiderpass et al., 1999 · Systematic review of low-dose vaginal estrogen and endometrial safety · ACOG on compounded menopausal hormone therapy · National Academies review
Which is better for hot flashes, night sweats, and sleep disruption?
For hot flashes and night sweats—and sleep disruption driven by them—systemic hormone therapy is the relevant lane. In a U.S. estradiol-versus-estriol decision, FDA-approved systemic estradiol products have the clear advantage: approved indications, printed strengths, product-specific labels, and multiple routes. No FDA-approved systemic estriol drug exists for humans in the United States.
Hot flashes and night sweats are not a local vaginal-tissue problem. The treatment has to provide sufficient systemic exposure to affect thermoregulation. FDA-approved estradiol options include oral, transdermal, and other product-specific routes, each with its own label and dose range.
The Menopause Society states that hormone therapy is the most effective treatment for vasomotor symptoms and helps prevent bone loss and fracture. It does not say that one route, dose, or product is right for every woman. Age, time since menopause, uterus status, symptom burden, health history, and personal preference all matter.
The question to ask when compounded estriol or Bi-Est is offered for hot flashes
Ask this before debating potency:
What problem does this compounded formulation solve for me that an FDA-approved systemic estradiol product does not?
There can be a legitimate answer. A documented allergy to an inactive ingredient, an unavailable dose or dosage form, or another clinically significant need may justify compounding. “It is gentler” is not a product-specific answer, and “bioidentical” does not distinguish a compounded blend from FDA-approved estradiol.
If you still have a uterus
Systemic estrogen can stimulate the endometrium. The plan must address endometrial protection; for most estradiol regimens that means an appropriate progestogen strategy. A Bi-Est ratio does not replace that conversation, and using estriol does not erase it.
Where the provider decision changes
Midi Health's public pricing page currently lists $250 for an initial self-pay visit and $150 for a follow-up, with no membership required. It is in network with many PPO plans. Midi says it is not enrolled with Medicare or Medicaid; people with Medicare may self-pay but cannot submit Midi-related claims to Medicare, while Medicaid and Medi-Cal members cannot be treated through Midi.
→ Want to check whether an insurance-billed menopause specialist model fits your state and plan? See Midi Health's current pricing and insurance page.
The HRT Index has an affiliate relationship with Midi Health. The pricing and insurance facts above were verified from Midi's public page on September 1, 2026. Affiliate disclosure.
Sources: The Menopause Society 2022 hormone-therapy position statement · FDA menopause information · Midi pricing and insurance
Which is better for vaginal dryness, painful sex, and recurrent UTIs?
For genitourinary syndrome of menopause, both molecules have direct vaginal evidence—but the U.S. access answer is different. FDA-approved low-dose estradiol vaginal products have defined labels and strengths. Estriol has licensed vaginal products in some countries, but no FDA-approved U.S. human product; an American estriol prescription is compounded.
Genitourinary syndrome of menopause, or GSM, can include vaginal dryness, burning, irritation, painful sex, urinary urgency, and recurrent urinary tract infections. Here, the treatment target is local tissue rather than hot-flash control, so a low vaginal dose can be enough even when systemic therapy is unnecessary.
What FDA-approved estradiol choices exist in the U.S.?
Estradiol options include:
- Vaginal cream at a labeled concentration such as 0.01% (0.1 mg/g).
- Vaginal tablets or inserts, including fixed microgram doses.
- A vaginal estradiol ring designed to release a low daily amount over 90 days.
That is not the entire U.S. GSM formulary. Conjugated-estrogen vaginal cream, vaginal prasterone, and oral ospemifene are also FDA-approved options for specific indications. They are not estradiol-versus-estriol products, but leaving them out would make a reader search again.
Is vaginal estriol evidence-free?
No. Licensed products such as Blissel and estriol 1 mg/g cream have product-specific evidence and country-specific labels. That is a real clinical lane. What does not follow is that a U.S. compounded cream at another concentration, in another base, has the same absorption or evidence.
Does “local” mean zero systemic exposure?
No. Product information for both estradiol and estriol vaginal products documents systemic absorption. The exposure is generally lower with low-dose vaginal treatment than with systemic treatment, but lower is not zero. Any provider claiming that a vaginal estrogen has no systemic effect is making an absolute claim the labels do not support.
What about recurrent UTIs?
The current AUA/CUA/SUFU guideline recommends vaginal estrogen for peri- and postmenopausal women with recurrent urinary tract infections when there is no contraindication. That recommendation is about vaginal estrogen as a treatment category, not proof that a compounded estriol product is superior to FDA-approved estradiol.
What does access cost?
Medication cost depends on the exact product, pharmacy, location, insurance benefit, and current discount terms. A national “starting at” figure without a ZIP code, named pharmacy, and dated checkout cannot serve as a universal U.S. price.
Sesame's current menopause program advertises care from $59 per month. Its page says the subscription includes ongoing clinician access and basic lab testing when medically necessary, subject to state limitations. Prescriptions can be sent to a local pharmacy; medication cost is separate. The current terms say to cancel at least 48 hours before the next renewal to avoid another charge, and they limit first-month refunds once the initial visit has occurred.
→ Prefer a cash-pay subscription that can send an FDA-approved prescription to a local pharmacy? See Sesame's current menopause-program terms and state availability.
The HRT Index has an affiliate relationship with Sesame. The price, lab, pharmacy, and cancellation statements above were verified from Sesame's public menopause page on September 1, 2026. Affiliate disclosure.
For application details, leakage, timing, cleaning, and what the product label actually says, read our vaginal-estrogen guide.
Sources: The Menopause Society hormone-therapy statement · AUA recurrent UTI guideline · Estradiol vaginal cream label · U.K. estriol cream product information · Sesame menopause program
Does estriol change the answer if you take tamoxifen or an aromatase inhibitor?
It changes the evidence you can discuss, not who should make the decision. A small randomized trial tested one ultra-low-dose 0.005% estriol vaginal gel in 61 breast-cancer survivors taking nonsteroidal aromatase inhibitors. It did not establish that a different compounded U.S. estriol cream is safe, equivalent, or appropriate for every survivor.
This section has no provider link on purpose. The decision belongs with the patient, gynecologist, and oncology team.
What BLISSAFE actually tested
The 2020 BLISSAFE trial was randomized, double-blind, and placebo-controlled. It enrolled 61 postmenopausal women with hormone-receptor-positive early breast cancer who were taking a nonsteroidal aromatase inhibitor. Fifty received the estriol gel and 11 received placebo for 12 weeks.
The study tested a specific 0.005% estriol vaginal gel—50 micrograms of estriol per gram—not “estriol” as a universal category. Vaginal symptoms improved. FSH and LH remained in postmenopausal ranges, and estradiol and estrone were below the assay limit in nearly all samples. Estriol rose early and then declined during treatment.
The conflict and limits most summaries omit
- The trial was small and lasted 12 weeks.
- The sponsor was ITF Research Pharma/Italfarmaco, the product's manufacturer.
- Sponsor employees were authors, and funding relationships were disclosed.
- It studied one licensed gel, concentration, dosing schedule, and base.
- It did not test a 0.05%, 0.1%, or custom compounded U.S. cream.
- It was not powered to establish breast-cancer recurrence outcomes.
That does not invalidate the trial. It tells you where the evidence stops.
What ACOG says for tamoxifen and aromatase inhibitors
ACOG recommends trying nonhormonal approaches first. If symptoms persist, low-dose vaginal estrogen may be used after discussion of risks and benefits, including for people taking tamoxifen. For people taking an aromatase inhibitor, ACOG specifically calls for shared decision-making among the patient, gynecologist, and oncologist.
The practical difference matters. Tamoxifen blocks estrogen receptors in breast tissue; aromatase inhibitors suppress estrogen production and aim to keep circulating estrogen extremely low. That is why a search result should not make the choice for you.
Bring the BLISSAFE citation to your oncology team. Ask whether its product, dose, duration, and population are relevant to your situation—and whether a U.S. FDA-approved option, a nonhormonal option, or no local hormone is the better choice. See the full vaginal-estrogen guide.
Sources: BLISSAFE trial · ACOG guidance for people with a history of estrogen-dependent breast cancer
What is Bi-Est, and what does 80/20 mean?
Bi-Est is a compounded blend of estriol and estradiol. The ratio describes the hormones by weight, not by biologic effect. “80/20” is incomplete unless the label names which hormone is first, gives the total concentration, and states the dose amount—because compounding sources write the same estriol-heavy blend in opposite numerical orders.
If a clinic has offered you Bi-Est, this is the section that matters more than the word “natural.”
The ratio is by weight, not by effect
When a formula is 80% estriol and 20% estradiol by weight, it contains four times as many estriol milligrams as estradiol milligrams. That does not mean estriol produces 80% of the clinical activity. Relative receptor potency, absorption from the base, route, tissue exposure, and regimen are not normalized by the ratio.
No clinical trial lets you assign a reliable percentage of a compounded blend's symptom effect to each component. The honest conclusion is narrower: the weight ratio cannot be read as an activity ratio.
The numerical order is not standardized across public pages
We checked the way compounding sources write estriol-heavy Bi-Est formulations:
| Source | Public notation | What it means on that page |
|---|---|---|
| Wells Pharmacy Network | 80/20 | 80% estriol, 20% estradiol |
| Keystone Pharmacy | 20:80 | 20% estradiol, 80% estriol—the same hormone proportions in reverse order |
| Empower Pharmacy | Offers 50:50 and 80:20 Bi-Est strengths | The hormone order must be confirmed from the full product description or prescription |
| Park Compounding | 2.5 mg Bi-Est example | 2 mg estriol + 0.5 mg estradiol |
That is the original evidence block most pages are missing. “Bi-Est 80/20” is not enough information by itself. The prescription needs to name the hormones in order and show the actual milligrams.
The arithmetic that helps—and the line it cannot cross
For a formula explicitly defined as 80% estriol and 20% estradiol:
- A total of 1.25 mg/g contains 1 mg estriol and 0.25 mg estradiol per gram.
- A total of 2.5 mg contains 2 mg estriol and 0.5 mg estradiol in that stated dose.
That tells you what is in the formula. It does not tell you how much reaches the bloodstream, whether the dose is appropriate, or what approved estradiol product it “equals.” Similar nominal milligram numbers on an approved gel and a compounded cream are not interchangeable because the delivery systems and product-specific data are different.
What should appear on a usable Bi-Est label or prescription?
At minimum:
- Estriol concentration in mg/g or mg per measured dose.
- Estradiol concentration in mg/g or mg per measured dose.
- Total amount applied per dose.
- Route and application site.
- Frequency.
- Cream base or dosage form.
- Dispensing pharmacy.
- Endometrial-protection plan if systemic exposure is intended and the patient has a uterus.
If the product page gives you only “80/20,” you do not yet have enough information to compare it.
Sources: Wells Pharmacy Network Bi-Est explanation · Keystone Pharmacy Bi-Est notation · Empower Pharmacy Bi-Est product information · Park Compounding Bi-Est explanation
Why can an estradiol blood level look low when you take Bi-Est?
A standard estradiol test is designed to measure estradiol, not total estrogen from a compounded blend. Estriol shows very low, assay-specific cross-reactivity on common estradiol immunoassays, so an E2 result does not measure most of the E3 in Bi-Est. That still does not make the number a reliable dosing target for compounded therapy.
This is where a plausible lab number gets turned into a story it cannot tell.
Most routine estradiol tests use antibodies that recognize estradiol. Chemically similar steroids can sometimes trigger a small signal, called cross-reactivity. Published data for a commonly used Roche estradiol immunoassay found very low estriol cross-reactivity—well below 1% in the tested conditions.
That creates three hard limits:
| Question | What the estradiol result can show | What it cannot show |
|---|---|---|
| Is estradiol present in my blood? | It can estimate circulating estradiol within the assay's measuring range | It does not directly measure most circulating estriol |
| Is my Bi-Est dose “high enough”? | The result may contribute to a clinician's broader assessment in selected situations | It cannot validate the total potency, absorption, or clinical effect of a compounded E2/E3 blend |
| Can the result convert my blend to an approved product? | No | It cannot create a product-to-product dose conversion |
| Does a low result prove the cream failed? | No | Symptoms, adherence, timing, formulation, route, and assay limits all sit between the prescription and the number |
Do not turn that into “the test is useless.” It is a test for estradiol. The problem is asking it to report “total estrogen exposure” from a product containing a different estrogen.
ACOG states that evidence for using adjunctive hormone tests to prescribe and dose compounded bioidentical menopausal hormone therapy is limited and does not recommend those tests for that purpose. FDA-approved estradiol gel labeling also says serum FSH and estradiol levels are not useful for managing moderate-to-severe vasomotor symptoms.
The takeaway is the opposite of “go chase a higher number.” If someone presents one estradiol result as proof that a compounded blend is working, failing, or safely dosed, ask what the assay measured, what it did not measure, and what clinical decision the number is supposed to change.
Sources: Cross-reactivity of steroid hormone immunoassays · ACOG on compounded hormone testing · Estradiol gel prescribing information
What about estriol face cream?
Estriol face cream is a separate product category, not a menopause-treatment substitute and not evidence that a vaginal or systemic product is appropriate for facial skin. Concentration alone cannot bridge the gap between tissues, bases, dosing instructions, and tested uses. Do not repurpose a vaginal prescription onto your face without the prescriber's direction.
Two rules keep this clean:
- “Same hormone” does not mean same finished product. A vaginal cream, facial cream, transdermal systemic cream, and gel can use different bases and be intended for different tissues and exposure patterns.
- Cosmetic claims and menopause-treatment claims are different questions. A seller's before-and-after language does not establish systemic symptom control, vaginal benefit, or safety.
The published facial-estrogen evidence is limited, uses varied formulations, and does not establish that the current compounded products sold online are equivalent to one another. The seller, concentration, pricing, and study evidence belong in a separate investigation so they do not contaminate this decision. Read the prescription estriol face-cream investigation.
Where can you get estradiol or estriol in the U.S., and what does it cost?
Estradiol can be prescribed as an FDA-approved finished product through insurance-billed or cash-pay care models. Estriol is obtained through compounding in the U.S. Provider fees and medication fees are separate variables, and several platforms mix FDA-approved and compounded lanes. The only honest comparison names the lane, the published price, what the price includes, and what remains unknown.
Provider and price data last checked September 1, 2026. These are provider-published facts, not guarantees that a clinician will prescribe a particular product. Medication choice follows a licensed clinician's review.
| Care path | What the provider publicly offers | Product-status lane | Published price and what it includes | Access and policy details | What still needs confirmation |
|---|---|---|---|---|---|
| Midi Health | Clinician-led menopause care; its HRT materials describe FDA-approved hormone options, and other pages also discuss compounded alternatives in selected circumstances | Primarily an FDA-approved prescribing path; confirm the exact product at the visit | $250 initial visit; $150 follow-up when self-pay; no membership | In network with many PPO plans; not enrolled with Medicare or Medicaid; Medicare may self-pay without submitting related claims, while Medicaid/Medi-Cal members cannot be treated | Exact formulary, plan coverage, pharmacy cost, and whether a compounded alternative is being proposed |
| Sesame menopause program | Subscription care, clinician visits and messaging, basic labs when medically necessary subject to state limits, and prescriptions sent to a local pharmacy | The clinician can prescribe FDA-approved products when appropriate; the program is not itself a drug | From $59/month; medication cost is separate | Cancel at least 48 hours before the next renewal to avoid another charge; first-month refund is limited once the initial visit occurs | Your state availability, the booked clinician, medication price, and whether a requested lab is included |
| Winona—estrogen tablets | Winona markets an FDA-approved estradiol tablet option | FDA-approved finished-product lane | From $54/month | Cash-pay platform; ages 35–59; public state list contains 37 states plus Puerto Rico | Exact product/manufacturer, dose, eligibility, shipping, and current checkout total |
| Winona—estrogen patch | Winona markets an FDA-approved estradiol patch option | FDA-approved finished-product lane | From $149/month | Same age and state limits | Exact product/manufacturer, patch strength, and current checkout total |
| Winona—Estrogen Body Cream | A compounded 50/50 estriol/estradiol cream | Compounded; the final product is not FDA-approved | From $89/month | Winona provides a 24-hour review window after an order; after pharmacy processing, cancellation/refund is restricted | Exact mg/g of E3 and E2, container size, and dose count are not published on the product page |
| Winona—Vaginal Estrogen Cream | A compounded vaginal estrogen cream | Compounded; the final product is not FDA-approved | From $89/month | Same platform restrictions | Exact hormone formula, concentration, container size, dose count, pharmacy, and current checkout total |
| Inner Balance—Oestra | A compounded vaginal cream publicly described as estradiol 3 mg (0.3%) plus micronized progesterone 100 mg (10%) | Compounded; not an estriol product and not FDA-approved as a finished drug | Full pricing pages state $199/month for the first six months, then $99.50/month; shipments are described as 90-day supplies | Cash-pay membership model | Eligibility, pharmacy identity for the individual order, full refill/cancellation terms, and whether the combined vaginal formula fits the patient's clinical needs |
| Independent compounding pharmacy | Patient-specific estriol, Bi-Est, or another custom preparation when prescribed | Compounded; final product not FDA-approved | Varies; many pharmacies do not publish a universal price | Prescription and applicable compounding requirements apply | Formula, base, quantity, testing, beyond-use date, shipping, insurance reimbursement, and refill policy |
Why Hers is not in this table: Hers is an affiliate partner, but it does not resolve this E2-versus-E3 access decision, and we are not routing readers to it here. On July 29, 2026, the FTC, California, and Utah filed a pending complaint alleging unlawful health-data sharing and deceptive billing and cancellation practices. Those are allegations, not findings. Hims & Hers disputes them and says it will defend the case.
What the price table does not pretend to know
- An advertised provider fee is not the same as the medication price.
- “From” pricing can depend on product, shipment cadence, or plan length.
- A provider's catalog does not guarantee that a clinician will prescribe your preferred hormone.
- HSA/FSA acceptance does not guarantee reimbursement or tax eligibility.
- An FDA-approved ingredient does not make a compounded finished product FDA-approved.
- Cash prices at retail pharmacies vary by location, plan, pharmacy, and date; a national discount-card number without a ZIP and pharmacy is not a reliable universal starting price.
That separation is why the cheapest-looking line is not always the cheapest path. An insurance-billed consult plus a covered generic can beat a low monthly membership; a predictable subscription can beat an out-of-network specialist; a custom formula can cost more but solve a legitimate formulation problem. The right comparison is the first 90-day total for your lane, not one number stripped of its conditions.
Provider sources: Midi pricing and insurance · Sesame menopause program · Winona Estrogen Body Cream · Winona states served · Inner Balance Oestra
What is the honest problem with the compounded route—including with a company that pays us?
Winona sells a 50/50 estriol/estradiol body cream but does not publish the exact E3 and E2 milligrams per gram, container size, or dose count on the public product page. If you need the strength before you pay, that is a real dealbreaker. The same platform also offers FDA-approved estradiol tablets and patches, so the limitation belongs to the compounded product—not every Winona option.
Here is the part an affiliate page is tempted to write around.
Winona's body-cream page gives the ratio and the monthly “from” price. It does not give the concentration needed to calculate the amount of either hormone in one gram or one pump. On a page whose central argument is that you cannot evaluate a hormone cream without its units, that omission matters.
There is a second problem. Winona's public page says the active ingredients estradiol and estriol are FDA-approved. Estradiol is a component of FDA-approved human drugs. Estriol is not. And even when every ingredient is a component of an approved drug, the compounded finished product does not become FDA-approved.
That does not make Winona's cream automatically inappropriate. It means a reader has to get the missing information before treating “50/50” as a usable specification.
Who should choose a different path?
- Choose an FDA-approved product path if product-level FDA review is your priority.
- Choose a provider or pharmacy that publishes the exact formula if you need mg/g and quantity before paying.
- Choose a clinician who can bill your plan if insurance coverage is the deciding constraint.
- Skip Winona if you are outside its 35–59 age range or outside its current service area.
Why Winona is still in the comparison
Winona does not sell only compounded cream. Its public catalog also includes FDA-approved estradiol tablets and patches. That gives a qualified reader an approved-product lane and a compounded lane inside one platform—but the reader still has to confirm the exact product, dose, and total at intake.
→ If the async cash-pay model still fits, check the current age and state eligibility—then ask for the E3 and E2 mg/g in writing before the compounded body cream is dispensed. See Winona's current body-cream page.
The HRT Index has an affiliate relationship with Winona. That relationship is why this limitation is stated here instead of buried. Affiliate disclosure.
When does a compounded hormone genuinely make sense?
Compounding can be a legitimate clinical solution when a patient has a documented need an available FDA-approved product cannot meet—for example, an allergy to an excipient or a medically necessary dose or dosage form that is not available. It should solve a defined patient problem, not merely rebrand an approved option as “natural,” “gentler,” or personalized.
The National Academies' FDA-commissioned review did not say compounded menopausal hormone therapy should never be used. It said use should be restricted to clinical circumstances in which an approved product cannot meet the patient's documented need.
Real examples can include:
- A documented allergy to an inactive ingredient in available approved products.
- A required dosage form that is not commercially available.
- A clinically significant dose need that available products cannot provide.
- A temporary shortage or supply problem handled within applicable compounding rules.
- A patient-specific need the prescriber documents rather than a marketing preference the clinic assigns to everyone.
The question to bring to the prescriber is simple and not hostile:
What specific problem does the compounded version solve for me that an available FDA-approved product does not?
A good answer exists sometimes. If the answer is only “bioidentical,” “custom,” “gentler,” or “safer,” you still do not have the product-level reason.
Seven questions to ask before paying for a compounded estrogen
- What is the exact concentration of each hormone, in mg/g, mg/mL, or mg per measured dose?
- How much product is in the container, and how many prescribed doses does that represent?
- Why is this formulation being used instead of an available FDA-approved product?
- Which pharmacy will compound it, and is the prescription being filled under section 503A or supplied through a registered 503B outsourcing facility?
- What base, storage instructions, and beyond-use date apply to this preparation?
- What potency, identity, sterility, or other quality documentation can the pharmacy provide for this type of preparation and lot?
- What is the full first-fill and refill price, when does billing recur, and what is the cancellation/refund cutoff once the pharmacy begins work?
If a clinic will not answer number one in writing, that is the answer.
Source: National Academies—The Clinical Utility of Compounded Bioidentical Hormone Therapy
Which product claims or impressions fail the primary-source check?
The same failures repeat across this market: calling estriol FDA-approved, turning an approved ingredient into an approved compounded product, claiming zero systemic exposure, and advertising a later maintenance price as though it were the entry price. Those are not wording preferences. They change how a reasonable woman evaluates safety, evidence, and total cost.
The HRT Index checked the public claims below against FDA documents, product information, and the providers' own deeper pricing pages.
| Public claim or impression | Where it appears | What the primary source or fuller page shows | Reader consequence |
|---|---|---|---|
| “The active ingredients estradiol and estriol are FDA approved.” | Winona Estrogen Body Cream page | FDA says no human drug containing estriol is approved in the U.S.; the final 50/50 cream is compounded and not FDA-approved | Do not treat ingredient wording as approval of either estriol or the finished cream |
| “Targeted support without systemic effects.” | Inner Balance facial-estriol education page | The page does not provide product-specific pharmacokinetic evidence proving zero systemic exposure for its compounded facial formula; licensed estriol vaginal information also shows that local application does not inherently mean zero absorption | Treat the absolute as unverified—not as a product fact—especially when exposure matters |
| “All 503A compounding pharmacies … are required to produce prescriptions with FDA-approved ingredients.” | Winona Help Center | Section 503A also recognizes a bulk substance that complies with an applicable USP/NF monograph, plus the statutory bulks-list route, subject to all other requirements | This wording falsely turns a compounding pathway into an ingredient-approval claim |
| Oestra is an estriol option. | Inner Balance Oestra product page and reader assumptions created by grouping it with “bioidentical” compounded products | Inner Balance publishes estradiol 3 mg plus micronized progesterone 100 mg; no estriol | Do not place it in an E3 comparison or cite it as estriol access |
| Oestra starts at $99.50/month. | Inner Balance Oestra pricing | Full pricing pages state $199/month for the first six months, then $99.50/month | The later rate is not the initial six-month rate; compare the first 90 and 180 days |
| Sesame is a pay-per-visit menopause route. | Stale summaries compared with the current Sesame menopause program | The current menopause program is a subscription advertised from $59/month, with its own cancellation and refund rules | A reader choosing it to avoid membership would be choosing from outdated information |
Some of those companies are affiliate partners. That is why the claims are named instead of softened into “some providers.”
So which one is right for you?
The right path depends on the symptom you are treating, whether exposure needs to be systemic or local, uterus status, risk history, country, insurance, and whether a compounded product solves a documented need. The table below is a decision map, not a prescription: it tells you which conversation to have and where a generic online funnel should stop.
| If this is your situation | Path to discuss | Why |
|---|---|---|
| Hot flashes, night sweats, or sleep disruption driven by them | FDA-approved systemic estradiol options | Whole-body symptoms require a systemic-treatment discussion; no FDA-approved systemic estriol drug exists in the U.S. |
| Vaginal dryness or painful sex without systemic symptoms | Low-dose vaginal options, including FDA-approved estradiol products | Local treatment can address GSM without selecting a systemic dose; compounded estriol is not the only route |
| Both vasomotor and vaginal symptoms | Systemic therapy plus a separate GSM assessment | A systemic regimen may not fully resolve vaginal symptoms; adding local treatment can be a distinct decision |
| Recurrent UTIs after menopause | Ask specifically about vaginal estrogen and the current UTI guideline | This use is often missed when the conversation stays focused on hot flashes |
| Taking tamoxifen | Nonhormonal measures first, then a risk-benefit discussion with the oncology-informed care team if symptoms persist | ACOG permits low-dose vaginal estrogen after discussion; tumor and treatment context still matter |
| Taking an aromatase inhibitor | Shared decision among you, your gynecologist, and your oncologist | ACOG specifically calls for oncology involvement; one small estriol-gel trial does not settle every product choice |
| You have a uterus and want systemic estrogen | An explicit endometrial-protection plan | Estriol and Bi-Est do not remove the need to address the uterine lining |
| You live where a licensed estriol product is available | Compare that exact product's label with local estradiol options | “Estriol” is no longer synonymous with “compounded” outside the U.S. |
| You are already using Bi-Est and doing well | Do not reverse-engineer or abruptly change it from this page; bring the eight label fields and seven pharmacy questions to the next review | Symptom response matters, and so do concentration, route, safety plan, and refill terms |
| You have bleeding after menopause or unexplained bleeding | Arrange prompt clinical evaluation before self-starting or changing hormone treatment | Bleeding needs assessment; an article or generic intake should not diagnose the cause |
| You have a history of breast, uterine, or another estrogen-dependent cancer | Specialist-involved decision | The answer depends on cancer type, treatment, recurrence risk, symptom severity, and alternatives |
| You are pregnant, may be pregnant, or are breastfeeding | Contact the clinician managing your care | Menopause-treatment assumptions do not apply |
Still not sure which row fits? Find My HRT Path takes about 90 seconds, requires no email, labels FDA-approved and compounded routes separately, and flags when online care is not the right starting point. It is a routing tool—not a diagnosis or prescription.
What did The HRT Index actually verify for this page?
We checked the approval-status documents, product labels, study methods, sponsor disclosures, provider prices, formulation claims, age and state limits, and cancellation language. Where a public source did not disclose an exact formula or transaction total, the page says so instead of filling the gap with a “starting at” guess.
Read in the original source
- FDA's March 21, 2025 503B Category 1 document, including the double-asterisk legend and the consecutive estradiol, estradiol cypionate, estriol, and estrone entries.
- FDA's section 503A bulk-substance requirements.
- USP's estriol compounded vaginal cream monograph.
- FDA's Incurin animal-drug review and “Not for human use” label language.
- U.S. estradiol product labels and licensed European estriol product information.
- The Weiderpass endometrial-cancer study abstract and the 2019 vaginal-estrogen systematic review, including the fact that the latter excluded estriol studies.
- BLISSAFE methods, results, funding, and author disclosures.
- ACOG's compounded-hormone and breast-cancer-survivor guidance.
- Published Bi-Est ratio conventions from multiple compounding sources.
- Estriol cross-reactivity data for estradiol immunoassays.
- Midi, Sesame, Winona, and Inner Balance public pricing, eligibility, product, and policy pages.
What the public sources still do not establish
- The exact estriol and estradiol mg/g, container size, and dose count for Winona's Estrogen Body Cream before intake.
- Product-specific pharmacokinetics for every U.S. patient-specific compounded estriol or Bi-Est base.
- A validated E3-to-E2 conversion table.
- A universal U.S. retail price for estradiol cream that remains true across ZIP codes, pharmacies, plans, and dates.
- Whether a particular clinician will prescribe the product a reader prefers.
This page was produced under The HRT Index Verification Standard. For the products named here, that meant checking each provider-published price, separating FDA-approved from compounded, verifying state availability and insurance terms, and applying the current re-check schedule—top providers monthly and the full roster quarterly. The five review pillars are clinical legitimacy, care quality, medication fit, price transparency, access. No per-provider numeric score is used on this page.
No patient testimonial is used to prove efficacy or safety. The page does not claim a firsthand treatment experience, a clinician review that did not occur, or a product test that was not performed.
Frequently asked questions
Is estriol FDA-approved?
No human estriol drug is FDA-approved in the United States. Patient-specific estriol may be compounded when applicable legal requirements are met, and licensed estriol products exist in some other countries. The U.S. Incurin approval is for an animal drug used in spayed female dogs, not for human treatment.
Is estriol safer than estradiol?
That has not been established. Long-term oral estriol was associated with higher endometrial-cancer risk in a large observational study, while low-dose vaginal treatment has a different exposure pattern. Safety depends on route, dose, duration, formulation, endometrial protection, and individual history—not the word “estriol.”
Which is stronger, estradiol or estriol?
Estradiol is more potent in comparative receptor assays. One in-vitro dataset reported estriol at 11.3% of estradiol's reference affinity at ER-alpha and 17.6% at ER-beta. Those numbers are not a clinical dose ratio.
How much estradiol equals 1 mg of estriol?
There is no validated answer across products or routes. A receptor-affinity ratio cannot account for the base, release, absorption, route, application site, frequency, or treatment target. A switch requires a new product-specific prescription, not division on a calculator.
Is estriol 0.1% the same as estradiol 0.01%?
No. The first contains 1 mg estriol per gram; the second contains 0.1 mg estradiol per gram. They are different hormones and may be different finished products, bases, doses, and regimens. The percentages do not establish equivalence.
What is Bi-Est 80/20?
It is a compounded E3/E2 blend whose ratio is by weight. Many sources mean 80% estriol and 20% estradiol, but some write the same blend as 20:80 by listing estradiol first. The prescription must name the hormone order and exact milligrams per gram.
Can estriol and estradiol be prescribed together?
Yes. Bi-Est is one compounded combination. Combining them does not make the finished product FDA-approved, establish a dose conversion, or remove the need for an endometrial-protection plan when systemic estrogen is used by someone with a uterus.
Do I need progesterone with estriol?
The molecule name does not answer that. If you have a uterus and use systemic estrogen, the prescription plan generally needs adequate endometrial protection. Low-dose vaginal estrogen is treated differently in guidance, but unexplained bleeding and individual risk still require clinical review.
Is estriol better than estradiol for vaginal dryness?
No evidence establishes compounded estriol as generally better than FDA-approved vaginal estradiol. Specific licensed estriol products have evidence for GSM in other countries. In the U.S., estradiol offers FDA-approved product choices with defined labels; the decision should compare exact products, not hormone nicknames.
Why is my estradiol level low if I use Bi-Est?
A routine estradiol immunoassay measures estradiol and has very low cross-reactivity with estriol. The result does not represent total E2-plus-E3 exposure from the blend. ACOG does not recommend using adjunctive hormone tests to dose compounded menopausal hormone therapy.
Does bioidentical mean FDA-approved?
No. Bioidentical describes molecular structure. FDA-approved estradiol products can be bioidentical, and compounded products can contain bioidentical hormones. Approval applies to a finished product, indication, formulation, manufacturing process, and label—not a marketing adjective.
Is Oestra an estriol product?
No. Inner Balance publicly describes Oestra as compounded vaginal estradiol 3 mg plus micronized progesterone 100 mg. It is a compounded E2/progesterone product, not an E3 product.
Can I use vaginal estradiol or estriol cream on my face?
Do not repurpose a vaginal prescription onto facial skin without the prescriber's direction. The base, dose, application site, tested use, and exposure assumptions differ. Facial estrogen cream is a separate evidence and product category.
Can I buy estriol over the counter in the U.S.?
There is no FDA-approved over-the-counter estriol drug in the United States. A product marketed as containing prescription-strength estriol without a valid prescription and lawful pharmacy process should not be treated as an approved OTC medicine.
Where does this leave you?
Estradiol is the clearer U.S. path when you want an FDA-approved systemic or vaginal product. Estriol has a legitimate, narrower evidence base—especially in specific licensed vaginal products—but U.S. human estriol is compounded. The decision is not “strong versus gentle.” It is product, route, dose, evidence, access, and the problem the prescription is meant to solve.
The argument about which estrogen is “stronger” has been eating the attention that belongs on route, dose, product, and whether anyone has actually reviewed what is in your hand.
Estradiol has FDA-approved human products across multiple systemic and vaginal dosage forms. Those products have defined labels, strengths, indications, and product-specific information. That is why estradiol is the reference point for most U.S. E2-versus-E3 decisions—not because “natural” hormones are good or bad, but because a product you can identify is easier to evaluate than a category word.
Estriol is a real hormone with licensed human products and meaningful evidence in a narrower vaginal-treatment lane. In the U.S., however, it is compounded, and the finished product does not inherit FDA approval from the prescription, the pharmacy, the presence of estradiol beside it, or the word bioidentical.
You're allowed to prefer the compounded version. You're allowed to prefer the approved one. You are also allowed to stop the intake and ask for the units, the pharmacy, the price after the first shipment, and the reason this product solves your problem better.
That is not being difficult. That is making the decision with the numbers in front of you.
Still not sure which HRT program is right for you? Use Find My HRT Path for your free, private match in about 90 seconds.
Sources
Regulatory and product-status sources
- U.S. Food and Drug Administration. Menopause. Includes FDA's statement that no drugs containing estriol are approved for human use in the U.S.
- U.S. Food and Drug Administration. Bulk Drug Substances Nominated for Use in Compounding Under Section 503B. Updated March 21, 2025; rechecked September 1, 2026.
- U.S. Food and Drug Administration. Bulk Drug Substances Used in Compounding Under Section 503A.
- U.S. Pharmacopeia. Estriol drug-substance monograph.
- U.S. Pharmacopeia. Estriol Compounded Vaginal Cream monograph, 0.5 mg/g.
- U.S. Food and Drug Administration, Center for Veterinary Medicine. Incurin freedom-of-information summary, NADA 141-325.
- Health Products Regulatory Authority. Blissel 50 micrograms/g vaginal gel.
- Electronic Medicines Compendium. Estriol 1 mg/g vaginal cream—summary of product characteristics.
- DailyMed. Estradiol vaginal cream 0.01%.
- DailyMed. Estradiol vaginal insert, 10 micrograms.
- DailyMed. Estring estradiol vaginal system.
- DailyMed. Estradiol gel 0.1%.
Clinical guidance and evidence
- The North American Menopause Society. The 2022 hormone therapy position statement.
- American College of Obstetricians and Gynecologists. Compounded Bioidentical Menopausal Hormone Therapy. 2023.
- American College of Obstetricians and Gynecologists. Treatment of Urogenital Symptoms in Individuals With a History of Estrogen-dependent Breast Cancer.
- National Academies of Sciences, Engineering, and Medicine. The Clinical Utility of Compounded Bioidentical Hormone Therapy. 2020.
- Weiderpass E, Baron JA, Adami HO, et al. Low-potency oestrogen and risk of endometrial cancer: a case-control study. Lancet. 1999;353:1824–1828.
- Constantine GD, Graham S, Lapane K, et al. Endometrial safety of low-dose vaginal estrogens in menopausal women: a systematic evidence review. Menopause. 2019.
- Sánchez-Rovira P, Lindén Hirschberg A, Gil-Gil M, et al. Ultra-low-dose 0.005% estriol vaginal gel in women with early breast cancer taking aromatase inhibitors. Menopause. 2020;27(5):526–534.
- Krasowski MD, et al. Cross-reactivity of steroid hormone immunoassays. BMC Clinical Pathology. 2014;14:33.
- National Center for Advancing Translational Sciences. Inxight Drugs—estriol.
- American Urological Association. Recurrent Uncomplicated Urinary Tract Infections in Women guideline.
Provider, price, and policy sources
- Midi Health. Pricing and insurance. Checked September 1, 2026.
- Sesame. Online menopause treatment. Checked September 1, 2026.
- Winona. Estrogen Body Cream, Estrogen Tablet, Estrogen Patch, Vaginal Estrogen Cream, FAQ, and states served. Checked September 1, 2026.
- Inner Balance. Oestra product information and pricing information. Checked September 1, 2026.
- Federal Trade Commission. Pending Hims & Hers complaint, filed July 29, 2026; Hims & Hers response.
- Wells Pharmacy Network, Keystone Pharmacy, Empower Pharmacy, and Park Compounding. Public Bi-Est ratio and formulation pages. Checked September 1, 2026.
Found something wrong or out of date? Tell us. Material corrections are logged and dated.