Possible side effects of chemotherapy for colon cancer

Any side effects you have will depend on the chemotherapy drugs you are given. Your doctor or nurse will explain the possible side effects of your treatment and give you advice on how to manage them. Some side effects are easier to manage than others. It is important to remember that for most people, side effects get better once your treatment ends.

An increased risk of infection is one of the most common side effects of chemotherapy treatment. Contact the hospital immediately if you have symptoms such as a high temperature, feeling shivery, a cold, a sore throat or passing urine more often.

Some other common side effects are:

  • anaemia (reduced number of red blood cells)
  •  bruising or bleeding easily
  •  diarrhoea
  • hair thinning or loss
  • feeling sick
  • sore mouth
  • tiredness
  • soreness, numbness or tingling in the hands and feet.

Always let your doctor or nurse know about any side effects you are having. They can often give you treatments to help.

Side effects

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.

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 chemotherapy. If your white blood cell count is low, your doctor may delay your treatment for a short time.

Bruising and bleeding

Chemotherapy can reduce the number of platelets in your blood. Platelets are cells that help the blood to clot. Tell your doctor or nurse if you have any bruising or bleeding that you can’t 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 (low 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. This usually happens in the first few days of treatment. If you have this side effect, let your nurse or doctor know as they can give you medicine to help. If you still have diarrhoea after 24 hours, it is important to 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 up to two litres of fluid a 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 more than four to six episodes of diarrhoea a day, contact the hospital and speak to a doctor or nurse.

If you are taking capecitabine and your diarrhoea doesn’t settle, tell your doctor or nurse. Sometimes you may have to stop taking capecitabine until the diarrhoea gets better.

Some people may need to go to hospital to have fluids through a drip (infusion) or they may need antibiotics.

Feeling sick

You may feel sick in the first few days after chemotherapy. 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.

Feeling tired

Feeling tired is a common side effect. It 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.

Breathing and swallowing

Rarely, oxaliplatin can temporarily affect the area around the voicebox (larynx). This can cause it to spasm and make you feel as if it is difficult to breathe and swallow. It can be frightening, but only lasts for a short time. If this happens, try to take long, deep breaths through your nose. This will calm you and help your breathing return to normal.

This side effect may happen during treatment or in the first few days after treatment. It may be worse in cold temperatures. Avoid cold drinks and ice cubes during treatment and for a few days after. It might also help to wrap up warm and cover your nose and mouth in cold weather.

If you have this side effect, it is important to let your doctor know. They may give your oxaliplatin infusion over a longer time (four to six hours) in future cycles, which reduces the chance of it happening again.

Your hair

Your hair will get thinner or you may lose all the hair from your head. You may also 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 known as palmar-plantar or hand-foot syndrome. It can be caused by capecitabine or 5FU, but gets better when treatment ends. Your doctor or nurse may prescribe creams to improve the symptoms. Using non-perfumed moisturising creams can help to relieve symptoms. It can help to keep your hands and feet cool and to avoid tight-fitting socks, shoes and gloves.

Numb or tingling hands or feet

Oxaliplatin can cause this side effect, which is called peripheral neuropathy. You may notice that you have difficulty doing up buttons or similar fiddly tasks, due to effects of the drug on nerve endings.

Cold temperatures may trigger this side effect. If you notice that it is related to the cold, avoid cold drinks and wrap up warmly in the 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, as 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 instead. This is known as a cumulative effect.

It may continue for several months, but should improve slowly after the treatment finishes. In some people, it may be permanent.

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.

Changes in the way the heart works

Fluorouracil (5FU) and capecitabine 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.

If you have pain or tightness in your chest, feel breathless or notice changes to your heartbeat at any time, tell your doctor straight away. These symptoms can be caused by other conditions, but it is important to get them checked.

Your sex life

Your doctor will advise you not to become pregnant or to father a child during treatment. This is because the drugs may harm a developing baby. It is important to use effective contraception during and for a few months after chemotherapy. You can talk to your doctor or nurse about this.

Protecting your partner

If you have sex within the first couple of days of having chemotherapy, you need to use a condom. This is to protect your partner in case there is any chemotherapy in semen or vaginal fluid.

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