Tamoxifen belongs to a class of medications called anti-oestrogen. It works by blocking the action of oestrogen hormone within the body. It is used to treat breast cancer and infertility in women caused by ovulation problems (the process of egg production and release). It is also used to prevent breast cancer in high risk individuals and to prevent gynaecomastia (abnormal enlargement of male breast) in men receiving long-term Bicalutamide treatment. Doctors may sometimes prescribe Tamoxifen for other conditions related to oestrogen levels in the body.
Tamoxifen is available as a tablet which is taken by mouth. You may take Tamoxifen with or without food.
Treatment of breast cancer
20 mg daily.
Prevention of breast cancer in women at high risk
20 mg daily for 5 years.
Initially 20 mg daily on days 2, 3, 4 and 5 of the menstrual cycle. If necessary, increase to 40 mg then 80 mg daily in subsequent menstrual cycles. If menstrual cycles are irregular, start the initial course on any day, with subsequent courses starting 45 days later, or on day 2 of the next cycle if menstruation occurs.
20 mg once weekly.
Common dosing schedule:
This schedule is for reference only, adjustments may be made according to individual needs.
Some common medications Tamoxifen may interact with:
Tamoxifen may interact with many other medications. Please notify your doctor or pharmacist if you are taking the above medication, dosage adjustments might be needed.
In Hong Kong, Tamoxifen is a prescription only medicine, and requires a prescription from a doctor to be purchased in a pharmacy. It can also be obtained from doctors. To find a pharmacy near you, refer to the list of pharmacies (“Authorized Sellers of Poisons”) from the Hong Kong Department of Health.
For more information about drug names and ingredients, you can visit Hong Kong’s Drug Office at https://www.drugoffice.gov.hk
Need more information?
For detailed information about the use of Tamoxifen in children, pregnancy and breastfeeding, and for questions about drug interactions, please check with your pharmacist or doctor.
Disclaimer: our goal is to provide you with the most relevant drug information and common dosage for Hong Kong. This information does not constitute medical advice. For specific treatment recommendations and advice, always discuss with your doctor or pharmacist, and follow the instructions included with your specific medicine.