Side effects of chemotherapy

Side effects of chemotherapy vary from one person to another. It is difficult to predict how you will feel and what side effects you will have. Some people only have mild side effects, but others might have severe side effects.

Your nurses, doctor and pharmacist will look after you during treatment and afterwards. They monitor you and treat any side effects that you might have.

Ask your treatment team to go through the possible side effects of treatment with you.

Side effects

The side effects you have depend on:

  • which drugs you have
  • how much of each drug you have
  • how you react

Common side effects include:

Increased risk of infection

Increased risk of getting an infection is due to a drop in white blood cells. Symptoms include a change in temperature, aching muscles, headaches, feeling cold and shivery and generally unwell. You might have other symptoms depending on where the infection is.

Infections can sometimes be life threatening. You should contact your advice line urgently if you think you have an infection. 


You might be breathless and look pale due to a drop in red blood cells. This is called anaemia.

Breathlessness can also be a sign of a blood clot in your lungs (pulmonary embolism). Other symptoms of blood clots include pain in your chest or upper back and coughing up blood. Tell your doctor immediately or go to A&E if you have any symptoms of a blood clot.

Bruising and bleeding

This is due to a drop in the number of platelets in your blood. These blood cells help the blood to clot when we cut ourselves. You may have nosebleeds or bleeding gums after brushing your teeth. Or you may have lots of tiny red spots or bruises on your arms or legs (known as petechiae).

You can also have bruising and bleeding if you are taking high doses of steroids. Or if you have taken them for a long period of time. 

Feeling or being sick

Feeling or being sick is usually well controlled with anti sickness medicines. Avoiding fatty or fried foods, eating small meals and snacks, drinking plenty of water, and relaxation techniques can all help.

It is important to take anti sickness medicines as prescribed even if you don’t feel sick. It is easier to prevent sickness rather than treating it once it has started.

Tiredness (fatigue)

Tiredness and weakness (fatigue) can happen during and after treatment - doing gentle exercises each day can keep your energy up. Don't push yourself, rest when you start to feel tired and ask others for help.

Hair thinning or hair loss

Your hair may thin but you’re unlikely to lose all your hair. This usually starts after your first or second cycle of treatment. It is almost always temporary and your hair will grow back when you finish your treatment.

Constipation or diarrhoea

Tell your doctor or nurse if you have diarrhoea or constipation. They can give you medicine to help. 

Mouth sores and ulcers

Mouth sores and ulcers can be painful. It helps to keep your mouth and teeth clean, drink plenty of fluids, avoid acidic foods such as oranges, lemons and grapefruits, and chew gum to keep the mouth moist. Tell your doctor or nurse if you have ulcers.

An allergic reaction

Some people can have a severe allergic reaction with swelling of the face, lips, tongue and throat. You may also have difficulty breathing. Tell your nurse straight away if you have any of these symptoms.

Chemotherapy and alcohol

Some chemotherapy drugs such as procarbazine and lomustine can react with alcohol and make you feel unwell. It can cause:

  • sickness
  • headaches
  • difficulty breathing
  • drowsiness

When you go home

Chemotherapy for a brain tumour can be difficult to cope with. Tell your doctor or nurse about any problems or side effects that you have. You will have a number to call if you have any problems at home.

Last reviewed: 
07 Nov 2019
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