Hormone Replacement Therapy Explained: What Actually Works

You went to your GP with a list. Night sweats that soak through the mattress. A belly that appeared without explanation. A brain that loses words mid-sentence. You left with a leaflet and the phrase "it's completely normal at your age."

It is common. That's not the same as normal, and it's not the same as nothing can be done. What's happening in your body right now has a name, a mechanism, and a set of real interventions that work for most women who try them. Hormone replacement therapy is the one your doctor may have mentioned briefly, or avoided entirely. This article gives you the actual information.

HRT is not a magic switch. It is also not the cancer risk your mother warned you about in 2002, based on a study that has since been reanalyzed and substantially revised. What it is, in 2024, is the most evidence-supported treatment available for perimenopausal and menopausal symptoms — and the details matter enormously.

What Is Actually Happening Inside Your Body

Your ovaries have been producing estrogen and progesterone since puberty. As you move through perimenopause — which can begin as early as your mid-40s — ovarian function becomes erratic. Estrogen doesn't drop in a straight line. It fluctuates wildly before it falls, which is why some months feel fine and others feel catastrophic.

Estrogen receptors exist throughout your body: in your brain, your bones, your cardiovascular system, your skin, your muscles, and your gut. When estrogen becomes unpredictable, all of those systems register the disruption. The 3am wake-ups happen because your thermoregulatory system, which estrogen helps stabilize, loses its calibration. The belly fat accumulates because falling estrogen shifts where your body stores fat — away from your hips and toward your abdomen. The brain fog is not imaginary. Estrogen plays a direct role in acetylcholine production, a neurotransmitter involved in memory and cognitive function.

Progesterone's decline matters too. This hormone promotes sleep and has a calming effect on the nervous system. Losing it contributes to the anxiety and sleep disruption many women experience before they ever identify perimenopause as the cause.

What the Research Actually Shows

The 2002 Women's Health Initiative (WHI) study caused an enormous and lasting panic about HRT. It reported increased risks of breast cancer, heart disease, and stroke. Millions of women stopped treatment overnight. What followed was 20 years of researchers unpicking what that study actually showed — and what it got wrong.

The WHI used synthetic progestins combined with conjugated equine estrogen, given orally, to women who were on average 63 years old and already a decade past menopause. The findings from that population do not map directly onto a 54-year-old woman starting HRT within a few years of her last period.

A 2019 reanalysis published in The Lancet did confirm a modest increase in breast cancer risk associated with combined HRT (estrogen plus progestogen), and that finding warrants honest discussion. The absolute risk increase for a woman taking combined HRT for five years is approximately 4 additional cases per 1,000 women — comparable to the risk increase associated with drinking two units of alcohol per day or being overweight. Estrogen-only HRT, used by women who have had a hysterectomy, showed no significant increase in breast cancer risk in the same data.

A 2020 paper in JAMA Internal Medicine found that women who begin HRT within ten years of menopause onset — the "timing hypothesis" or "window of opportunity" — show cardiovascular benefits rather than harm, including reduced risk of coronary artery disease. The NIH's National Institute on Aging has acknowledged this timing effect in its guidance. Read the NIH overview on menopause and HRT here.

For bone health, the evidence is unambiguous. Estrogen loss accelerates bone density reduction. The British Menopause Society and the NHS confirm that HRT reduces fracture risk and is considered first-line treatment for women at elevated risk of osteoporosis.

For quality of life — sleep, cognitive clarity, mood, sexual function, and physical energy — the evidence base is consistent and strong.

HRT Benefits and Risks: The Honest Summary

Benefits with solid evidence behind them

• Reduction in vasomotor symptoms (hot flashes, night sweats) by 75-90% in most women
• Improved sleep quality, independent of symptom reduction
• Maintained bone density and reduced fracture risk
• Improved mood and reduced depressive symptoms in perimenopausal women
• Reduced genitourinary symptoms (vaginal dryness, urinary urgency)
• Cognitive benefits when started early in menopause transition
• Preservation of muscle mass alongside resistance training

Risks that require individual assessment

• Small increased risk of breast cancer with combined HRT taken for more than five years
• Small increased risk of venous thromboembolism (blood clots) with oral estrogen — this risk is not present with transdermal (skin patch or gel) estrogen
• Irregular bleeding in the first few months, which requires investigation if it continues
• Not appropriate for women with hormone-sensitive breast cancer, untreated endometrial cancer, unexplained vaginal bleeding, or active blood clot conditions

The risk picture is individual. A woman with a strong family history of breast cancer has a different calculation than a woman whose primary concern is osteoporosis prevention. This is exactly the conversation to have with a doctor who actually engages with the evidence.

Menopause HRT Options: What You Can Actually Choose

Not all HRT is the same. The type, route of delivery, and the specific hormones used all affect both efficacy and risk profile.

Estrogen-only HRT

For women who have had a hysterectomy. Available as tablets, patches, gels, or sprays. Carries no meaningful increased breast cancer risk based on current evidence.

Combined HRT (estrogen plus progestogen)

For women with a uterus. Progestogen protects the uterine lining from the growth-stimulating effect of estrogen alone. The type of progestogen matters. Micronized progesterone (body-identical, marketed as Utrogestan) carries a lower risk profile than older synthetic progestins and is now widely available on prescription in the UK and US.

Routes of delivery

Transdermal estrogen (patches, gels, sprays applied to skin) bypasses the liver, which is why it does not carry the blood clot risk associated with oral estrogen. For most women, transdermal is now considered the preferred route. Patches are changed every 3-4 days. Gels are applied daily.

Oral tablets are effective but carry slightly higher cardiovascular risk due to first-pass liver metabolism. Still appropriate for many women who prefer this form.

Vaginal estrogen (cream, pessary, or ring) is low-dose, local, and does not carry systemic risks. It addresses genitourinary symptoms and can be used alongside systemic HRT or on its own. It is safe for long-term use and often underprescribed.

Testosterone

Frequently overlooked in women's HRT. Testosterone declines in women during perimenopause and affects libido, energy, and muscle mass. NICE guidelines (2015, updated 2019) recommend offering testosterone to menopausal women whose low libido does not respond to standard HRT. It is typically prescribed as a cream or gel applied to the skin at doses much lower than those used in men.

Specific Dosages: What to Expect Your Doctor to Discuss

Dosage is not one-size-fits-all, but here are the standard starting points used in UK and US clinical practice.

Estradiol gel: 0.5-1.0mg per day is a typical starting dose, equivalent to one pump of Oestrogel. Many women need 1.5-2mg for adequate symptom control. Dose is adjusted based on symptom response over 8-12 weeks.

Estradiol patches: Starting at 25-50 micrograms per day, with adjustment to 75-100 micrograms if symptoms persist.

Micronized progesterone (Utrogestan): 100mg per night for continuous combined HRT, or 200mg for 12-14 days per cycle in sequential regimens for perimenopausal women still having periods.

Testosterone cream/gel: Doses for women are typically around one-tenth of male doses — 5-10mg testosterone per day is common. Blood levels should be checked after 3-6 months.

As always, talk to your doctor before making changes to your supplement routine or exercise program — especially if you have existing health conditions. Dosage decisions require individual assessment, particularly if you have conditions affecting liver function, blood pressure, or clotting.

What to Expect in the First 30 Days

Most women do not feel dramatically different in the first two weeks. This is not failure — it is pharmacology.

Weeks 1-2: Some women notice improved sleep within days. Others notice nothing, or notice that their symptoms feel temporarily more prominent as the body adjusts. Breast tenderness and bloating are common in this window and typically settle.

Weeks 2-4: Night sweats begin to reduce in frequency and intensity for most women. Mood often lifts before physical symptoms fully resolve — the brain's estrogen receptors respond relatively fast. Energy levels start to stabilize.

Weeks 4-8: Clearer cognitive function for many women. Hot flash frequency continues to decline. Vaginal symptoms take longer — expect 8-12 weeks for meaningful improvement in genitourinary symptoms.

3-6 months: Full symptom benefit is typically established in this window. This is also when dosage review is appropriate if symptoms persist.

Irregular bleeding is common in the first 3-6 months with sequential HRT. Any bleeding that begins after 12 months of no periods (if you are on continuous combined HRT) requires investigation.

Common Mistakes and How to Avoid Them

Stopping too soon. Women discontinue HRT after 2-3 weeks because they don't feel a dramatic change. The 8-12 week mark is when a real assessment of efficacy is possible.

Using the wrong route. Oral estrogen when transdermal was indicated (particularly in women with migraines, elevated blood pressure, or clot risk factors). If your doctor prescribes tablets without discussing alternatives, ask specifically about patches or gel.

Incorrect progesterone type. If you are prescribed a synthetic progestin (medroxyprogesterone acetate, norethisterone) and tolerate it poorly — or are concerned about risk — ask whether micronized progesterone is appropriate for you. It often is.

Ignoring testosterone. If fatigue, low libido, and muscle loss persist after estrogen is optimized, testosterone deserves a conversation. Many GPs do not raise it proactively.

Not monitoring. HRT is not a one-time prescription. Annual review is standard practice, covering blood pressure, symptom status, and continued appropriateness.

When Results Are Not as Expected

Some women start HRT, follow the protocol, wait the full 12 weeks, and still feel only partial improvement. This happens, and it has explanations worth pursuing.

Absorption issues. Transdermal estrogen absorption varies by individual. A blood test measuring serum estradiol levels (aim for 200-400 pmol/L for symptom control, though this varies) can confirm whether you are absorbing the dose adequately.

Thyroid dysfunction. Hypothyroidism produces symptoms that overlap significantly with menopause: fatigue, weight gain, brain fog, cold sensitivity. If your HRT response is poor, request a full thyroid panel including TSH and free T4, not just TSH alone.

Sleep disorders. HRT improves sleep disruption caused by vasomotor symptoms, but if you have underlying sleep apnea or insomnia with a behavioral component, it will not fully resolve those. Both are worth investigating independently.

Dose that needs adjustment. The starting dose is a starting dose. If symptoms persist at 12 weeks, a dose increase is clinically appropriate, not a sign that HRT is not working for you.

Androgen deficiency. If fatigue, low motivation, and poor muscle response to exercise continue despite good estrogen levels, testosterone levels warrant testing.

Realistic Expectations

HRT will not reverse ten years of aging. It will not automatically restore the body composition you had at 40. What it does, for most women who use it appropriately, is remove a significant hormonal obstacle so that the other work you are doing — eating well, training, sleeping, managing stress — can actually have an effect.

Most women notice meaningful improvement in core symptoms within 8-12 weeks. The full picture emerges at 6 months. Some women need dose adjustment, a different delivery route, or additional hormones to get there. That process takes time and requires a doctor who will engage with the evidence rather than dismiss your ongoing symptoms as acceptable.

The question is not whether HRT is right for every woman. It is whether the risk-benefit calculation, done properly and individually, makes it the right choice for you. For the majority of women in perimenopause and early menopause, without contraindications, the answer is yes.

FAQ

How long does it take for HRT to start working?

Some women notice improved sleep and mood within two weeks. Hot flashes and night sweats typically reduce significantly by weeks four to eight. Cognitive symptoms and energy levels often improve by the three-month mark. Genitourinary symptoms take the longest — expect 8-12 weeks for meaningful change. If you feel no improvement at all by 12 weeks, the dose or delivery method may need adjustment, not abandonment.

Is HRT safe if my mother had breast cancer?

A family history of breast cancer raises your baseline risk, but it does not automatically make HRT contraindicated. The relevant factors include whether the cancer was hormone-receptor positive, how close the family relationship is, and whether you have been tested for BRCA gene variants. Estrogen-only HRT carries substantially lower breast cancer risk than combined HRT. Micronized progesterone appears safer than synthetic progestins in this regard. This is a specific conversation to have with a gynecologist or menopause specialist, not a GP who will default to refusal.

Can I take HRT if I still have periods?

Yes. Perimenopause — the transition phase when cycles become irregular but have not stopped — is actually when symptoms are often most severe. Sequential HRT, where progesterone is taken for part of the month to mimic a cycle, is designed for women who are still menstruating. Continuous combined HRT, which suppresses periods, is typically used after 12 months of no natural periods. Your starting regimen depends on where you are in the transition.