Fluorouracil (5FU)

Introduction

Fluorouracil (5FU) is chemotherapy that is given as a treatment for some types of cancer including bowel, breast, stomach, and gullet cancer. This section describes fluorouracil, how it is given and some of its possible side effects. It should ideally be read with CancerBACUP's information on chemotherapy, which gives more information and advice.

Each person's reaction to chemotherapy is unique. Some people have very few side effects, while others may experience more. The side effects described in this section will not affect everyone who is given fluorouracil, and may be different if you are having more than one chemotherapy drug.

We have outlined the commonest and the less common side effects, so that you can be aware of them if they occur. However, we have not included those which are very rare and therefore extremely unlikely to affect you. If you do notice any effects which you think may be due to the drug, but which are not listed here, please discuss these with your doctor or chemotherapy nurse.

You will see your doctor regularly while you have this treatment so that they can monitor the effects of the chemotherapy. This section should help you to discuss any queries about your treatment and its side effects with your doctor or chemotherapy nurse.

What it looks like

Fluorouracil is available as:

• A clear fluid

• A cream (Efudix)

• Capsules of a drug called Uftoral are available, which is similar to 5FU. CancerBACUP has further information on Uftoral. The side effects of Uftoral may be different to those mentioned here.

How it is given

• By injection into the vein (intravenously) through a cannula (a fine tube inserted into the vein.

• As an infusion (drip) into the vein through a cannula. It may be given through a central line, which is inserted under the skin into a vein near the collarbone. CancerBACUP's section on central lines has further information.

• As cream (Efudix) applied directly to the skin.

Possible side effects

Sore mouth and taste change.  Your mouth may become sore, or you may notice small ulcers during this treatment. Drinking plenty of fluids and cleaning your teeth regularly and gently with a soft toothbrush can help to reduce the risk of this happening. Tell your doctor if you do have any of these problems as they can prescribe special mouthwashes and medicine to prevent or clear any mouth infection.

You may notice that your food tastes different. Normal taste will come back after the treatment finishes.

Diarrhoea. This can usually be easily controlled with medicine but let your doctor know if it is severe or continues. It is important to drink plenty of fluids if you do have diarrhoea.

Gritty eyes and blurred vision. If this happens it is important that you tell your doctor. They can prescribe soothing eye drops.

Skin changes. Your skin may darken, due to excess production of pigment. This will slowly return to normal a few months after the treatment has finished. The skin over the vein used for the injection may become discoloured, but this is only temporary.

Temporary reduction in the production of blood cells by the bone marrow. This can result in anaemia, risk of bruising or bleeding and infection. The number of blood cells in your blood may begin to reduce from about seven days after the treatment has been given and usually reaches its lowest point at 10-14 days after chemotherapy. Your blood cells will then increase steadily and will have usually returned to normal within 21 days.

The extent to which your blood cells are reduced depends on the dose of 5FU you receive and which other chemotherapy drugs, if any, are given in combination. Your doctor can advise you how likely it is that your blood cells will be lowered by the chemotherapy. Your blood will be checked regularly to see how well your bone marrow is working.

If your temperature goes above 38°C (100.5°F), or you develop any unexplained bruising or bleeding, or you suddenly feel unwell, even if you have a normal temperature, contact your doctor or the hospital straight away.

Tiredness and a general feeling of weakness. It is important to allow yourself plenty of time to rest. CancerBACUP has further information on coping with fatigue.

Less common side effects

Nausea (feeling sick) and vomiting. There are now very effective anti-sickness drugs to prevent or greatly reduce nausea and vomiting. If it does happen it may begin after the treatment is given and last for a few days. If the sickness is not controlled, or continues, tell your doctor. They can prescribe other anti-sickness drugs that may be more effective. CancerBACUP's section on managing nausea and vomiting has further information.

Hair loss. Hair loss is uncommon but hair may thin, or occasionally be lost completely. If hair loss happens, it usually begins about 3-4 weeks after starting treatment, although it may occur earlier. It is temporary, and the hair will regrow once the treatment is finished. CancerBACUP has further information on coping with hair loss.

Changes to nails. Your nails may become brittle, chipped and ridged. These changes grow out slowly over a few months once the treatment has ended.

Sensitivity of the skin to sunlight. During treatment with fluorouracil, and for several months afterwards, you will be more sensitive to the sun, and your skin may burn more easily than normal. You can still go out in the sun, but always wear a high protection factor suncream and protective clothing. You may also wish to read CancerBACUP's information on skin protection.

Rashes. Fluorouracil can cause a rash, which may be itchy. Your doctor can prescribe treatment to help reduce this.

Soreness and redness of the palms of the hands and soles of the feet (sometimes known as palmar planter or hand and foot syndrome). This can happen when fluorouracil is given continuously or over a long time. It is temporary and improves when the treatment is finished. You may be prescribed vitamin B6 (pyridoxine), which can help to reduce this.

Increased production of tears may sometimes be caused by fluorouracil. This is temporary.

Additional information

Some other medicines can be harmful to take when you are having chemotherapy. Always tell your doctor about any other medicine you are taking.

Fertility. Your ability to become pregnant or father a child may be affected by taking this drug. It is important to discuss fertility with your doctor before starting treatment.

Contraception. It is not advisable to become pregnant or father a child while taking fluorouracil as it may harm the developing foetus. It is important to use effective contraception whilst taking this drug, and for at least a few months afterwards. Again, discuss this with your doctor.