Decorative image

Letrozole (Femara)

Find out what letrozole is, how you have it and other important information about taking letrozole.

Letrozole is a type of hormone therapy drug. It is a treatment for breast cancer in women who have had their menopause. It is also called Femara.

How letrozole works

Letrozole lowers the levels of the female sex hormone oestrogen in the body. Oestrogen stimulates some breast cancers to grow. These breast cancers are called hormone sensitive or hormone receptor positive. Letrozole can stop or slow the growth of these cancers.

Letrozole only works in women who have had their menopause.

After the menopause, women don't produce oestrogen from their ovaries. But they still produce a small amount by using an enzyme called aromatase which turns other sex hormone called androgens into oestrogen. This change happens mainly in fatty tissue, muscle and the skin. Letrozole is a type of drug called an aromatase inhibitor. It blocks aromatase so that it can't change the androgen into oestrogen.

How you have letrozole

You have letrozole as a tablet once a day. It is best to take the tablets at the same time each day. You can take them with or without food.

Taking your tablets

You must take tablets according to the instructions your doctor or pharmacist gives you.

You should take the right dose, not more or less.

Never stop taking a cancer drug without talking to your specialist first.

If you accidentally take too much letrozole (Femara), contact a doctor or hospital straight away. You might need medical treatment. 

If you forget to take a dose and it is almost time for your next dose (for example, within 2 or 3 hours), skip the dose you missed and take your next dose when it is due. Otherwise, take the dose as soon as you remember, and then take the next dose at the normal time. Don't take a double dose.

Tests during treatment

You might have blood tests before starting treatment and during your treatment. They check your general health and might check your levels of blood cells and other substances in the blood.

Important information

Other medicines, foods and drink

Cancer drugs can interact with some other medicines and herbal products. Tell your doctor or pharmacist about any medicines you are taking. This includes vitamins, herbal supplements and over the counter remedies.

Pregnancy and contraception

You should only take this drug if you have been through your menopause. When you first go through the menopause there can still be a chance that you could become pregnant. This drug may harm a baby developing in the womb. It is important to not to become pregant while you are having treatment and for a few months afterwards. So, even if you have had your menopause, talk to your doctor or nurse about effective contraception before stating treatment. 

Treatment for other conditions

Always tell other doctors, nurses, pharmacists or dentists that you’re having this treatment if you need treatment for anything else, including teeth problems.

Side effects

More information about this treatment

For further information about this treatment go to the electronic Medicines Compendium (eMC) website.

You can report any side effect you have to the Medicines Health and Regulatory Authority (MHRA) as part of their Yellow Card Scheme.

Information and help

Dangoor sponsorship

About Cancer generously supported by Dangoor Education since 2010.