Chemotherapy drugs are given by injection into a vein (intravenously) or as tablets. Chemotherapy into the vein is given as a session of treatment, usually over a few hours. This is followed by a rest period of a few weeks, which allows your body to recover from any side effects of the treatment.

There are many different chemotherapy drugs, and combinations of drugs, used to treat breast cancer. You may be offered a choice of chemotherapy treatments, as the different combinations have different side effects. Research is always being carried out to improve the effectiveness of chemotherapy whilst reducing the side effects, and you may be asked to take part in research trials comparing different types of chemotherapy.

Chemotherapy is usually given to you as an outpatient. A complete course of chemotherapy is likely to take 4–6 months.

In women whose cancer is very unlikely to come back, chemotherapy may only reduce the chance of recurrence by a small amount. In women whose chance of the cancer coming back is higher, chemotherapy may greatly reduce the chance of recurrence. Your doctor can let you know how likely chemotherapy is to make a difference in your case. They can also let you know about the possible side effects.

Chemotherapy drugs can cause side effects, but these can usually be well controlled with medicines.

Lowered resistance to infection Chemotherapy can reduce the production of white blood cells by the bone marrow, making you more prone to infection. Contact your doctor or the hospital straightaway if:

• Your temperature goes above 38ºC (100.5ºF).
• You suddenly feel ill (even with a normal temperature).

You will have a blood test before having more chemotherapy, to make sure that your cells have recovered. Occasionally it may be necessary to delay your treatment if your blood count is still low.

Bruising or bleeding Chemotherapy can reduce the production of platelets, which help the blood to clot. Let your doctor know if you have any unexplained bruising or bleeding, such as nosebleeds, blood spots or rashes on the skin, and bleeding gums.

Low number of red blood cells (anaemia) You may become anaemic. This may make you feel tired and breathless.

Nausea and vomiting Some chemotherapy drugs can make you feel sick or even be sick. This can be helped by taking anti-sickness drugs (anti-emetics), which your doctor can prescribe.

Sore mouth Some chemotherapy drugs can make your mouth sore and may cause small ulcers. Regular mouthwashes are important and the nurses will show you how to do these properly.

Poor appetite If you don't feel like eating during treatment, you could try replacing some meals with nutritious drinks or a soft diet. Our section on diet and cancer has some useful tips on coping with eating problems.

Hair loss Some chemotherapy drugs may make your hair fall out. This can be very upsetting. However, if your hair does fall out, there are many ways of covering up, including wigs, hats or scarves. You may be entitled to a free wig from the National Health Service. Your doctor, or the nurse looking after you, will be able to arrange for a wig specialist to visit you. If your hair falls out, it should start to grow back within about 3–6 months of the end of treatment.

Chemotherapy affects people in different ways. Some people find they are able to lead a fairly normal life during their treatment, but many people become very tired and have to take things much more slowly. Just do as much as you feel like and try not to overdo it.

Although they may be hard to deal with at the time, these side effects will gradually disappear once your treatment is over.

Early menopause Chemotherapy may make some women have an early menopause.

Contraception It is not advisable to become pregnant while taking any of the chemotherapy drugs used to treat breast cancer, as they may harm the developing foetus. It is important to use effective contraception during your treatment and for a year afterwards. You can discuss this with your doctor or specialist nurse.

Condoms should be used during sex within the first 48 hours after chemotherapy, to protect your partner from any of the drug that may be present in vaginal fluid.

Our section on chemotherapy discusses the treatment and its side effects in more detail. This section also includes information about individual drugs you may have as part of your treatment, and their particular side effects.