skip to main content

What does it do?

Tamoxifen is used to treat breast cancer. Some breast cancers need the hormone oestrogen to grow. Tamoxifen reduces the effects of oestrogen, which slows cancer growth.

Before you start

  • Tell your doctor if you have liver problems, endometriosis or uterine fibroids, or if you have ever had a stroke, 'mini-stoke' or blood clot.
  • Tell your doctor if you are pregnant, planning to become pregnant, or breastfeeding.

How should you take it?

Take tamoxifen regularly as directed with a glass of water.

What if you forget a dose?

If it is nearly time for your next dose, skip the missed dose and take your next dose at the usual time. Otherwise, take the missed dose as soon as you remember. Do not take two doses at the same time.

Can you take other medicines?

Tell your pharmacist or doctor about all medicines or treatments that you may be taking, including vitamins, herbal products (e.g. St John's wort) or recreational drugs.

What side effects might you notice?

Side EffectsRecommended action

Symptoms of a blood clot including: sudden shortness of breath, swelling or pain in one leg

Tell your doctor immediately

Unexpected vaginal bleeding, changes in periods

Changes in vision

Tell your doctor

Hot flushing

Hair loss or thinning

Vaginal discharge

Tell your doctor if troublesome

Stomach upset

Take with food and tell your doctor if symptoms continue

If you notice any other effects, discuss them with your doctor or pharmacist.


This leaflet contains important, but not all, information about this medicine.

Prepared by the MyMedicines Committee at Christchurch Hospital, Te Whatu Ora - Waitaha, New Zealand. March 2023

For more general information about this sheet and its contents, see: What does a My Medicines sheet cover?

Web links for this sheet in different formats

Click on buttons to copy web addresses for this leaflet:

If your browser does not automatically copy these links use its copy command instead.

About My Medicines

My Medicines Patient Information Leaflets (PILs) contain important, but not all, information about the medicines they describe.

For more information about the sheets, see: What does a My Medicines sheet cover?

My Medicines is developed by a team at Te Whatu Ora – Waitaha. Our team is made up of doctors, pharmacists, and a non-medical person to help us keep to plain language. We also discuss our information with specialist health professionals or groups when needed