Tamoxifen

Tamoxifen is an anti-oestrogen drug given to pre-menopausal and post-menopausal women and men with primary breast cancer. It can also be given to people with local or regional recurrence or secondary breast cancer.

Common side effects

• Hot flushes.
• Night sweats.
• Vaginal dryness or irritation.
• Loss of sex drive.

If you are experiencing any of these menopausal-like side effects then you may find it helpful to read our factsheet on managing menopausal symptoms.

• Indigestion or mild nausea (this will usually improve with time).
• Periods become irregular or lighter.
• Periods may stop while taking tamoxifen, often because the menopause had occurred naturally or other treatments such as chemotherapy have caused an earlier menopause.
• If you are post-menopausal there is evidence that tamoxifen slows down the process of bone loss, reducing the risk of osteoporosis (thinning of the bone). Pre-menopausal women however, may experience thinning of the bones.

If you have concerns about any of the side effects listed above, you may wish to discuss them with your specialist or GP.

Less common side effects

• Eye-sight problems.
• Hair thinning.
• Increased risk of developing blood clots (but still very low overall). Because of the risk of blood clots, it is important to tell your GP if you have any symptoms such as a swelling or pain in your leg or a feeling of shortness of breath.
• Thickening of the lining of the womb.
• Polyps, ovarian cysts or, very rarely, cancer of the womb.

It's important to tell your GP or specialist if you have any unexpected vaginal bleeding, discharge or pain.