HRT: What It Is, What It Does, and the Truth About the Risks

Hormone replacement therapy has been surrounded by more confusion, more outdated advice, and more patient harm through under-prescription than almost any other treatment in modern medicine. Here is what the current evidence actually says — including what most women are never told about the benefits.

In 2002, a large American study called the Women's Health Initiative published results that caused a generation of women to be denied effective perimenopause treatment. The study suggested that HRT significantly increased breast cancer risk, and the media coverage was immediate and overwhelming. Millions of women stopped their HRT overnight. Millions more who would have benefited from it were never prescribed it. GPs who had been enthusiastic prescribers became cautious. The cultural narrative around HRT became one of danger.

The problem is that the study was misinterpreted and its findings misapplied. In the years since, the evidence has been substantially revised, re-analysed, and recontextualised — and the current medical consensus, reflected in the NICE 2024 guideline, tells a considerably more nuanced story than the one most women have heard. We are still, in 2026, living in the aftermath of that original misinterpretation — still managing a crisis of under-prescription that is causing real harm to real women.

This article lays out what the current evidence actually says, clearly and without qualification.

What Is HRT?

Hormone replacement therapy is exactly what it sounds like: it replaces the hormones — primarily oestrogen and progesterone — that the body produces in decreasing quantities during perimenopause and menopause. The NHS describes HRT as a safe and effective treatment for most people going through menopause and perimenopause. That framing is important: not as a last resort, not as a treatment for only the most severe symptoms, but as a safe and effective standard treatment for a standard physiological transition.

There are several distinct components of HRT, and understanding what each does and why it is used is essential context for any conversation about risk.

Oestrogen is the primary hormone being replaced — the one whose decline drives the majority of perimenopause symptoms. It is available in multiple forms: patches applied to the skin, gels applied to the thigh or arm, sprays, and tablets. Transdermal oestrogen — patches and gels, which deliver oestrogen through the skin into the bloodstream, bypassing the liver — is generally preferred in current guidelines. The reason is significant: oral oestrogen, because it passes through the liver, is associated with a small increased risk of blood clots. Transdermal oestrogen does not carry this risk, because it enters the bloodstream directly without liver metabolism.

Progesterone is added to oestrogen for women who have a uterus — its role is to protect the womb lining from the proliferative effect of oestrogen, which without progesterone would significantly increase the risk of womb cancer. Progesterone comes in two forms with meaningfully different risk profiles: micronised progesterone (sold under the brand name Utrogestan), which is body-identical — chemically identical to the progesterone the body produces — and synthetic progestogens (such as norethisterone and levonorgestrel), which are synthetic compounds that mimic progesterone but are not chemically identical to it. The body-identical form, micronised progesterone, is now preferred in current guidelines because it carries a lower risk profile than synthetic progestogens, including a lower breast cancer risk.

Testosterone is the third component that is increasingly being recognised as important in women's HRT. Women produce testosterone in the ovaries and adrenal glands throughout their lives, and it plays a significant role in energy, libido, cognitive function, muscle mass, and motivation. Testosterone therapy for women is licensed in the UK for hypoactive sexual desire disorder, and is used off-label for other symptoms including energy and brain fog. It is prescribed as a gel or cream applied to the skin, and requires blood level monitoring to ensure appropriate dosing.

What the NICE 2024 Guideline Actually Says

The 2024 NICE guideline on menopause is the most important document in UK women's health for understanding the current evidence-based position on HRT. Its key statements are worth reading directly rather than through layers of summary.

The guideline recommends offering HRT to people with vasomotor symptoms (hot flushes and night sweats) associated with menopause. It also highlights that while it is important that people know about the risks associated with HRT, it is equally important they are made aware that HRT is unlikely to increase or decrease their overall life expectancy. This is a striking statement, and one that receives very little public attention: the overall mortality picture for HRT is neutral. The risk framing that dominates the public conversation — that HRT is a dangerous drug that shortens lives — is not supported by the current evidence.

The guideline also recommends that antidepressants should not be offered as first-line treatment for low mood or anxiety associated with perimenopause, and that HRT should be discussed before antidepressants are prescribed for these symptoms. This is a direct and specific reversal of the practice that has become routine in many GP surgeries — a practice that has left countless women taking antidepressants for hormonal symptoms that HRT would address more effectively and with fewer side effects.

The Breast Cancer Question — Answered Honestly

The breast cancer risk associated with HRT is the question that dominates — and often ends — conversations about treatment. Here is an honest and complete answer.

Combined HRT — oestrogen plus a synthetic progestogen — does carry a small increased risk of breast cancer. The size of this risk is frequently misrepresented, however. The absolute risk increase associated with five years of combined HRT is comparable to the risk increase associated with drinking one glass of wine per day, or with being overweight. These are risks that most women accept as part of everyday life without giving them significant thought. The HRT risk, presented in the same terms, is not the catastrophic danger that public perception suggests.

Body-identical micronised progesterone, which is now the recommended form, carries a significantly lower breast cancer risk than synthetic progestogens. The studies that produced the most alarming breast cancer risk figures used older synthetic progestogens that are no longer preferred in current prescribing. The risk profile of modern, body-identical HRT is considerably more favourable than the historical data suggested.

Oestrogen-only HRT — for women who have had a hysterectomy and therefore do not need progesterone — does not increase breast cancer risk. Some studies suggest it may slightly reduce it. This is almost never communicated to women, who tend to assume that all forms of HRT carry the same risk profile.

Transdermal oestrogen does not increase blood clot risk. Oral oestrogen carries a small increased risk of blood clots, which is why transdermal forms are now preferred. If you have been told you cannot take HRT because of blood clot risk, it is worth asking specifically whether transdermal oestrogen has been considered — because the risk profile is meaningfully different.

The Benefits That Are Almost Never Mentioned

The conversation about HRT in most clinical settings focuses almost entirely on risks. The benefits — which are substantial and which the NICE guideline explicitly highlights — are rarely communicated with the same clarity or emphasis.

HRT has well-documented protective effects on bone density. Oestrogen is critical to bone remodelling — its decline during perimenopause accelerates bone density loss and increases osteoporosis risk. HRT taken during perimenopause and early postmenopause significantly reduces this risk. For women with a family history of osteoporosis, or for those at elevated risk, this benefit is clinically significant.

HRT started during perimenopause or within ten years of the last menstrual period has documented cardiovascular protective effects. The timing hypothesis — supported by the SWAN cohort and other longitudinal studies — suggests that early HRT initiation reduces cardiovascular risk, while HRT started many years after menopause may not carry the same benefit (and was the basis for the WHI findings that were misapplied to all women). For women in their 40s and early 50s, HRT is likely to have a cardiovascular protective effect, not a harmful one.

The cognitive benefits of HRT are an active area of research. Current evidence suggests that oestrogen's neuroprotective effects — its support for acetylcholine production, hippocampal function, and neuronal communication — are most significant when HRT is initiated close to the onset of perimenopause. This "critical window" for cognitive protection is another argument for early, rather than delayed, treatment.

What to Ask Your GP

Going to a GP appointment about HRT without preparation puts you at a significant disadvantage. Many GPs are not up to date with the current evidence — a 2023 survey found that many healthcare professionals still hold concerns about HRT that are based on the outdated post-WHI research rather than the current guideline. This is not a criticism of GPs — medicine is vast and perimenopause has historically been underprioritised in medical education. But it means that the best outcomes for women often come from informed, prepared patients who can reference specific guidance.

Questions worth asking: Am I eligible for HRT based on my symptom picture and medical history? If there are concerns about my eligibility, can you explain them specifically? If I am eligible, what type, dose, and delivery method would you recommend? Should we consider adding testosterone? What should I expect in the first weeks? When will we review, and what will we be assessing at review?

If you are told HRT is too risky without a specific individual risk assessment — without a clinician walking through your personal medical history and family history — this is a general dismissal, not a clinical decision. You are entitled to ask for that specific assessment. If you are told your blood tests are normal and therefore you do not need HRT, this misapplies the NICE guideline: perimenopause is a clinical diagnosis based on symptoms, not a biochemical one based on blood levels. And if you remain concerned that you are not being heard, you are entitled to a second opinion or a referral to a menopause specialist.