Fluorouracil, which is also called 5FU, is a chemotherapy drug that is given as a treatment for many types of cancer, including head & neck, bowel, oesophagus, pancreatic and stomach cancer. This information describes 5FU, how it is given and some of its possible side effects.

What 5FU looks like

5FU is available as:

• a colourless fluid
• a cream (Efudix®) which is used to treat certain types of skin cancer.

How it is given

5FU may be given as:

• an injection into a vein (intravenously) through a fine tube (cannula) inserted into a vein, usually in the back of the hand or
• a drip (infusion) into a vein through a cannula;
• through a fine plastic tube inserted under the skin into a vein near the collarbone or
• into a fine tube inserted into a vein in the crook of your arm (PICC line) or
• a cream applied directly to the skin.

It can be given rapidly over a few minutes, or more slowly over 24 – 48 hours depending on the disease and type of chemotherapy being given with it.

Chemotherapy is usually given as a course of several sessions (or cycles) of treatment over a few months. The length of your treatment and the number of cycles you have will depend on the type of cancer for which you are being treated.

Possible side effects

Each person’s reaction to chemotherapy is different. Some people have very few side effects, while others may experience more. The side effects described in this information won’t affect everyone who is given 5FU, and may be different if you are having more than one chemotherapy drug. The side effects of 5FU as a cream are generally very mild.

We have outlined the most common side effects and some of the less common ones, so that you can be aware of them if they occur. However, we haven’t included those which are very rare and therefore extremely unlikely to affect you. If you notice any effects which you think may be due to the drug, but which are not listed in this information, please discuss them with your doctor, chemotherapy nurse or pharmacist.

Sore mouth and ulcers

Your mouth may become sore, or you may notice small ulcers during this treatment. Sucking ice chips whilst the chemotherapy is being given may help to reduce the chance of this occurring. Drinking plenty of fluids, and cleaning your teeth regularly and gently with a soft toothbrush, can also help. Tell your nurse or doctor if you have any of these problems, as special mouthwashes and medicines to prevent or clear any mouth infection can be prescribed.

Taste changes

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

Diarrhoea

This can usually be easily controlled with medicines such as imodium (loperamide) or codeine, but let your doctor know if it is severe or if it continues. It’s important to drink plenty of fluids if you have diarrhoea.

Gritty eyes and blurred vision

If this happens it is important that you tell your doctor, who 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.

Lowered resistance to infection

5FU can reduce the production of white blood cells by the bone marrow, making you more prone to infection. This effect can begin seven days after treatment has been given, and your resistance to infection usually reaches its lowest point 10–14 days after chemotherapy. Your blood cells will then increase steadily, and will usually have returned to normal levels within 21 days.

Contact your doctor or the hospital straight away if:

• your temperature goes above 38ºC (100.5ºF)
• you suddenly feel unwell (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 the number of blood cells (the blood count) is still low.

Bruising or bleeding

5FU 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, or bleeding gums.

Anaemia (low number of red blood cells)

While having treatment with 5FU you may become anaemic. This may make you feel pale, tired and breathless on exertion. Let your doctor or nurse know if these effects are a problem.

Tiredness feeling weak

You may feel very tired. It’s important to allow yourself plenty of time to rest.

Less common side effects

Feeling sick (nausea) and being sick (vomiting)

If you feel sick this may begin after the treatment is given and last for a few days. Your doctor can prescribe very effective anti-sickness (anti-emetic) drugs to prevent, or greatly reduce, nausea. If the sickness isn’t controlled, or continues, tell your doctor; they can prescribe other anti-sickness drugs which may be more effective.

Hair loss

This is rare, but your hair may thin, or occasionally fall out completely. If hair loss happens, it usually begins about 3–4 weeks after starting treatment, although it may occur earlier. Hair loss is temporary, and the hair will regrow once the treatment ends. Your nurse can give you advice about 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 5FU, 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, protective clothing and a hat.

Rashes

5FU 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

This is sometimes known as palmar plantar or hand and foot syndrome. This can happen when 5FU 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 may help to reduce this. Moisturising creams such as E45 or Aqueous Cream can also help greatly.

Increased production of tears

This is sometimes be caused by 5FU. It is a temporary side effect, although the tears can sometimes irritate the front of the eye (conjunctiva). If this happens your doctor can give you soothing eye drops.

Additional information

Risk of blood clots

Cancer can increase your risk of developing a blood clot (thrombosis), and having chemotherapy may increase this risk further. A blood clot may cause symptoms such as pain, redness and swelling in a leg, or breathlessness and chest pain. Blood clots can be very serious so it is important to tell your doctor straightaway if you have any of these symptoms. However, most clots can usually be successfully treated with drugs to thin the blood.

Other medicines

Some medicines (including those you can buy in a shop or chemist) can be harmful to take when you are having chemotherapy. Let your doctor know about any medications you are taking, including non-prescribed drugs such as complementary therapies and herbal drugs.

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 5FU, as the developing foetus may be harmed. It is important to use effective contraception while taking this drug, and for at least a few months afterwards.