Chemotherapy side effects

Chemotherapy uses anti-cancer drugs, called cytotoxic drugs, to target the cancer cells. Unfortunately, they also affect healthy cells which is why side effects can happen.

For more information about the potential side effects of your child's treatment, talk to your specialist. In many cases it is possible to reduce or treat side effects, providing you or your child let your care team know how they are getting on with their treatment.

Some people don’t have many problems with chemotherapy. But if your child doesn’t have side effects, it doesn’t mean the treatment isn’t working.


Chemotherapy may make your child vomit or feel sick. Your specialist will be able to prescribe anti-sickness drugs (also called anti-emetic drugs) to reduce this side effect.

Diarrhoea or constipation

The chemotherapy drugs may affect how your child's bowel works leading to constipation or diarrhoea. This can be helped by laxatives or anti-diarrhoea drugs.


Your child may feel very tired during their chemotherapy treatment, and for a number of months afterwards. They may need to rest more often and cut back on activities.

Mouth ulcers and taste changes

The chemotherapy drugs can cause a sore mouth or mouth ulcers. Your child may also experience a bitter taste in their mouth. These problems should disappear after they finish treatment, but in the meantime it is important to look after your child's mouth by cleaning their teeth regularly but gently, having frequent dental check-ups and checking their mouth daily for sores.

Changes in appetite

You may find that your child doesn't feel like eating during their treatment, or that their eating habits change. However, it is really important to maintain their weight and for them to drink plenty of fluids to keep well during their treatment.

If your child is having problems with eating, ask if you can speak to the hospital dietician about how your child can get the nutrition and calories they need.

Hair loss

Hair loss usually happens two to three weeks after the first course of chemotherapy. It doesn’t usually fall out all at once. Some people may lose all their hair, others may find it gets thinner or falls out in patches. Your child's hair will begin to grow back once their treatment has stopped.

Skin problems

Chemotherapy can make your child's skin very sensitive to the sun and chemicals such as the chlorine in swimming pools. Your child's skin may develop a rash or change colour. Talk to your specialist if you are concerned.

Blood changes

Chemotherapy also affects the bone marrow in bones. This is where your child's blood cells are made. When your child has chemotherapy, the number of blood cells they have in their body (their ‘blood count’) will drop.

Low number of red blood cells

A low number of red blood cells is called anaemia. If your child becomes anaemic, they may feel tired, breathless or dizzy. If their body doesn’t make enough red blood cells again, your child may need a blood transfusion.

Low number of white blood cells

If your child has a low number of white blood cells, they may develop infections more easily than normal. You can’t have a transfusion of white blood cells, so your child needs to take extra care to avoid infections while their body creates some more.

This means avoiding crowded places and people who are sick, and trying to keep themselves as healthy as possible. You will be told who to contact should your child have a temperature or feel ill. It is essential that you get in touch immediately for advice.

Low number of platelets

Platelets are tiny cells that prevent bruising or bleeding. A low number of platelets is called thrombocytopenia. If your child is thrombocytopenic, they may bleed or bruise more easily, and bleed for longer than normal if they cut themselves. Your child may need a platelet infusion if their platelet count drops too low.


Some chemotherapy drugs may permanently affect your child's ability to have children in the future. However, this is not true for every chemotherapy drug. It is important to talk to your specialist about any options that are available to your child.

Longer-term effects

Many of these side effects are temporary and should gradually improve once your child completes their treatment. However, some individual drugs may cause particular longer-term effects on the heart, renal system, hearing or other organs.

If these drugs are used, your specialist will monitor your child throughout their treatment to see the effect that they are having on their body, and may alter the treatments or dosage if necessary.

Where next?

Updated November 2017, next review due 2019.