Side effects of chemotherapy

Chemotherapy treatment can cause different side effects. If you take a single chemotherapy tablet, side effects will usually be mild. Some side effects are more common than others but you won’t have them all. They can be reduced and controlled with drugs. Your doctor or nurse can tell you how to manage them. The most frequent ones include:

  • increased risk of infection
  • anaemia (reduced number of blood cells)
  • hair loss of thinning
  • feeling sick or vomiting
  • tiredness.

Most side effects are short term and will improve gradually when the treatment is over.

One of the most common side effects is an increased risk of infection. Always contact the hospital and speak to a nurse or doctor if:

  • you have a temperature
  • you suddenly feel unwell
  • you have any symptoms of an infection – a cold, sore throat, cough, passing urine frequently (urine infection), diarrhoea, feeling shivery and shaking etc.

Understanding the side effects of chemotherapy

If you are taking a single chemotherapy tablet, any side effects you have will usually be mild. Treatment with a combination of two or more chemotherapy drugs may cause more troublesome side effects.

Risk of infection

Chemotherapy can reduce the number of white blood cells, which help fight infection. If the number of your white blood cells is low, you'll be more prone to infections. A low white blood cell count is called neutropenia.

Always contact the hospital immediately on the 24-hour contact number you've been given if:

  • You develop a high temperature – this may be over 37.5°C (99.5°F) or over 38°C (100.4°F) depending on the hospital's policy. Follow the advice that you have been given by your chemotherapy team.
  • You suddenly feel unwell, even with a normal temperature.
  • You feel shivery and shaky.
  • You have any symptoms of an infection such as a cold, sore throat, cough, passing urine frequently, diarrhoea.

If necessary, you'll be given antibiotics to treat any infection. You'll have a blood test before each cycle of chemotherapy to make sure your white blood cells have recovered. Occasionally, your treatment may need to be delayed if the number of your white blood cells is still low.

Anaemia (reduced number of red blood cells)

Chemotherapy may reduce the number of red blood cells (haemoglobin) in your blood. A low level of red blood cells is called anaemia, which can make you feel very tired and lethargic. You may also become breathless. Let your doctor know if you get these effects.

Bruising and bleeding

Chemotherapy can reduce the number of platelets in your blood. Platelets are cells that help the blood to clot. If you develop any unexplained bruising or bleeding, such as nosebleeds, bleeding gums, blood spots or rashes on the skin, contact your doctor or the hospital straight away.

Feeling sick (nausea)

Some chemotherapy drugs can make you feel sick (nauseated) or possibly be sick (vomit). Your haematologist will prescribe anti-sickness (anti-emetic) drugs to prevent this. Let your doctor or nurse know if your anti-sickness drugs are not helping, as there are several different types you can try.

Sore mouth

Chemotherapy can cause mouth problems such as a sore mouth, mouth ulcers or infection. Drinking plenty of fluids, and cleaning your teeth regularly and gently with a soft toothbrush can help to reduce the risk of this happening. Your chemotherapy nurse will explain how to look after your mouth to reduce the risk of problems. They can give you mouthwashes, medicines and gels to help.

We have some useful tips on coping with a sore mouth during chemotherapy.

Tiredness (fatigue)

You’re likely to become tired and have to take things slowly. Try to pace yourself and save your energy for things that you want to do or that need doing. Balance rest with some physical activity – even going for short walks will help increase your energy levels. We have helpful tips on coping with tiredness.

Hair loss

Some chemotherapy drugs may cause hair loss. Some people may have complete hair loss including eyelashes and eyebrows. Others may only experience partial hair loss or thinning. It depends on what chemotherapy drugs you are having (your doctor or nurse can tell you more about what to expect). If you do experience hair loss your hair should start to grow back within about 3–6 months of the end of treatment. It may grow back straighter, curlier, finer, or a slightly different colour than it was before. Your nurse can give you advice about coping with hair loss and how to look after your scalp.

Some chemotherapy departments may offer scalp cooling to reduce hair loss during chemotherapy. We have more information about coping with hair loss.


It’s not advisable to become pregnant or father a child while having any of the chemotherapy drugs used to treat leukaemia as they may harm the developing baby. It is important to use effective contraception during your treatment and for up to a year afterwards. You can discuss this with your doctor or specialist nurse.

Condoms should be used during sex for the first 48 hours after chemotherapy. This is to protect your partner from any of the drug that may be present in semen or vaginal fluid.

Effects on fertility

Unfortunately, some chemotherapy drugs can cause infertility. Infertility is the inability to become pregnant or to father a child. This may be temporary or permanent, depending on the treatment that you have.

It’s important to discuss your infertility risk with your cancer doctor before you start chemotherapy. If you have a partner, it’s a good idea to include them at this discussion.

Although chemotherapy can affect fertility, it’s still possible for a woman to get pregnant or for a man to get his partner pregnant during chemotherapy. It’s important to avoid pregnancy when you’re having chemotherapy as the drugs could harm a developing baby.

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