Last checked September 2026 against 28 sources · Editorial policy
Estrogen replacement therapy
Estrogen replacement therapy replaces the estrogen your ovaries stop making at menopause. It's the most effective treatment for hot flashes, cutting them by about 75%, and it prevents bone loss and treats vaginal dryness. If you have a uterus, you also need a progestogen to protect against uterine cancer; after a hysterectomy, estrogen alone is used. It comes as pills, patches, gels, sprays and vaginal forms.
Estrogen is the most effective treatment for hot flashes and protects bone. Who needs progesterone too, forms and doses, and risks by age.
Estrogen replacement therapy: expectation vs reality
What people often expect
“Estrogen replacement is one risky drug that everyone reacts to the same way”
What the evidence shows
The risks depend on the type, the route and when you start. In large UK databases, estrogen tablets raised clot risk (odds ratio 1.58) but patches and gels didn't (0.93). In the WHI trial, estrogen alone didn't raise breast cancer risk (hazard ratio 0.79). Updated FDA labels now advise considering starting estrogen before 60 or within 10 years of menopause, when the balance is most favorable.
Estrogen replacement therapy explained
What is estrogen replacement therapy?
Estrogen replacement therapy, often shortened to ERT or estrogen therapy, uses estrogen to replace what the ovaries no longer make after menopause. Women who've had a hysterectomy take estrogen alone. Women with a uterus take estrogen with a progestogen, which is called combined HRT or estrogen-progestogen therapy. The goal is to relieve symptoms such as hot flashes, night sweats, poor sleep, low mood and vaginal dryness, and to protect bone.
Learn more →Why estrogen needs a progestogen if you have a uterus
Estrogen on its own makes the lining of the uterus grow, and in women with a uterus this raises the risk of endometrial cancer. Adding a progestogen reduces the risk of endometrial hyperplasia, a possible precursor to cancer. That's why the FDA kept this one boxed warning when it removed others in 2025. The progestogen can be a tablet, part of a combined patch or a 52 mg hormonal IUD.
Learn more →Types of estrogen replacement medications
Most estrogen replacement today is estradiol, the same estrogen the ovaries make. It comes as tablets, patches, gels, a spray and vaginal creams, inserts and rings. Conjugated estrogens, sold as Premarin, are a mix of estrogens from pregnant mares' urine and were used in the WHI trial. Duavee combines conjugated estrogens with bazedoxifene instead of a progestogen, for women with a uterus.
Learn more →Benefits of estrogen replacement therapy
Systemic estrogen reduces hot flash frequency by about 75%, and oral and transdermal estrogen work equally well. It's also the most effective treatment for genitourinary symptoms and has been shown to prevent bone loss and fracture. The NHS adds sleep problems, anxiety and low mood caused by menopause to the list. It isn't used to prevent heart disease: the US Preventive Services Task Force advises against hormone therapy for preventing chronic conditions.
Learn more →Estrogen replacement risks: route, type and timing
Estrogen tablets pass through the liver and raise the risk of blood clots and gallbladder disease; patches and gels don't raise clot risk and carry less gallbladder risk. Among tablets, estradiol had a lower clot risk than conjugated estrogens. Starting under 60 or within 10 years of menopause is favorable; starting later carries higher absolute risks of heart disease, stroke, clots and dementia.
Learn more →Estrogen therapy and breast cancer
Estrogen alone has a smaller effect on breast cancer than combined HRT. In the WHI trial, women taking estrogen alone had fewer breast cancers than those on placebo (104 vs 135). A worldwide analysis of observational studies found a small rise with estrogen alone, relative risk 1.17 in the first 4 years, compared with 1.60 for combined HRT. The NHS says estrogen-only HRT causes little or no increase in risk.
Contraindications to estrogen replacement therapy
FDA labels say estrogen shouldn't be used if you have unexplained genital bleeding, current or past breast cancer, an estrogen-dependent cancer, a current or past blood clot, a past stroke or heart attack, liver disease, or an inherited clotting disorder such as protein C, protein S or antithrombin deficiency. Untreated high blood pressure needs to be controlled first. Low-dose vaginal estrogen follows different rules.
Learn more →Low-dose estrogen: the lowest dose that works
Guidelines advise starting on a low dose, because symptoms often respond to it and higher starting doses cause more side effects. A low dose is about 0.5 mg of oral estradiol, a 25 mcg patch or one pump of estradiol gel. Doses can be raised no sooner than every 3 months if symptoms persist. An even lower 14 mcg a day patch, Menostar, is approved only to prevent bone loss.
Learn more →Natural estrogen replacement: plant estrogens and bioidentical hormones
Plant estrogens don't replace estrogen reliably. In a meta-analysis, red clover isoflavones didn't reduce hot flashes and soy results were mixed, and The North American Menopause Society doesn't recommend soy or herbal remedies. If natural means identical to your own hormone, FDA-approved estradiol already is: it has the same chemical structure as the estradiol your ovaries made. Compounded versions aren't FDA-approved.
Learn more →Estrogen therapy by the numbers
From the studies on this page
reduction in hot flash frequency with systemic estrogen
75%
improvement in vaginal symptoms with low-dose vaginal estrogen
60% to 80%
0.79
0.93
WHI results came from oral conjugated estrogens in women with an average age of 63. Findings in women starting estrogen around menopause, and with estradiol patches or gels, are more favorable.
Types of estrogen replacement compared
Transdermal estrogen: patch, gel or spray
Strong evidenceEstradiol through the skin works as well as tablets for hot flashes and doesn't raise the risk of blood clots. It also carries less risk of gallbladder disease than tablets. It's the usual choice if you're overweight, have had a clot or have other clot risk factors. Patches are changed once or twice a week; gels and sprays are daily.
Related guide →Oral estrogen: estradiol tablets
Strong evidenceDaily estradiol tablets are simple, inexpensive and effective. Many of the benefits of HRT in trials were shown with tablets. The trade-off is a higher risk of blood clots, stroke and gallbladder disease than with transdermal estrogen, which matters most if you have risk factors. Estradiol tablets had a lower clot risk than conjugated estrogen tablets.
Related guide →Vaginal estrogen
Strong evidenceLow-dose estradiol cream, inserts or a ring treat vaginal dryness, painful sex and urinary symptoms directly, improving them by about 60% to 80%. So little reaches the bloodstream that the NHS says it doesn't increase the risk of breast cancer or clots and can be used long term. It doesn't treat hot flashes.
Related guide →Conjugated estrogens (Premarin)
Strong evidenceAn older estrogen made from pregnant mares' urine, available as tablets and a vaginal cream. It treats hot flashes and prevents bone loss, and it's the estrogen studied in the WHI trial. In observational studies, it carried a higher risk of blood clots than oral estradiol, which is one reason estradiol is now more common.
Related guide →Estrogen with bazedoxifene (Duavee)
Some evidenceConjugated estrogens combined with bazedoxifene, a drug that protects the uterine lining, so no progestogen is needed. It's approved for hot flashes and preventing osteoporosis in women with a uterus. In a JAMA review, the low-dose combination wasn't linked with higher breast cancer risk. It isn't recommended for women over 75.
When to talk to a doctor about estrogen therapy
Hot flashes, night sweats or vaginal dryness affecting daily life
Ask about estrogen therapy. Over 45, you usually don't need blood tests to start.
More →Unexpected bleeding while taking estrogen
See a doctor, especially if it starts after several months of treatment. It needs checking to rule out uterine cancer.
More →A breast lump or change in your breasts
See a doctor. Keep up with mammograms while you're on estrogen.
Urgent: Leg pain or swelling, chest pain with breathlessness, or stroke signs
Leg pain, redness or swelling can be a clot: call a doctor now. Chest pain with breathlessness, trouble speaking or a drooping face: call 911.
Estrogen replacement: questions women ask
What is the best estrogen replacement?
For most women, estradiol, the same estrogen your ovaries made. Transdermal estradiol, as a patch, gel or spray, is often preferred because it doesn't raise clot risk. Tablets are simple and cheap. If you have a uterus, you'll need a progestogen too; micronized progesterone and the hormonal IUD are common choices.
What is the safest estrogen replacement?
Low-dose transdermal estradiol has the best safety data for clots: patches and gels weren't linked with blood clots, and low-dose patches didn't raise stroke risk in a large UK study. Low-dose vaginal estrogen is the safest for vaginal symptoms, because so little is absorbed.
Can you take estrogen after menopause?
Yes. Estrogen is approved to treat hot flashes and vaginal symptoms after menopause and to prevent bone loss. Starting before 60, or within 10 years of your last period, gives the most favorable balance. Starting later is possible but the absolute risks of heart disease, stroke and clots are higher.
Do menopausal women need estrogen?
Not all of them. Estrogen is a treatment for symptoms and bone protection, not something every woman must take. It's especially recommended if menopause comes before 45, to protect bones and heart. If symptoms don't bother you, you don't need it.
Why do I need progesterone with estrogen?
If you have a uterus, estrogen alone makes its lining grow and raises the risk of endometrial cancer. A progestogen protects the lining. If you've had a hysterectomy, you usually don't need one, although women with a history of endometriosis sometimes do.
What does low-dose estrogen mean?
Roughly 0.5 mg of oral estradiol, a 25 mcg patch, or one pump of estradiol gel. Guidelines recommend starting low because many women's symptoms respond well, and higher starting doses cause more side effects. The dose can be increased after 3 months if needed.
Related →Is there a natural estrogen replacement for menopause?
Not a reliable one. Red clover didn't reduce hot flashes in a meta-analysis and soy results were mixed; herbal remedies aren't recommended. FDA-approved estradiol is chemically identical to your own estrogen, which is what most people mean by natural.
Related →What are the side effects of estrogen replacement therapy?
The most common are breast tenderness, headaches, nausea, leg cramps, bloating and spotting. They usually settle within a few weeks to 3 months. Serious side effects such as blood clots are rare, and less likely with patches or gels than with tablets.
Related →How long can you stay on estrogen replacement therapy?
There's no fixed limit. Most women take HRT for 2 to 5 years, but some take it longer, reviewing the benefits and risks with their doctor each year. Vaginal estrogen can be used long term.
Related →Does estrogen therapy help with low estrogen symptoms?
Yes. Hot flashes, night sweats, vaginal dryness, poor sleep and low mood caused by menopause are all symptoms of low estrogen, and replacing it is the most effective treatment. Symptoms usually improve within a few weeks, with the full effect by 3 months.
Sources
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- NHS. About hormone replacement therapy (HRT).
- Prescribing information: Divigel (estradiol gel 0.1%). Vertical Pharmaceuticals, 2026. DailyMed, US National Library of Medicine.
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- Manson JE, Chlebowski RT, Stefanick ML, et al. Menopausal hormone therapy and health outcomes during the intervention and extended poststopping phases of the Women's Health Initiative randomized trials. JAMA. 2013;310(13):1353-68.
- NHS. Types of hormone replacement therapy (HRT).
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- Women's Health Concern / British Menopause Society. Fact sheet: HRT types, doses and regimens.
- Prescribing information: Premarin (conjugated estrogens tablets). Wyeth/Pfizer, 2026. DailyMed, US National Library of Medicine.
- Prescribing information: Duavee (conjugated estrogens/bazedoxifene). Wyeth/Pfizer, 2026. DailyMed, US National Library of Medicine.
- NHS. Benefits and risks of hormone replacement therapy (HRT).
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- Prescribing information: Menostar (estradiol transdermal system). Bayer HealthCare, 2026. DailyMed, US National Library of Medicine.
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- The North American Menopause Society. The 2023 nonhormone therapy position statement of The North American Menopause Society. Menopause. 2023;30(6):573-590.
- Stuenkel CA. Compounded bioidentical hormone therapy: new recommendations from the 2020 National Academies of Sciences, Engineering, and Medicine. Menopause. 2021;28(5):576-578.
- Renoux C, Dell'aniello S, Garbe E, et al. Transdermal and oral hormone replacement therapy and the risk of stroke: a nested case-control study. BMJ. 2010;340:c2519.
- Smith NL, Blondon M, Wiggins KL, et al. Lower risk of cardiovascular events in postmenopausal women taking oral estradiol compared with oral conjugated equine estrogens. JAMA Intern Med. 2014;174(1):25-31.
- NICE. Menopause: identification and management (NG23). Updated 2024.
- NHS. Oestrogen tablets, patches, gel and spray: side effects.
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