What effects does it have?

What is it?

Medication that stops the conversion of testosterone into oestrogen.

It's also known as Arimidex.

How long does it last?

Anastrozole is a pill that needs to be taken daily. The effects will stop in days if you stop taking the medication.

More information

The human body naturally converts excess testosterone into oestrogen. Anastrozole works by stopping “aromatase”, a chemical that the body uses as part of this process. Taking anastrozole can reduce the amount of oestrogen in your body.

Anastrozole is normally used in breast cancer patients to slow the growth of some tumours. However, it can also be used to reduce breast growth 1 or stop menstruation.

As anastrozole can have a number of side effects, in the UK GnRH agonists are usually used to stop the production of oestrogen instead.


  1. 1 Electronic Medicines Compendium (2016) “Anastrozole 1 mg film-coated tablets.” [online] Available from: https://www.medicines.org.uk/emc/medicine/33627

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Page last updated: August 2017