Chemotherapy for colon and rectal cancer

Chemotherapy uses anti-cancer (cytotoxic) drugs to destroy cancer cells.

These drugs disrupt the way cancer cells grow and divide, but they also affect normal cells.

Chemotherapy may be given:

  • after surgery, to reduce the risk of cancer coming back
  • before surgery, to shrink the cancer and reduce the risk of it coming back
  • as the main treatment, if the cancer has spread to parts of the body such as the liver or lungs
  • with radiotherapy to treat rectal cancer. This is called chemoradiation.

The drugs most commonly used to treat colon cancer or rectal cancer are:

Often, two or more chemotherapy drugs are given in combination. The three most commonly used combinations are:

  • FOLFOX (folinic acid, fluorouracil and oxaliplatin)
  • FOLFIRI (folinic acid, fluorouracil and irinotecan)
  • CAPOX (XELOX) (capecitabine and oxaliplatin).

Chemotherapy for small bowel cancer

The drugs most commonly used to treat small bowel cancer are:

Chemotherapy is not suitable for everyone. Doctors are still researching how effective it is at treating small bowel cancer.

How chemotherapy is given

You usually have chemotherapy as an outpatient. It can be given into a vein or taken by mouth as a tablet. Chemotherapy given into a vein (intravenous) goes directly into your blood and is carried to all areas of your body.

We have more information about how chemotherapy is given.

Getting support

Macmillan is here to support you. If you would like to talk, you can:

Side effects of chemotherapy

Chemotherapy drugs may cause unpleasant side effects, but these can usually be well controlled with medicines and will usually go away once treatment has finished. Not all drugs cause the same side effects and some people may have very few.

You can talk to your doctor or nurse about what to expect from the treatment that’s planned for you. The main side effects are described here as well as some ways to reduce or control them.

Risk of infection

This treatment can reduce the number of white blood cells in your blood. These cells fight infection. If the number of white blood cells is low, you are more likely to get an infection. A low white blood cell count is called neutropenia.

If you have an infection, it is important to treat it as soon as possible. Contact the hospital straight away on the 24-hour contact number you have if:

  • your temperature goes over 37.5°C (99.5F)
  • you suddenly feel unwell, even with a normal temperature
  • you have symptoms of an infection.

Symptoms of an infection include:

  • feeling shivery
  • a sore throat
  • a cough
  • diarrhoea
  • needing to pass urine often.

It is important to follow any specific advice your cancer treatment team gives you.

The number of white blood cells will usually return to normal before your next treatment. You will have a blood test before having more treatment. If your white blood cell count is low, your doctor may delay your treatment for a short time.

Bruising and bleeding

This treatment can reduce the number of platelets in your blood. Platelets are cells that help the blood to clot. Tell your doctor if you have any bruising or bleeding that you cannot explain. This includes:

  • nosebleeds
  • bleeding gums
  • tiny red or purple spots on the skin that may look like a rash.

Some people may need a drip to give them extra platelets. This is called a platelet transfusion.

Anaemia (reduced number of red blood cells)

Chemotherapy can reduce the number of red blood cells in your blood. These cells carry oxygen around the body.

If the number of red blood cells is low, you may be tired and breathless. Tell your doctor or nurse if you feel like this. If you are very anaemic, you may need a drip to give you extra red blood cells. This is called a blood transfusion.


Some chemotherapy drugs can cause diarrhoea. Diarrhoea means passing more stools (poo) than is usual for you or having watery or loose stools. If you have a stoma, it will be more active than usual.

You may have diarrhoea in the first few days of treatment. But it usually happens between treatment cycles. If you have this side effect, tell your nurse or doctor as they can give you medicine to help. If you still have diarrhoea after 24 hours, contact the hospital on the telephone numbers you have been given and speak to a doctor or nurse.

If you have a stoma, your stoma care nurse can also give you advice and support.

Make sure you drink at least 2 litres (3½ pints) of fluid each day to replace the fluid you are losing. Eat less fibre, such as cereals, raw fruits and vegetables, until the diarrhoea improves.

Sometimes diarrhoea is more severe. If you have diarrhoea more than 4 times in a day or at night, it is important to contact the hospital straight away and speak to a doctor or nurse.

If you are taking capecitabine and your diarrhoea does not get better, tell your doctor or nurse. Sometimes you may have to stop taking capecitabine until the diarrhoea gets better.

You may need to go to hospital to have fluids through a drip (infusion), or you may need antibiotics.

Feeling sick

You may feel sick in the first few days after this treatment. Your doctor will give you anti-sickness drugs to help prevent or control sickness. Take the drugs exactly as your nurse or pharmacist tells you. It is easier to prevent sickness than to treat it after it has started.

If you feel sick, take small sips of fluids and eat small amounts often. If you continue to feel sick, or if you vomit more than once in 24 hours, contact the hospital as soon as possible. They will give you advice and may change the anti-sickness drug to one that works better for you.

Sore mouth

You may get a sore mouth or mouth ulcers. This can make you more likely to get a mouth infection. Use a soft toothbrush to clean your teeth or dentures in the morning, at night and after meals.

If your mouth is sore:

  • tell your nurse or doctor – they can give you a mouthwash or medicines to help
  • try to drink plenty of fluids
  • avoid alcohol, tobacco, and foods that irritate your mouth.

Tiredness (fatigue)

Feeling tired is a common side effect. Tiredness is often worse towards the end of treatment and for some weeks after it has finished. Try to pace yourself and plan your day so you have time to rest. Gentle exercise, like short walks, can give you more energy. If you feel sleepy, do not drive or operate machinery.

Laryngeal spasm

Rarely, oxaliplatin can affect the area around the voicebox (larynx). This can make you feel as though it is difficult to swallow and breathe. This might happen during treatment, or in the first few days after treatment.

This side effect can be very frightening, but it should only last for a short time. If you have breathing difficulties take long, deep breaths through your nose. This will help you to keep calm and help your breathing return to normal.

This symptom may be worse in cold temperatures. Try to avoid cold drinks and ice cubes during treatment and for a few days afterwards. It might also help to wear warm clothing and cover your nose and mouth in cold weather.

It is important to tell your doctor if you have this side effect. They may give you your infusion over a longer period of time (for example over 4 to 6 hours) in future cycles. This will reduce the chance of a laryngeal spasm happening again.

Numb or tingling hands or feet

Oxaliplatin can cause numb or tingling hands or feet. This side effect is called peripheral neuropathy. You may notice that you have difficulty doing up buttons or similar fiddly tasks. This is because the drug can affect nerve endings.

This symptom may be worse in cold temperatures. If you notice that it is caused by the cold, avoid cold drinks and wear warm clothing in cold weather. You could wear gloves, socks, and a scarf to cover your nose and mouth. Use gloves when you are taking things out of the freezer or refrigerator.

It is important to tell your doctor about any tingling or numbness. They may lower the dose of the drug to help. Sometimes this side effect may not happen with the first treatment, but after several treatments. This is called a cumulative effect.

It may continue for several months, but should improve slowly after the treatment finishes. Sometimes it is permanent.

Hair loss

Many of the chemotherapy drugs for colon and rectal cancer do not cause hair loss. But if you have the chemotherapy drug irinotecan (Campto®), you may have the following side effects:

  • your hair may get thinner
  • you may lose all the hair from your head
  • you may lose your eyelashes, eyebrows or other body hair.

Hair loss usually starts after your first or second treatment.

Your nurse can talk to you about ways to cope with hair loss. There are ways to cover up hair loss if you want to. It is important to cover your head to protect your scalp when you are out in the sun.

Hair loss is almost always temporary and your hair will usually grow back after treatment ends.

Sore hands and feet

This is sometimes called palmar-plantar or hand-foot syndrome. It can be caused by capecitabine (Xeloda®) or fluorouracil (5FU). It gets better when treatment ends.

Your doctor or nurse may prescribe creams to improve the symptoms. Using non-perfumed moisturising creams can help relieve symptoms. It can help to keep your hands and feet cool and to avoid tight-fitting socks, shoes and gloves.

Effects on memory and concentration

Sometimes chemotherapy can affect your memory, concentration and ability to think clearly. Your doctor may call these problems cancer-related cognitive changes (CRCC), or chemo brain. Chemo brain does not affect everyone and is usually mild. If you are worried about this, talk to your doctor or nurse.

Effects on the heart

Fluorouracil (5FU) and capecitabine (Xeloda®) can affect the way the heart works. If you are having one of these drugs, you may have tests to see how well your heart is working. You may have these before, during and sometimes after treatment.

Tell your doctor straight away if you:

  • have pain or tightness in your chest
  • feel breathless
  • notice changes to your heartbeat at any time.

These symptoms can be caused by other conditions, but it is important to get them checked.

Effects on sex life

Having chemotherapy can sometimes affect your sex life. Side effects like tiredness, feeling sick or weak can reduce your sex drive and make having sex difficult.

If you have a partner, it is important to try to tell them how you feel. It can also help to talk with your doctor or specialist nurse about any concerns about your sex life. They can often reassure you and support you with any problems. We have more information on effects on your sex life.


Your doctor will advise you not to get pregnant or make someone pregnant while having this treatment. The drugs may harm a developing baby.

It is important to use contraception during your treatment and for a while after treatment finishes. Your doctor, nurse or pharmacist can tell you more about this.


Some chemotherapy drugs can affect whether you can get pregnant or make someone pregnant. If you are worried about this, it is important to talk with your doctor before you start treatment.

About our information

  • Reviewers

    This information has been written, revised and edited by Macmillan Cancer Support’s Cancer Information Development team. It has been reviewed by expert medical and health professionals and people living with cancer. It has been approved by Chief Medical Editor, Professor Tim Iveson, Consultant Medical Oncologist.

    Our cancer information has been awarded the PIF TICK. Created by the Patient Information Forum, this quality mark shows we meet PIF’s 10 criteria for trustworthy health information.

Date reviewed

Reviewed: 30 April 2020
Next review: 30 April 2023

This content is currently being reviewed. New information will be coming soon.

Trusted Information Creator - Patient Information Forum
Trusted Information Creator - Patient Information Forum

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