Goserelin (Zoladex) for breast cancer | Cancer Research UK
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Goserelin (Zoladex) for breast cancer

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Goserelin is a hormone therapy drug used to treat breast cancer and prostate cancer. This page tells you about its use for breast cancer and the possible side effects. There are sections about


What goserelin is

Goserelin is also known by its brand name Zoladex and is a type of hormone therapy. It is a luteinising hormone (LH) blocker. This means that it stops the release of luteinising hormone from the pituitary gland. In women, this stops the ovaries from producing oestrogen. In men, it stops the testicles producing testosterone.

Goserelin is a treatment for women who have breast cancer that has oestrogen receptors (ER positive) and who have not yet reached the menopause.


How you have goserelin

You have goserelin as an injection just under the skin of your tummy (abdomen) every 28 days. It is called a depot injection, which means that the drug is absorbed slowly into your body over the 28 days.

We've listed the side effects associated with goserelin below. You can use the links to find out more about each side effect. Where there is no link, please go to the cancer drug side effects section or use the search box at the top of the page.


Common side effects

Most women have menopausal symptoms, including the following side effects. More than 10 in every 100 women have one or more of these

  • Periods stopping while you are on treatment – they usually start again within 6 to 12 months of your treatment finishing. But if you are close to the age of your natural menopause, they may not come back
  • Hot flushes and sweats affect more than 9 out of 10 women (90%)
  • Lowered interest in sex (libido)

Other common side effects include

  • Headaches
  • Skin rashes – these are usually mild but let your doctor know if you have a rash
  • Bruising of the skin where you have the injection

Occasional side effects

Between 1 and 10 in every 100 women have one or more of these.

  • Vaginal bleeding – when you first start the treatment you may have vaginal bleeding as if you were having a period. It usually lasts from a few days to a month and doesn’t happen again
  • Feeling or being sick is usually mild and can be controlled by anti sickness medicines
  • Vaginal dryness is caused by the reduced amount of oestrogen
  • Weight gain – you may find that you put on weight easily. You should be able to control this with diet and exercise, but it is sometimes a struggle to keep weight down when you are having hormone treatment
  • Mood changes, including depression
  • Bone thinning is caused by low oestrogen levels over a long period of time. When your bones are less dense they may break more easily. You will have a DEXA scan to check your bone density before you start treatment. Research has shown that bone density can improve once treatment with goserelin has finished
  • Changes in blood pressure – it may be lower or higher than usual. Your nurse or doctor will check it regularly. Most women can carry on taking goserelin and their blood pressure goes back to normal either during treatment or when the treatment ends
  • Tingling in your fingers or toes
  • Hair thinning
  • Pain in your joints – let your doctor or nurse know if you have this
  • Tumour flare – any symptoms caused by your breast cancer may get worse for the first couple of weeks after the first injection. This is because there is a temporary brief increase in the amount of oestrogen in the body

Rare side effects

Fewer than 1 in 100 women have these effects.

  • An allergic reaction to goserelin causing sudden itching or a skin rash, swelling of the face, lips or tongue, or wheezing or breathlessness – tell your doctor or nurse straight away if you have this
  • High blood calcium levels when starting the treatment – let your doctor or nurse know if you feel thirsty, lose your appetite, or are very tired, weak and confused

Important things to remember

You may have a few of these side effects. They 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

Coping with side effects

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

Other medicines

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

Pregnancy and contraception

This drug may harm a baby developing in the womb. Let your doctor or nurse know before you start treatment if there is any possibility that you may be pregnant. It is important not to become pregnant while you are having treatment and for a few months afterwards. Goserelin is not a contraceptive and, even if your periods have stopped, you could become pregnant while you are having treatment. 

It is important to use reliable contraception, such as the condom or cap (diaphragm), throughout the treatment. Don't take the pill (oral contraceptive). Discuss this with your doctor or specialist nurse.Talk to your doctor or nurse about effective contraception before starting treatment.


Do not breastfeed during this treatment because the drug may come through in the breast milk.


More information about goserelin

This information does not list all the very rare side effects of this treatment that are very unlikely to affect you. For further information look at the Electronic Medicines Compendium website at www.medicines.org.uk.

If you have a side effect not mentioned here that you think may be due to this treatment you can report it to the Medicines Health and Regulatory Authority (MHRA) at www.mhra.gov.uk.


Related information

We have specific information about hormone therapy for breast cancer.

You can also read about coping with hot flushes and sweats.

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Updated: 4 February 2015