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Anastrozole (Arimidex)

Find out what anastrozole is, how you have it and other important information about having anastrozole.

Anastrozole is a cancer treatment drug and is also known by its brand name, Arimidex.

It is a treatment for post menopausal women with breast cancer that is hormone sensitive.

How anastrozole works

Anastozole lowers the amount of oestrogen in the body. The female sex hormones oestrogen and progesterone stimulate many breast cancers to grow. Lowering the level of oestrogen can stop or slow the growth of breast cancer cells.

Anastrozole blocks a process called aromatisation that changes sex hormones called androgens into oestrogen. This happens mainly in the fatty tissues, muscle and the skin and needs a particular enzyme called aromatase.

How you have it

You have anastrozole as tablets.

Try to take it at the same time each day. Swallow the tablet whole with a drink of water. You can take it before, with, or after food.

If you accidentally take more anastrozole than you should, let your doctor know straight away.

If you forget a dose, continue with the next dose as normal. Don't take an extra dose to make up for the missed one.

Taking tablets

You must take tablets and capsules 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.

When you have anastrozole

You take anastrozole once a day. Try to take it at the same time each day. It is a long term treatment and you usually need to take it for several years.

Tests during treatment

You have blood tests before starting treatment and during your treatment. They check your levels of blood cells and other substances in the blood. They also check how well your liver and kidneys are working.

Side effects

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

This treatment might harm a baby developing in the womb. It is important not to become pregnant or father a child while you are having treatment and for a few months afterwards. Talk to your doctor or nurse about effective contraception before starting treatment.

Breastfeeding

Don’t breastfeed during this treatment because the drug may come through in your breast milk.

Treatment for other conditions

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

Anastrozole for men

Anastrozole might sometimes be used to treat breast cancer in men. Breast cancer is very rare in men. So very little is known about the side effects of this drug in men. Doctors expect the effects to be similar to those listed on this page.

Lactose intolerance

This drug contains lactose (milk sugar). If you have an intolerance to lactose, contact your doctor before taking this medicine.

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

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