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What is anastrozole?

Medication that stops the conversion of testosterone into oestrogen.

It's also known as Arimidex.

What does anastrozole do?

Who can have anastrozole?

  • You usually need to be at least 18

  • You cannot have this if you are pregnant, or might become pregnant

How long does anastrozole last?

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

Why might I want anastrozole?

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, but it can also be used to reduce breast growth 1 or stop menstruation.

Why might I not want anastrozole?

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

How does it work?

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.


  1. 1.
    Electronic Medicines Compendium (2016) “Anastrozole 1 mg film-coated tablets.” Link

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