Medication Information Leaflet


What is this medication for?

Tamoxifen is used to treat breast cancer. It works by blocking the effect of estrogen, a hormone produced by your body.

How should I take/use this medication?

  • Take Tamoxifen once a day at around the same time each day.
  • You may take it with or without food.

What should I do if I forget to take/use this medication?

If you forget to take a dose, take it as soon as you remember. However, if it is too near to your next dose, skip the missed dose and take your next dose at the usual time. Do not take two doses to make up for the missed dose.

What precautions should I take?

Inform your healthcare professional if: 

  • You are allergic to this medication or any of the other ingredients of this medication
  • You are pregnant or planning to become pregnant
    • You should use effective birth control during treatment and for at least 2 months after stopping Tamoxifen
  • You are taking any other medications, including supplements, traditional medications and herbal remedies

What are some common side-effects of this medication?

  • Nausea may occur initially
    • If nausea occurs, take Tamoxifen after food.
  • Hot flushes
    • If this affects you, try taking Tamoxifen at bedtime.
    • If you are experiencing hot flushes, wearing light clothing, staying in a cool environment, and a cold cloth on your head may reduce these symptoms.
  • Leg swelling
    • Raising your legs on a foot stool or with a cushion or pillow may help to reduce the swelling.

What are some rare but serious side-effects that I need to seek medical advice immediately?

  • Signs of blood clots e.g. warmth, pain or redness with swelling on arm or leg
  • Sudden onset of cough, chest pain, shortness of breath or coughing out blood
  • Changes in eyesight
  • Unexpected bleeding or discharge from the vagina

The symptoms of a drug allergy include one or more of the following: 

  • Swollen face/eyes/lips/tongue
  • Difficulty in breathing
  • Itchy skin rashes over your whole body

If you experience any of these symptoms, you should stop your medication and see your healthcare professional immediately.

What food or medication should I avoid when I take this medication?

Avoid taking grapefruit when you are taking this medication as grapefruit may interact with Tamoxifen.

How should I store this medication?

Store in a cool and dry place, away from direct sunlight. Keep this medication away from children. 

How should I throw away this medication safely?

Pack Tamoxifen into a black trash bag and seal it tightly before throwing it into the rubbish chute or bin. 


If you take more than the recommended dose, please seek medical advice immediately. The information provided on this page does not replace information from your healthcare professional. Please consult your healthcare professional for more information.

This article is jointly developed by members of the National Medication Information workgroup. The workgroup consists of cluster partners (National Healthcare Group, National University Health System and SingHealth), community pharmacies (Guardian, Unity and Watsons) and Pharmaceutical Society of Singapore. The content does not reflect drug availability and supply information in pharmacies and healthcare institutions. You are advised to check with the respective institutions for such information.

Last updated on Jan 2022


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