• Tamoxifen is a drug commonly used as part of the treatment for some breast cancers. 
  • It belongs to a group of drugs known as hormone therapies and is also described as an anti-oestrogen drug. 

Why have I been prescribed Tamoxifen?

  • Tamoxifen is a drug commonly used as part of the treatment for some breast cancers
  • It belongs to a group of drugs known as hormone therapies and is also described as an anti-oestrogen drug. 
  • You will usually take Tamoxifen for five years although some people may be on it for longer.

How does it work?

The female hormones oestrogen and progesterone can affect the growth of breast cancer cells. Some breast cancers are stimulated by the hormone oestrogen, which encourages cells to grow. These cancers are known as oestrogen receptor positive tumours. Tamoxifen works by blocking the effects of oestrogen on cancer cells, so stopping them from growing. This is why it is called an anti-oestrogen.

When and how do I take it?

Tamoxifen is available as a tablet and a liquid. It doesn’t matter what time of the day it is taken and it can be taken with or without food.

What’s the dose?

The recommended dose is 20mg once a day.

Could they interact with other tablets?

  • It is not advisable to take anticoagulants (drugs that thin the blood) such as Warfarin while you are on Tamoxifen. 
  • Always check with your specialist if you are concerned about taking any other medicines.
  • It is important to use a non-hormonal form of contraception while taking Tamoxifen Tablets.

Herbal supplements should be used with caution and only after informing your doctor first.

What are the possible risks or side-effects?

The most common side effects are similar to menopausal symptoms, such as:

  • hot flushes
  • night sweats
  • vaginal dryness or discharge
  • irregular periods
  • lighter periods or stoppage of periods

These symptoms are more common in women taking Tamoxifen before the menopause than after.

Other possible side effects include: 

  • headaches
  • vaginal irritation or discharge
  • leg cramps at night

A small number of women notice an increase in downy facial hair or changes to their singing voice.

Some women may have indigestion or mild nausea, although these symptoms usually improve with time. Many women find that they put on weight during their treatment, although there is no clear evidence linking this weight gain to Tamoxifen.

Tamoxifen can also affect the lining of the womb (endometrium), which may become thickened. In a very few cases it may cause polyps or ovarian cysts or, very rarely, cancer of the womb. If you have any unexpected side effects contact your GP or specialist. Some studies have shown a slightly higher increase in blood clotting in women taking Tamoxifen. This may be a higher risk in women having chemotherapy drug treatment at the same time.

There is a very slight increased risk in changes in vision in women taking Tamoxifen. The risk is greater in women who have problems such as cataracts before they start to take Tamoxifen. A very rare side effect of Tamoxifen is hair loss.

Can I drink alcohol while taking it?

  • Tamoxifen may cause dizziness
  • These effects may be worse if you take it with alcohol.

What if I’m pregnant/breastfeeding?

Tamoxifen cannot be given during pregnancy. The drug is not recommended during lactation.

If you have any more questions please ask your Pharmacist.

Remember to keep all medicines out of reach of children
Please Note:
 We have made every effort to ensure that the content of this information sheet is correct at time of publish, but remember that information about drugs may change. This sheet does not list all the uses and side-effects associated with this drug. For full details please see the drug information leaflet which comes with your medicine. Your doctor will assess your medical circumstances and draw your attention to any information or side-effects which may be relevant in your particular case.








Health Reference: Cancer