Chemotherapy is a type of drug treatment that uses chemicals to stop cancer cell growth. These chemicals affect any cell in the body that grows rapidly. This includes tumour cells but also hair growth cells and bone marrow, among others.

Chemotherapy is usually administered through an IV directly into the bloodstream.

Your chemotherapy regimen should achieve a balance between the most effective cancer treatment and your quality of life. Some types of chemotherapy have a lot of side effects. Many are mild and can be managed at home. However, if you are not fit or feel very sick from the cancer, side effects can be quite severe. They should be considered seriously if you cannot recover from your illness and the goal is to optimise your quality of life.

Side effects

There are more than 100 different chemotherapy drugs. This page tells you about the side effects that they may cause. But different drugs cause different side effects. Your doctor or nurse will tell you about specific side effects of your own treatment.

It’s important to remember that you probably won’t get every side effect listed. For some people the effects are mild. The side effects of chemo can be unpleasant, but it can help to remember that:

  • most side effects are short-term
  • most side effects begin to go once the treatment has finished
  • you can have medicines to reduce most side effects

Let your nurse or doctor know if you have side effects that are troubling you.

  • Find side effects of specific drugs here

Tiredness and weakness

Chemotherapy can make you feel very tired. The tiredness can increase as you go through your treatment and could last for quite a few months after the treatment ends. This is called fatigue.

You might also feel weak and as though you have no energy. This is called lethargy and can be part of fatigue.

A drop in the number of platelets

You might notice you:

  • bruise more easily
  • have nosebleeds
  • have bleeding gums when you brush your teeth

This is due to a drop in the number of platelets that help clot your blood. If your platelets get very low you may have lots of tiny red spots or bruises on your arms or legs called petechiae. Tell your doctor or nurse straight away if you have petechiae. You’ll have a platelet transfusion if your platelet count is very low. It is a drip of a clear fluid containing platelets. It takes about 15 to 30 minutes. The new platelets start to work right away.

An increased risk of getting an infection

Chemotherapy drugs often stop the bone marrow from making enough white blood cells. White blood cells are part of your defence against infection.

When your white blood cells are low, bacteria can quickly increase in the blood. You might not have enough white blood cells to fight the bacteria. So a minor infection can become life-threatening within hours.

Signs of infection

It’s important to tell your hospital treatment team urgently if you have any signs of infection such as:

  • an increase in your temperature to 38 degrees Celsius or higher
  • feeling cold and shivery
  • headaches
  • aching muscles
  • a cough
  • a sore throat
  • pain passing urine
  • a lower than normal temperature

Contact your hospital immediately. Some infections can be life-threatening if you don’t have treatment quickly. You might need antibiotics by injection or through a drip to control the infection. Tablets might not be enough.

Neither you or your doctor can tell you if your fever could develop into a severe illness. So all possible infections must be treated urgently. Your doctor won’t think you are making a fuss about something minor. It is better to be on the safe side.


Some chemotherapy drugs can affect your hearing. This usually gets better when treatment finishes, but your doctor may reduce the dose of your treatment or change your treatment.

Tell your doctor or nurse if you have any changes to your hearing.

Breathlessness and looking pale

Chemotherapy makes the level of red blood cells fall (anaemia). Red blood cells contain haemoglobin, which carries oxygen around the body. When the level of red blood cells is low you have less oxygen going to your cells. This can make you breathless and look pale. Tell your doctor or nurse if you feel breathless.

You have regular blood tests to check your red blood cell levels. You might need a blood transfusion if the level is very low. After a transfusion, you will be less breathless and less pale.

You can also feel tired and depressed when your blood count is low and feel better once it is back to normal. The levels can rise and fall during your treatment. So it can feel like you are on an emotional and physical roller coaster.

Eating and drinking

Many chemotherapy drugs can make you feel sick or be sick. But anti sickness medicines can usually control this well.

  • Some drugs can make the lining of your mouth very sore or cause small mouth ulcers.
  • Some can also change your sense of taste for a while.
  • Some chemotherapy drugs might irritate the lining of your bowel and cause diarrhoea. This usually happens in the first few days after treatment. It can be well controlled with medicines.
  • Some chemotherapy drugs and some of the medicines to control sickness can cause constipation.

Kidneys, liver, heart and lungs

Some chemotherapy drugs can cause changes in the way your kidneys, liver, heart or lungs work. The changes are usually temporary and go back to normal when your treatment ends.

But for some people the changes may be permanent. Your doctor can tell you if your drugs are likely to cause any changes.

Some chemotherapy drugs can increase your risk of developing blood clots. Contact your hospital immediately if you become breathless or have swelling in your leg.

Chemotherapy can affect your appetite. Don’t worry too much if you really don’t feel like eating for a few days after treatment. You can make up for lost calories later. However, it is important to drink.

Your doctor or nurse can answer any questions about what you should or shouldn’t eat. And if you have a problem with diet, digestion or weight loss, talk to your doctor, cancer nurse or dietician.

Other common side effects of chemotherapy:

  • Hair loss—will usually grow back in 3-6 months
  • Upset stomach (nausea)
  • Mouth sores
  • Sensory changes in taste or hearing
  • Changes in skin or nails
  • Tingling in fingers or toes
  • Anaemia
  • Fluid retention
  • Vomiting
  • Allergic reactions
  • Muscle pain
  • Diarrhoea

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© Cancer Research UK [2002] All right reserved. Information taken 23/02/2018.