How long can you take HRT? What the guidance actually says

Where the five-year rule came from

In 2002 the Women's Health Initiative trial was stopped early and reported increased risks with combined hormone therapy. The findings were communicated in a way that produced a collapse in prescribing worldwide, and a rule of thumb emerged: lowest dose, shortest time, five years maximum.

Subsequent reanalysis changed the picture substantially. The average participant was 63 and more than a decade past menopause, which is not the population typically starting hormone therapy for symptoms. Risks differed considerably by age at initiation, and the estrogen-only arm showed a different and more favourable profile than the combined arm.

The five-year rule was a simplification of a finding that did not support it, and it has outlived the guidance that produced it by two decades.

What guidance says now

NICE states that there is no fixed limit on duration, and that the decision should be reviewed with the woman rather than imposed by a calendar. The Menopause Society position is similar: duration should be individualised, and arbitrary discontinuation at a set time is not supported.

What both recommend is regular review, typically annual, covering whether symptoms would return, how the benefit-risk balance has shifted with age, and whether the type, dose or route should change.

Some risks do accumulate with duration and with age, particularly for combined therapy, which is exactly why review rather than a fixed stop date is the right instrument.

Where a longer duration is actively recommended

For women with premature ovarian insufficiency or early menopause, guidance recommends hormone therapy at least until the average age of natural menopause, around 51.

The reasoning is that this is replacement of hormones the body would ordinarily still be producing, for bone and cardiovascular protection as much as symptoms, and the risk framing from trials in older women does not apply. The same reasoning covers surgical menopause before the natural age.

Local vaginal estrogen is a separate question

Low-dose vaginal estrogen for genitourinary symptoms has minimal systemic absorption and is not subject to the same duration considerations as systemic therapy.

Because genitourinary syndrome of menopause progresses rather than resolving, benefit continues only while treatment continues, and long-term use is generally considered appropriate. Stopping it because of a general rule about hormone therapy duration is applying the wrong rule.

Stopping, if and when you do

Symptoms return in a substantial proportion of women when hormone therapy stops, at any age, which is worth knowing before a trial of stopping so the outcome is not a surprise.

Whether to reduce gradually or stop abruptly is debated and the evidence does not strongly favour either; tapering is often used because it makes returning symptoms easier to distinguish from withdrawal effects.

When to see someone

Ask for an annual review rather than accepting a stop date. If you are told you must stop at five years, it is reasonable to ask which guideline that comes from.

Reasons to review sooner: a new diagnosis of breast cancer, a clot, a stroke or heart attack, new migraine with aura, or any unscheduled bleeding after six months of settled treatment.