Letrozole, fertility, menopause and sexual health

Letrozole lowers oestrogen by blocking the aromatase enzyme, which makes most of the oestrogen in women after menopause. For this reason it is mainly used in women who are already postmenopausal, or in younger women whose ovaries are switched off with monthly or three-monthly injections or surgery. In a woman whose ovaries are still working, letrozole on its own can actually stimulate the ovaries to release eggs, which is why fertility clinics sometimes use it to help women conceive. So letrozole is not a contraceptive, and pregnancy is possible if the ovaries are active. Letrozole can harm an unborn baby, so if there is any chance of pregnancy you need reliable non-hormonal contraception, such as a copper coil or condoms, during treatment and for a period after stopping that your doctor will advise. Breastfeeding is also not advised. For women who want children in future, the main fertility effects usually come from chemotherapy, age and the years spent on hormone therapy, rather than from letrozole directly. Some women pause hormone therapy after a few years to try for a baby, with their oncologist's agreement. Letrozole also tends to bring on or deepen menopause symptoms, such as hot flushes, night sweats, vaginal dryness, lower sex drive and discomfort during sex. These are common and can be helped, mostly with non-hormonal options. Talking openly with your team about sex and fertility is normal and important.

Not a contraceptive

Letrozole alone can stimulate working ovaries, so pregnancy remains possible.

Pregnancy must be avoided on treatment

Use non-hormonal contraception if there is any chance you could conceive.

Sexual side effects can be helped

Moisturisers, lubricants and support ease dryness and discomfort for many women.

These topics can feel awkward to raise, but they matter to many women and couples.

Fertility cannot be predicted exactly

Age, chemotherapy and years of treatment all play a part, and no test can say for certain whether you will be able to conceive.

Pausing treatment involves trade-offs

Research suggests a planned pause to try for a baby does not appear to raise the short-term risk of return, but longer-term information is still being gathered.

Sexual changes are common

They are not a sign that something is wrong with you or your relationship, and help is available.

What this page cannot tell you

It cannot plan a pregnancy for you. Your oncologist and fertility specialist can.

If you hope to have children, raise it as early as possible, ideally before any treatment starts.

Before treatment

Egg or embryo freezing may be possible. Fertility clinics often add letrozole to the stimulating medicines to keep oestrogen levels lower during this process.

During treatment

Some women, with their oncologist's agreement, pause hormone therapy after a few years, try to conceive, and then restart after the birth and breastfeeding.

After treatment

Your team will advise how long to wait after the last tablet before trying.