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Tamoxifen Print


Generic name:
Trade name: Saltamox
Other names:

Drug type: Tamoxifen is also called by its brand name Saltamox. It is a hormone treatment developed over thirty years ago to treat breast cancer. Tamoxifen prevents oestrogen from going into breast cancer cells. Oestrogen can stimulate some breast cancer cells to divide and grow. Tamoxifen lowers the risk of breast cancer coming back (recurring) or developing in the other breast. It is occasionally used to treat other types of cancer, but the information here refers to its use for breast cancer.

Many breast cancers are stimulated to grow by the female sex hormones oestrogen and progesterone. These breast cancers are ‘hormone sensitive’ or ‘hormone receptor positive’ and can be treated with drugs that block the effects of these hormones.

Tamoxifen is usually prescribed for women who are ER positive. That means, that oestrogen receptors (ER) have been found on their breast cancer cells. The oestrogen receptor is the part of the breast cancer cell that oestrogen locks on to, stimulating the cell to multiply. Tamoxifen is able to lock on to the oestrogen receptor and stop the oestrogen from getting to the cancer cell.

To find out if your cancer has hormone receptors, your specialist will arrange tests on your breast cancer cells. Your specialist may also prescribe tamoxifen if your cancer cells are ER negative, but have progesterone receptors (are PR positive). Unlike some types of hormone treatment, women can have treatment with tamoxifen both before and after the menopause.

How you have treatment

Tamoxifen comes as a tablet or liquid that you swallow. You take it daily. You may find it easiest to take it at the same time every day.

Common side effects

Many people will have one or more of the following side effects

  • Hot flushes and sweats – around 45% of women have moderate to severe hot flushes and sweats while taking tamoxifen
  • Changes to your periods – if you haven’t had your menopause your periods may become irregular. Some women find their periods stop. They usually start again within 6 to12 months of treatment finishing. However, for some women close to the time of their natural menopause they don’t start again
  • Fatigue or tiredness affects about 1 out of 4 women
  • Painful joints happen in about 1 out of 4 (25%) women
  • Tamoxifen may have a harmful effect on a developing baby and before you start treatment you should let your doctor or nurse know if there is any possibility that you may be pregnant
  • Tamoxifen is not a contraceptive and even if your periods have stopped, you could become pregnant while you are on treatment – discuss contraception with your doctor before you start your treatment
  • Feeling or being sick affects about 1 out of 5 women (20%) – it usually happens at the start of treatment and goes after a few days or weeks, but tends to be mild and easily controlled by anti sickness tablets

Occasional side effects

Some people will have one or more of the following effects

  • Discharge from the vagina, dryness and itching affect about 1 in 10 women – tell your doctor or nurse if you have any of these side effects
  • Fluid retention may cause ankle and or finger swelling (or weight gain) in about one in 10 people
  • Weight gain – fewer than 1 in 10 people (10%) put on weight while they are taking tamoxifen.
  • Headaches
  • Low mood or depression – about 1 in 10 people (10%) treated have some change in their mood. Let your doctor or nurse know if you feel low or depressed.
  • Hair thinning is usually only slight and not noticeable

Rare side effects

A few people may have the following effects

  • Tumour flare – if you have cancer that has spread to your bones, you may have some increased pain when you first start taking tamoxifen. This is called ‘tumour flare’. Very rarely it makes you feel sick, thirsty or constipated. These symptoms can be signs that the level of calcium in your blood has gone up. If you have any of these symptoms, tell your doctor or nurse.
  • Your risk of blood clots (thrombosis) can slightly increase when you take tamoxifen. If you or a close relative have had a blood clot in the past tell your doctor. They may want to change you to a different type of hormone therapy
  • Liver changes that are very mild and unlikely to cause symptoms – the liver will almost certainly go back to normal when treatment is finished, but you will have regular blood tests to check how well your liver is working
  • Eye problems can very occasionally occur – if you notice any changes in your eyesight tell your doctor
  • A skin rash
  • Womb cancer – there is a very slight increase risk of developing a cancer of the womb. If you have any abnormal bleeding, or other symptoms that concern you, tell your doctor so you can have a check up.

Tamoxifen can react with the drug warfarin. If you are taking warfarin you will need to have regular blood tests, and your dose of warfarin may need to be adjusted.

Important things to remember

The side effects above may be mild or more severe. A side effect may get better or worse through your course of treatment, or more side effects may develop as the course goes on. This depends on

  • How many times you've had the drug before
  • Your general health
  • The amount of the drug you have (the dose)
  • Other drugs you are having

Some side effects are inconvenient or upsetting but not damaging to your health.

Some side effects are serious medical conditions and need treating. Where we have urged you to contact your doctor, this is because

  • Your side effect may need treating
  • Your drug dose may need reducing to try to prevent the side effect

Tell your doctor about any other medicines you are taking, including vitamins, herbal supplements and other over the counter remedies – some drugs can react together.

Talk to your doctor, pharmacist or nurse about all your side effects so that they can help you manage them. You should have a contact number for your chemotherapy nurse, clinic or ward nurse. You can ring if you have any questions or problems. They can give you advice or reassure you. If in doubt, call them.

Last Updated on Thursday, 21 January 2010 09:59