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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.

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?

Some medicines available without a prescription may react with tamoxifen including:

  • fluconazole (e.g. Diflucan®) or miconazole (e.g. Daktarin Oral Gel®)

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 persist

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

Other information:

  • 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.

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

Prepared by the PILs Committee at Christchurch Hospital, Canterbury District Health Board, New Zealand. October 2018

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

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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 the Canterbury District Health Board. 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