HRT: What the Evidence Actually Says

Updated August 2026.

In February 2026 the US Food and Drug Administration approved labelling changes that removed statements about cardiovascular disease, breast cancer and probable dementia from the boxed warning on menopausal hormone therapy products. The boxed warning about endometrial cancer for systemic estrogen taken without a progestogen by women who have a uterus remains in place. This is a US regulatory decision; in the UK, product labelling and prescribing guidance sit with the MHRA and NICE and are set separately.

To understand why the conversation about hormone therapy is so confused, you have to understand a single study and what happened to it.

July 2002

The Women's Health Initiative was the largest randomised trial ever conducted on hormone therapy. Two arms: one testing conjugated equine estrogens plus a synthetic progestogen in women with a uterus, one testing estrogen alone in women who'd had a hysterectomy. Tens of thousands of participants.

In 2002 the combined arm was halted early. Press coverage reported increased risks of breast cancer and cardiovascular events. Within a year, prescriptions collapsed across the developed world — in some countries by more than half. A generation of women stopped treatment, and a generation of doctors learned to be wary of starting it.

What was underneath

The findings were real. What was lost was who they applied to.

The average participant was 63 years old. Many were more than a decade past menopause. The trial was designed to test whether hormone therapy prevented chronic disease in older women, not whether it safely relieved symptoms in women in their early fifties. That's a different question with a different risk profile.

It also tested one specific formulation — oral conjugated equine estrogens with medroxyprogesterone acetate. Not the transdermal estradiol and micronised progesterone widely prescribed today.

And the risks were reported as relative rather than absolute. A "26% increase in breast cancer" sounds catastrophic. In absolute terms it corresponded to a small number of additional cases per thousand women per year — a real increase, and a very different thing from what most women understood.

Long-term follow-up published in 2017, covering 18 years, found no significant difference in all-cause mortality between women who had taken hormone therapy and those who hadn't, in either arm.

Where the evidence sits now

The timing hypothesis. The balance of benefit and risk depends substantially on when you start. For most healthy women under 60, or within 10 years of their final period, the risk-benefit profile is favourable for treating bothersome vasomotor symptoms. Starting many years later shifts that calculation, particularly for cardiovascular outcomes.

Effectiveness. Hormone therapy remains the most effective treatment available for hot flushes and night sweats, and for genitourinary symptoms. It also prevents bone loss and reduces fracture risk.

Breast cancer. Combined estrogen-progestogen therapy is associated with a small increased risk that rises with duration of use and declines after stopping. In the WHI estrogen-alone arm, breast cancer incidence was lower than placebo. The absolute numbers matter more than the percentages, and NICE publishes a decision aid giving figures per 1,000 women, with and without HRT, which is the single most useful document to bring to an appointment.

Cardiovascular. Started near menopause in healthy women, hormone therapy does not appear to increase coronary heart disease risk and may reduce it. Started much later, or in women with existing disease, the picture differs.

Clots. Oral estrogen carries a small increased risk of venous thromboembolism. Transdermal estrogen — patch, gel or spray — has not been shown to increase it, because it bypasses first-pass liver metabolism. This is why guidance recommends the transdermal route for women with elevated clot risk, including higher BMI.

Route matters more than most women are told. Oral and transdermal are not interchangeable in terms of risk profile.

What changed in 2025

In November 2025, following an expert panel review and public consultation, the US FDA moved to remove the boxed warnings relating to cardiovascular disease, breast cancer and probable dementia from estrogen-containing menopause products, including vaginal estrogens. The agency's stated reasoning was that the warnings, derived from WHI participants averaging 63 years of age, did not reflect the risk profile of the women who typically start treatment in their late forties and fifties.

The warning about endometrial cancer with systemic estrogen-alone therapy in women who still have a uterus remains — which is precisely why a progestogen is prescribed alongside estrogen in that situation.

The European Menopause and Andropause Society welcomed the decision. It is not a declaration that hormone therapy is risk-free. It's a correction to a warning that had been applied far more broadly than the evidence supported.

What this means for you

It doesn't mean everyone should take it. It means the conversation should be an individual one about your symptoms, your age, your time since menopause, your risk factors and your preferences — rather than a reflex refusal based on a study of women fifteen years older than you.

Contraindications exist and are real: current or past breast cancer in most cases, active liver disease, unexplained vaginal bleeding, a history of hormone-sensitive cancer, and some cardiovascular and clotting conditions. These require a proper discussion, and often a specialist one.

If you're told simply that HRT is dangerous, a reasonable reply is to ask which risk specifically, at what magnitude, and whether that figure comes from a population comparable to you. That's not being difficult. That's the standard of conversation the guidelines themselves ask for.

Sources

- Rossouw JE, Anderson GL, Prentice RL, et al. Risks and benefits of estrogen plus progestin in healthy postmenopausal women: principal results from the Women's Health Initiative randomized controlled trial. JAMA. 2002;288(3):321–333.

Manson JE, Aragaki AK, Rossouw JE, et al. Menopausal hormone therapy and long-term all-cause and cause-specific mortality: the Women's Health Initiative randomized trials. JAMA. 2017;318(10):927–938.

The 2022 hormone therapy position statement of The North American Menopause Society. Menopause. 2022;29(7):767–794.

National Institute for Health and Care Excellence. Menopause: identification and management (NG23), and HRT and the likelihood of some medical conditions: a discussion aid. Updated 2024.

US Food and Drug Administration. HHS advances women's health, removes misleading FDA warnings on hormone replacement therapy. 10 November 2025.

US Food and Drug Administration. FDA approves labeling changes to menopausal hormone therapy products. 12 February 2026.

Makary MA, Nguyen CP, Høeg TB, Tidmarsh GF. Updated labeling for menopausal hormone therapy. JAMA. 2026;335(2):117–118.