HRT and hormone testing in perimenopause

Usually no. For women over 45 with typical symptoms, NICE recommends diagnosing perimenopause and menopause without laboratory tests, and hormone levels swing too much in perimenopause for one result to be dependable.¹,⁴ Hormone replacement therapy (HRT, also called menopause hormone therapy) is a prescription treatment that replaces some of the estrogen your body is making less of. The Menopause Society's 2022 position statement says its benefits outweigh its risks for most healthy symptomatic women who are younger than 60, but whether it is right for you is a decision to make with a doctor.⁹

Do you need a hormone test to know you are in perimenopause?

For most women, no. Cleveland Clinic states that hormone testing is not necessary to diagnose perimenopause, which is usually identified from your age, symptoms and medical history.³

The reason is the hormone at the center of most tests. Follicle-stimulating hormone (FSH) is the signal your brain sends to prompt the ovaries to produce estrogen. As ovarian function declines, the body raises FSH to try to get more estrogen out of them.⁴ But the number swings. Harvard Health reports that day-to-day hormone levels can fluctuate dramatically, so a single reading is not dependable, and FSH is also typically high just before ovulation, so a high result does not by itself mean menopause is near. Home FSH kits share the problem: they can measure the hormone, but not tell you how close to menopause you are.²,⁴,⁵ A normal result does not rule perimenopause out, and a high one does not confirm it.

There are situations where tests are part of the picture. NICE says an FSH test may be considered for women aged 40 to 45 with menopausal symptoms, including a change in their menstrual cycle, and that premature ovarian insufficiency under 40 should never be diagnosed from a single blood test.¹ NICE also says not to use an FSH test to diagnose menopause in women taking combined hormonal contraception.¹ Doctors may check thyroid levels, since an overactive thyroid can cause similar symptoms.² For a plain-language look at what the common tests measure, see everything you need to know about hormone testing.

What is HRT?

HRT uses hormones, mainly estrogen, to replace some of what the body stops making.⁶ Mayo Clinic describes systemic estrogen (a pill, patch, gel, spray or ring) as the most effective treatment for hot flashes and night sweats, and low-dose vaginal estrogen as mainly treating vaginal and urinary symptoms.⁶

If you still have a uterus, estrogen is usually combined with a progestogen, because estrogen alone can thicken the uterine lining and raise the risk of endometrial cancer. The progestogen lowers that risk. If you have had your uterus removed, you may not need one.⁶,⁷ The Menopause Society notes that transdermal routes (such as patches) and lower doses may reduce the risk of blood clots and stroke, a point to raise with your doctor.⁹

The NHS also notes that taking HRT during perimenopause can make periods more regular.⁸ HRT is not contraception, though. NICE states that HRT is not a contraceptive,¹ and our guide to pregnancy and contraception in perimenopause explains why that matters.

What did the Women's Health Initiative show, and why has the story changed?

Many women have heard that HRT is dangerous. Much of that traces back to one trial.

In July 2002, the US National Heart, Lung, and Blood Institute stopped the estrogen-plus-progestin arm of the Women's Health Initiative (WHI) early, after an average of 5.2 years of follow-up. Women taking the combination had a higher risk of invasive breast cancer, and higher rates of coronary heart disease, stroke and pulmonary embolism, than those on placebo, though they also had fewer hip fractures and colon cancers.¹⁷

What took longer to land was who was in the study. The average WHI participant was about 63, more than a decade past the average age of menopause.¹³,¹⁶ Later analyses broke the results down by age. In the 2013 JAMA overview, a composite measure of adverse events with combined therapy showed 12 more events per 10,000 women per year at ages 50 to 59, against 38 more at 70 to 79. With estrogen alone it was 19 fewer at 50 to 59 and 51 more at 70 to 79.¹⁶ The same authors still concluded that hormone therapy is not supported for chronic disease prevention.¹⁶

That age pattern is often called the timing hypothesis: the balance of benefits and risks appears to differ with your age and years since menopause. The Menopause Society's 2022 statement says benefits outweigh risks for most healthy symptomatic women younger than 60, and that breast cancer risk does not rise appreciably with short-term estrogen-progestogen use. It also notes limited data on use past 60 or 65.⁹ Mayo Clinic gives a similar picture, and adds that starting later raises the risk of serious complications.⁶

In November 2025, the US Food and Drug Administration announced it was beginning to remove the broad boxed warnings from menopausal hormone therapy products, working with manufacturers to remove label references to cardiovascular disease, breast cancer and probable dementia. It said it was not seeking to remove the boxed warning for endometrial cancer on systemic estrogen-alone products, and that its labeled recommendation is to start HRT within 10 years of menopause onset or before 60 for systemic use.¹³ In February 2026, the FDA announced approved labeling changes for the first six products.¹⁴ The Menopause Society welcomed the removal of the warning on low-dose vaginal estrogen, while saying systemic estrogen still carries potential risks in certain individuals, and that risks are greater when started in older women.¹⁰

The short version: the risks were not invented, and they are not gone. They depend on age, type, dose and your health history. Mayo Clinic lists a possible increased risk of heart disease, stroke, blood clots, breast cancer, gallbladder disease and endometrial cancer.⁶ One observational study of perimenopausal estrogen users found no significantly higher rates of breast cancer, heart attack or stroke, though its investigators note biases such as healthy user bias.¹²

Are bioidentical hormones safer?

The word "bioidentical" suggests a gentler option. The evidence does not say that.

The Menopause Society says most people use the term for hormones with the same chemical and molecular structure as the body's own, and that it began as a marketing label for custom-compounded products.¹¹ Two different things are sold under one name. FDA-approved products with that structure exist, are sold at regular pharmacies, and have been evaluated for safety and effectiveness. Mayo Clinic notes that many FDA-approved hormone medicines already contain bioidentical hormones.¹¹,¹⁵,¹⁸ Compounded versions are mixed by a pharmacy to a prescription. They are not FDA-approved, and their purity, safety and effectiveness are less certain.¹⁹

On the question of safety, the positions are consistent. The Menopause Society says custom-compounded hormones are not safer or more effective than approved bioidentical hormones, and may not contain the prescribed amounts.¹¹ The FDA says it does not have evidence that compounded bioidentical hormones are safe and effective.¹⁵ Mayo Clinic says research has not shown they offer benefits over commercially made medicines,¹⁸ and NICE says their efficacy and safety are unknown.¹

Some providers adjust compounded doses using saliva tests, but Mayo Clinic says hormone levels in saliva do not reflect blood levels or correspond to menopause symptoms.¹⁸ And an approved bioidentical product is still hormone therapy, which in general can increase the risk of blood clots, stroke and gallbladder disease.¹⁹

What can you expect when you start HRT?

Responses vary. Some women notice changes within a few weeks, while for others it can take 8 to 12 weeks or more. There is no guarantee of relief.

Mild, temporary side effects can include breast tenderness or swelling, headaches, bloating, water retention, mood swings, and spotting or changes in your bleeding pattern. NICE notes that unscheduled vaginal bleeding is a common side effect within the first three months, and that it should be reported at the three-month review, or promptly if it appears after that.¹ NICE also recommends reviewing each treatment for short-term symptoms at three months to assess how well it works and how well you tolerate it, then yearly.¹ Doctors may adjust the dose or change the form. A record of your symptoms and side effects, in a notebook or an app, gives you something concrete to bring to those reviews.

How do you decide whether HRT is right for you?

That is a decision for you and a doctor, not a checklist. Mayo Clinic says the risks depend on your age, the type and dose of hormones, whether a progestogen is used, and your personal health history, including cancer, heart disease, clotting, liver disease and osteoporosis.⁶ Worth raising: how much your symptoms disrupt daily life, your own and your family's history of cancer, clots, stroke and heart disease, and how long it has been since your last period.

If HRT is not suitable or not what you want, there are other routes. Mayo Clinic lists cognitive behavioral therapy, clinical hypnosis, nonhormone prescription medicines for hot flashes, and vaginal moisturizers or lubricants.⁶ We cover these in natural and lifestyle alternatives to HRT.

When to see a doctor

See a healthcare provider if symptoms are significantly disrupting your sleep, work or relationships, if symptoms start before 40, or you are 40 to 45 and your cycle is changing, or if you bleed after 12 months without a period.⁸ If you are on HRT and have unscheduled bleeding, NICE says to report it at your three-month review, or promptly if it appears after the first three months.¹

Read next: Everything you need to know about hormone testing, Natural and lifestyle alternatives to HRT