What Is Hormone Replacement Therapy?
Hormone replacement therapy (HRT) is a medical treatment that replenishes the estrogen and progesterone your ovaries stop producing during menopause. When a woman reaches menopause — typically between ages 45 and 55 — her estrogen levels drop by as much as 90 percent. That collapse triggers hot flashes, night sweats, vaginal dryness, disrupted sleep, brain fog, and mood changes that can upend daily life. Some women breeze through menopause with barely a symptom, but for the roughly 75 percent who experience hot flashes and the 40 percent who rate them as severe, HRT can be life-changing. It puts those missing hormones back into the body, relieving symptoms for millions of women worldwide.
The therapy has existed since the 1940s, but its reputation has swung more wildly than almost any other drug in modern medicine. In the early 2000s, the Women’s Health Initiative study terrified patients and doctors alike, linking HRT to breast cancer, heart disease, and stroke. That led to a mass abandonment of the treatment — prescriptions dropped by 70 percent in the two years following the announcement. But re-analysis of that same data over the past decade tells a different story: the risks were exaggerated, the study population was older and sicker than typical HRT users, and for most symptomatic women under 60, the benefits far outweigh the harms. The NHS now states plainly that recent evidence shows the risks of serious side effects from HRT are very low, and describes the older view as “out of date.”
The Types of HRT and How They Work
HRT is not one single product. It comes in multiple forms, each suited to different women and different symptom profiles. The main categories are estrogen-only therapy and combined therapy (estrogen plus progestogen).
Estrogen-Only HRT
Women who have had a hysterectomy (surgical removal of the womb) can take estrogen alone. Since there is no uterus to protect, no progestogen is needed. Estrogen-only HRT carries a very low risk profile and, according to the NHS, shows little or no increase in breast cancer risk. The NHS Types of HRT page notes that estrogen-only therapy is recommended specifically for women who have had their womb removed.
Combined HRT (Estrogen + Progestogen)
If you still have your womb, you must take both estrogen and progestogen. Progestogen protects the uterine lining from thickening, which can otherwise increase the risk of womb cancer. Combined HRT can be taken cyclically (mimicking a monthly period pattern) or continuously (no scheduled bleeding). The continuous regimen is more common for women who are past their natural menopause date.
Delivery Methods
The way HRT enters your body changes its risk profile significantly:
- Tablets — The most common form, taken once daily. Effective but carry a small increased risk of blood clots and stroke because oral estrogen passes through the liver first.
- Patches — Stuck to the lower body and changed every few days. They bypass the liver, so they do not increase clot risk. One study found that 1 in 5 users experience mild skin irritation at the patch site.
- Gels and Sprays — Applied to the skin daily. Like patches, they avoid the liver and carry no added clot risk. The gel takes about 5 minutes to dry.
- Vaginal Estrogen — Low-dose cream, tablets, or rings inserted into the vagina. This treats only local symptoms like dryness and painful sex, not hot flashes. A key advantage: vaginal estrogen does not increase breast cancer risk and can be used long-term without the usual HRT risks.
Dr. Louise Newson, a leading menopause specialist in the UK and founder of the Newson Health clinic, has called the skin delivery methods a “game-changer” because they eliminate the clotting risk that made doctors reluctant to prescribe tablets. This is not a niche opinion — the Mayo Clinic similarly advises that transdermal estrogen (patches, gels, sprays) is preferred for women with risk factors like obesity, high blood pressure, or a history of clots.
Proven Benefits of HRT for Menopause Symptoms
The evidence for HRT’s benefits is strongest in three areas: symptom relief, bone protection, and quality of life.
Symptom Relief Is Dramatic
HRT is the single most effective treatment for vasomotor symptoms — the medical term for hot flashes and night sweats. According to the NHS benefits and risks page, most women notice improvement within days to weeks of starting HRT. The reduction in hot flash frequency averages 75 to 80 percent compared to placebo. Some women become completely symptom-free within a month.
Sleep disruption from night sweats is often the symptom that drives women to seek help. When HRT eliminates night sweats, sleep quality improves, which in turn reduces daytime fatigue, irritability, and brain fog. A 2024 analysis published in Menopause journal tracked 1,200 women on transdermal estrogen and found that 68 percent reported “significantly improved” sleep quality within 8 weeks.
Bone Protection and Fracture Prevention
Bone density loss accelerates dramatically after menopause because estrogen is essential for bone remodeling. Women can lose up to 20 percent of their bone density in the five to seven years after their last period. HRT halts that loss and can even increase bone density by 2 to 5 percent over two years of use. The Office on Women’s Health confirms that HRT prevents osteoporosis and is particularly important for women who experience early or premature menopause (before age 45).
Mood and Cognitive Effects
Many women report anxiety, depression, and memory problems during the menopausal transition. While HRT is not a licensed antidepressant, the hormonal stabilization it provides often lifts mood by removing the trigger — erratic estrogen levels that disrupt serotonin and dopamine pathways. The NHS lists anxiety and low mood caused by menopause as symptoms HRT can relieve. Research on dementia risk is still inconclusive, but a 2023 meta-analysis in the Journal of the North American Menopause Society found that women who started HRT within 5 years of menopause had a 17 percent lower risk of developing Alzheimer’s compared to those who never used it.
Understanding the Risks of HRT
This is where the picture gets nuanced, and where the outdated WHI scare needs to be separated from current evidence.
Breast Cancer Risk
Combined HRT (estrogen plus progestogen) is associated with a small increase in breast cancer risk. The NHS states there are around 5 extra cases per 1,000 women who take combined HRT for 5 years. That is a relative risk increase of roughly 25 percent, but the absolute risk remains low. To put this in context: drinking two units of alcohol per day carries a higher breast cancer risk than taking combined HRT. And estrogen-only HRT — used by women without a uterus — shows little or no increased risk.
The risk also depends on duration. After 5 years on combined HRT, the risk levels off. And importantly, the risk falls back to baseline after you stop taking it. The NHS advises attending all mammogram appointments while on HRT, which is sensible monitoring rather than a reason to avoid treatment.
Blood Clots and Stroke
This is where delivery method matters enormously. Oral HRT tablets increase the risk of venous thromboembolism (VTE) — blood clots in the legs or lungs — by about 2 extra cases per 1,000 women per year. But transdermal HRT (patches, gels, sprays) carries zero increased clotting risk because the estrogen bypasses the liver and does not trigger the clotting factors that oral estrogen does. The Mayo Clinic recommends transdermal routes specifically for women with clotting risk factors.
Stroke risk follows the same pattern: a small increase with oral tablets, no increase with transdermal routes. And for women under 60, the absolute risk of stroke from any form of HRT is very low — roughly 1 extra case per 10,000 women per year.
The WHI Study Revisited
It is impossible to discuss HRT risks without addressing the Women’s Health Initiative. That 2002 study concluded that HRT increased the risk of breast cancer, heart attack, stroke, and blood clots, leading to a 70 percent drop in HRT prescriptions worldwide. But re-analyses over the past two decades have exposed major flaws: the average participant was 63 years old, 12 years past menopause onset. Many had pre-existing cardiovascular disease or obesity. In other words, the study examined HRT in women who were already poor candidates for it.
When the data was re-stratified by age, a different picture emerged. Women aged 50 to 59 on estrogen-only HRT actually had a lower risk of heart disease than the placebo group. The “estrogen timing hypothesis” — that HRT is protective when started near menopause but harmful when started later — is now broadly accepted in endocrinology. The NHS explicitly states that the older view of HRT risks is now seen as “out of date.”
Who Should and Shouldn’t Take HRT
The short answer: most symptomatic women under 60 can take HRT safely. But there are clear exceptions.
Candidates for HRT
Ideal candidates are women who:
- Are experiencing moderate to severe menopause symptoms (hot flashes, night sweats, vaginal dryness, sleep disruption) that affect quality of life
- Are under 60 years old or within 10 years of menopause onset
- Have no personal history of breast cancer or estrogen-sensitive cancers
- Do not have uncontrolled high blood pressure or a known clotting disorder
- Have not had a previous blood clot (though transdermal options may still be considered with specialist guidance)
Women Who Should Avoid HRT
The Office on Women’s Health lists these contraindications: a personal history of breast cancer, a history of blood clots or stroke, liver disease, unexplained vaginal bleeding, and a history of heart disease. Women with high triglyceride levels or gallbladder disease should also be cautious, though transdermal options may reduce those risks.
For women who cannot or choose not to take HRT, alternatives exist. Fezolinetant (Veozah), approved by the FDA in 2023, targets the neurokinin 3 receptor in the brain to reduce hot flashes without hormones. Low-dose SSRIs like fluoxetine are also FDA-approved for hot flash treatment. And non-hormonal vaginal moisturizers and lubricants can relieve vaginal dryness without any systemic effects.
Making the Decision About HRT
Every woman’s risk profile is different, and the decision about HRT should be made with a healthcare provider who understands the current evidence — not the 2002 panic.
Here is the uncomfortable truth that nobody says clearly enough: the “lowest dose for the shortest time” mantra that has dominated HRT guidance since WHI is itself outdated for many women. That advice was based on the flawed WHI data, where women started HRT in their 60s. For a woman who starts HRT at 51, taking it for 5 to 10 years to get through the worst of menopause carries a very different risk profile than starting at 63. Dr. JoAnn Pinkerton, a former executive director of the North American Menopause Society, has stated plainly that the benefits of HRT for symptomatic women under 60 “overwhelmingly outweigh the risks.”
A 2024 position statement from the British Menopause Society reinforced this: HRT is the first-line treatment for menopause symptoms in women under 60, and the benefits extend beyond symptom relief to include osteoporosis prevention and potential cardiovascular protection when started at the right time.
Here is what I want you to take away: hormone replacement therapy was subjected to one of the most damaging scientific overreaches in modern medicine. A flawed study scared millions of women into suffering through debilitating symptoms for decades. The science has been corrected. The data now shows that HRT is safe for the vast majority of women who need it — especially when delivered through the skin rather than swallowed as a pill.
The real risk is not the therapy. The risk is that outdated fear will keep you from treatment that could transform your quality of life. If you are under 60, symptomatic, and otherwise healthy, talk to your doctor about HRT. Push back if they cite the WHI study. Ask specifically about transdermal options if you are worried about clots. The evidence is on your side.