Tamoxen is an anti-estrogens. It is used in the treatment of breast cancer. It is also used to reduce the risk of breast cancer in women with a high chance of developing it. This medicine helps to slow down the growth and multiplication of cancer cells. Tamoxen is also helpful in the treatment of infertility. It can be taken with or without food, but take it at the same time to get the most benefit. It should be taken as your doctor's advice. The dose and how often you take it depends on what you are taking it for. Your doctor will decide how much you need to improve your symptoms. Swallow the tablets whole with a drink of water. You should take this medicine for as long as it is prescribed for you. The most common side effects of this medicine include nausea, skin rash, hot flushes, thinning of hair and tiredness. If these bother you or appear serious, let your doctor know. There may be ways of reducing or preventing them. Some side effects may mean you should inform your doctor immediately include vaginal bleeding, irregular menstrual period and vaginal discharge. It makes birth control pills less effective, hence use a condom and other preventive measures to avoid pregnancy. Before taking this medicine, tell your doctor if you are on treatment of infertility or had a blood clot disorder. Your doctor should also know about all other medicines you are taking as many of these may make this medicine less effective or change the way it works. Tell your doctor if you are pregnant or breastfeeding. Your doctor may perform some blood tests to check liver function and calcium level in the body.