Fulvestrant for breast cancer (Faslodex)

Fulvestrant injection will be given to you by your doctor or nurse. Try to keep your appointments so that you get the injections on time.

The most common side-effects are feeling tired, feeling sick, and pain at the site of the injection.

Type of medicineAn anti-oestrogen hormone antagonist
Used forBreast cancer
Also calledFaslodex®
Available asInjection

Fulvestrant is known as a hormonal breast cancer treatment. It is used to treat advanced breast cancer and metastatic breast cancer. Advanced breast cancer is cancer which has progressed despite treatment, and metastatic breast cancer is cancer which has spread into other parts of the body.

Many breast cancers need the female hormone oestrogen to grow. The cells of these cancers have tiny areas called receptors on their surface, which oestrogen can attach to. They are called 'hormone receptor-positive' cancers. Fulvestrant works by blocking the receptors and this prevents oestrogen from reaching the cancer cells. This slows the growth of the cancer.

Some medicines are not suitable for people with certain conditions, and sometimes a medicine may only be used if extra care is taken. For these reasons, before you start having fulvestrant injections it is important that your doctor or nurse knows:

  • If you have not yet gone through the menopause, or if there is a possibility you might be pregnant.
  • If you have problems with the way your liver works, or the way your kidneys work.
  • If you have any blood clotting problems or bleeding disorders.
  • If you have ever had an allergic reaction to a medicine.
  • If you are taking any other medicines. This includes any medicines you are taking which are available to buy without a prescription, such as herbal and complementary medicines.
  • Before you start this treatment, read the manufacturer's printed information leaflet from inside your pack. The manufacturer's leaflet will give you more information about fulvestrant and a full list of the side-effects which you may experience from having it.
  • Your doctor or nurse will give you the fulvestrant injection. He or she will give you an injection every two weeks to begin with (for the first three doses); after that it will be given once each month. It will be injected slowly over a couple of minutes into muscles in your bottom. For each dose, you will be given an injection into both buttocks.
  • Try to keep your regular appointments with your doctor or clinic. This is so your doctor can check on your progress. You may need to have a blood test from time to time.
  • Fulvestrant injection contains a small amount of alcohol. This is usually harmless, but if you have ever had a problem with an addiction to alcohol, you should let your doctor know about this.
  • If you are having an operation, tell the person carrying out the treatment that you are having fulvestrant treatment.
  • If you buy any medicines, check with a pharmacist that they are suitable to take with your other medicines.

Along with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. The table below contains some of the most common ones associated with fulvestrant. You will find a full list in the manufacturer's information leaflet supplied with your medicine. The unwanted effects often improve as your body adjusts to the new medicine, but speak with your doctor or pharmacist if any of the following continue or become troublesome.

Common fulvestrant side-effects
What can I do if I experience this?
Headache, back painAsk your doctor or pharmacist to recommend a suitable painkiller
Feeling weak or tiredDo not drive or use tools or machines until you feel better
Hot flushesTry to keep cool by wearing light, airy clothes
Feeling or being sickStick to simple meals - avoid rich or spicy foods
DiarrhoeaDrink plenty of water to replace any lost fluids
Pain or inflammation at the injection site, loss of appetite, urine infectionsSpeak with your doctor about these
Changes to liver enzymesYour doctor will arrange for you to have blood tests to check for this

Important: your doctor will discuss with you the possibility of more serious side-effects. These are listed below. You must let your doctor know straightaway if any happen to you:

  • Any pain or swelling in your lower leg. This is because taking fulvestrant can increase the risk of you developing a blood clot in your legs.
  • Any swelling of your face or throat, feeling breathless, or a severe rash. These may be signs of an allergic-type reaction.

If you experience any other symptoms which you think may be due to this medicine, speak with your doctor or pharmacist.

  • If you are asked to store fulvestrant injection, keep it in a refrigerator at 2-8°C.
  • Keep all medicines out of the reach and sight of children.

If you buy any medicines, check with a pharmacist that they are suitable to take with your other medicines.

If you are having an operation or any dental treatment, tell the person carrying out the treatment which medicines you are taking.

This medicine is for you. Never give it to other people even if their condition appears to be the same as yours.

Do not keep out-of-date or unwanted medicines. Take them to your local pharmacy which will dispose of them for you.

If you have any questions about this medicine ask your pharmacist.

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Further reading & references

Original Author:
Helen Allen
Current Version:
Helen Allen
Peer Reviewer:
Dr Helen Huins
Document ID:
3883 (v25)
Last Checked:
19 November 2013
Next Review:
18 November 2016
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The information on this page is written and peer reviewed by qualified clinicians.

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.