Possible side effects of chemotherapy

Chemotherapy treatment can cause different side effects. These vary depending on the drugs you have. Your doctor or nurse will tell you which ones you are more likely to get.

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
  • feeling sick or vomiting
  • mouth ulcers
  • 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 such as a cold, sore throat, cough, passing urine frequently (urine infection), feeling shivery and shaky, or diarrhoea.

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. Your doctor may prescribe you antibiotics and other drugs to help prevent an infection. Your nurse may give you injections of a drug called G-CSF under the skin. It encourages the bone marrow to make more of a type of white blood cells called neutrophils.

While you are an inpatient your nurse will check your temperature regularly and monitor you for any other signs of infection. Always let them know if you feel unwell or cold and shivery.

If you are at home contact the hospital immediately on the 24-hour contact number you’ve been given and speak to a nurse or doctor if:

  • you develop a high temperature, which may be over 37.5°C (99.5°F)
  • 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 (urine infection), or diarrhoea.

You’ll be given antibiotics to treat any infection. You’ll have regular blood tests to check the levels of all your blood cells.

Your treatment may need to be delayed if the number of your white blood cells is low.

We have more information on how to avoid infection when you have low immunity, which you may find helpful.

Increased bleeding and bruising

If the number of platelets in your blood is reduced you may bruise very easily, or bleed more than usual from minor cuts or grazes.

Tell your hospital doctor or nurse about this and contact them straight away if you notice or have:

  • nosebleeds
  • bleeding gums
  • tiny red or purple spots on the skin (petechiae) that sometimes cluster to make a rash.

If your platelets are low, particularly during a period at home, you’ll need to be careful to avoid injuries. Wear protective gloves when doing anything around the house or gardening. Be careful to avoid bumping into things or tripping. Use a soft toothbrush to protect your gums from bleeding and don’t floss.

You will probably need platelet transfusions at times during your treatment. These are given by a drip (infusion). The platelets start working immediately to prevent bruising and bleeding.

Anaemia (reduced number of red blood cells)

Chemotherapy reduces the number of red blood cells in your blood. This can make you feel very tired and lacking in energy. You may also become breathless and feel dizzy. These symptoms happen because the red blood cells contain haemoglobin, which carries oxygen around the body. You’re likely to need blood transfusions to help with this. Some people find they feel better almost as soon as they have had the transfusion.

Feeling sick or being sick

Some chemotherapy drugs can make you feel sick (nauseated) or possibly be sick (vomit). Your cancer specialist 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. We have more information about controlling nausea and vomiting.

Sore mouth

Your mouth may become sore or dry, or you may notice ulcers during treatment. Mouth ulcers can become infected. Drinking plenty of fluids and cleaning your teeth regularly and gently with a soft toothbrush can help to reduce the risk of this happening. Some people find sucking on ice may be soothing.

Always let your doctor or chemotherapy nurse know if you have mouth ulcers, or any problems with your mouth. They can give you mouthwashes, medicines and gels to help with the pain and clear or prevent any infection.

We have more information on mouth care during chemotherapy.


Some chemotherapy drugs and also anti-sickness drugs and pain killers can cause constipation. Let your nurse or doctor know if this happens so they can prescribe drugs to prevent or treat this.

Try to eat more fibre, raw fruits, cereals and vegetables and drink plenty of liquid. Gentle exercise, such as short walks, can help to improve constipation.


If you have diarrhoea, contact the hospital for advice. Try to drink at least two litres (three and a half pints) of fluids every day. It can help to avoid alcohol, caffeine, milk products, high-fat foods and high-fibre foods.


You will probably feel very tired and need a lot of rest. Try to balance this with some gentle exercise, such as short walks, which will help. You’ll probably tire easily for some months after your treatment, but this will gradually get better.

We have more information about coping with fatigue.

Hair loss

You usually lose all the hair on your head during intensive chemotherapy treatment for ALL. Your eyelashes, eyebrows and other body hair may also thin or fall out. This usually starts after your first or second cycle of chemotherapy. It is almost always temporary and your hair will grow back over a few months once your treatment is over or during maintenance treatment (if you have this).

It is important to cover your head to protect your scalp when you are out in the sun until your hair grows back. Your nurse can give you advice about coping with hair loss.

Skin changes

If your skin feels dry, try using an unperfumed moisturising cream every day. During treatment and for several months afterwards, you’ll be more sensitive to the sun and your skin may burn more easily than usual. You can still go out in the sun, but use a suncream with a sun protection factor (SPF) of at least 30, and cover up with clothing and a hat. Your skin may darken. It will return to its normal colour after you finish treatment. Always tell your doctor or nurse about any skin changes. They can give you advice and may prescribe creams or medicines to help. Any changes to your skin are usually temporary and improve when treatment finishes.

Effects on the heart

Some of the drugs used to treat ALL may affect the heart muscle. The doses of the chemotherapy drugs are very carefully monitored to reduce the risk of this happening. You may have heart tests from time to time.

Sex and chemotherapy

Having chemotherapy can affect your sex life. Side effects such as tiredness, feeling sick or weak can reduce your sex drive and make having sex difficult. Chemotherapy shouldn’t have a long-term effect on your sex life. The side effects will gradually wear off when your treatment is finished.

Usually there’s no medical reason to stop having sex during chemotherapy. But if you have low platelets or a low white blood cell count, you may be advised to avoid penetrative sex until your blood count improves.

Protecting your partner

It’s not known if chemotherapy drugs pass into semen or vaginal fluids. Doctors usually advise you to use condoms for a few days after chemotherapy to protect your partner.

Remember that cancer can’t be passed on to your partner and sex won’t make the cancer worse.


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.


Your immunity will be reduced when you are having treatment for ALL. Because of this, your doctor may suggest that people in your household be vaccinated against common illnesses such as flu. Some types of vaccine contain live parts of a virus. We have more information on having vaccinations after treatment.

Back to Side effects of chemotherapy

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Chemo brain describes changes in memory, concentration and the ability to think clearly. These changes can sometimes happen during or after cancer treatment.