About side effects of chemotherapy

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. Sometimes the side effects of chemo can be unpleasant, but it can help to remember that: 

  • most side effects are short term
  • they’ll 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.

How chemotherapy causes side effects

Chemotherapy damages dividing cells. Cancer cells divide much more often than most normal cells. So chemotherapy damages cancer cells and can destroy them.

But some types of normal cells divide very often too. This happens in tissues that need a steady supply of new cells, such as the skin, hair and nails. Chemotherapy can also damage these cells, and this causes side effects. But the damaged normal tissues can repair themselves and recover.

These are some of the most common side effects:

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.

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. 

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 cancer centre 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 whose 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.

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.

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.

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 dietitian.

Some chemotherapy drugs can damage nerves, especially in your hands and feet. It can make them feel numb or cause feelings like pins and needles.

This usually improves once treatment has ended, but it can take many months and might be a permanent side effect in a small number of people.

Tell your doctor or nurse if you have any numbness or tingling.

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 might affect your sex life. You could feel tired and lose interest in sex.

Some chemotherapy drugs can affect fertility. If you’re hoping to have a child, discuss it with your doctor before you start treatment. There might be steps that you and your doctor can take to help keep your fertility.

Sickness caused by chemotherapy can start within a couple of hours of starting your treatment and only last a day or so. Or it can come on more than 24 hours after the start of treatment. This is called delayed onset nausea and vomiting and usually lasts about a week.

Sometimes sickness doesn’t start until you have had your first few cycles of chemotherapy. It all depends on the chemotherapy drugs you have and how you react to them. This can vary from person to person.

If you are being sick with chemotherapy, do tell your doctor or chemotherapy nurse. There are lots of different anti sickness medicines and some work better for some people than others.

Some chemotherapy drugs make some of your hair fall out, so that your hair is thinner.

Other chemotherapy drugs make all the hair on your head and body fall out, including eyebrows and eyelashes.

Losing your hair can be distressing. But it's temporary and the hair starts to grow back a few weeks after treatment ends.

Some chemotherapy drugs can make your skin dry and sensitive. Some may cause rashes. You may find that your skin is more likely to burn in the sun or react to chemicals for up to a year after treatment. So be careful when you’re in the sun, wear a hat and at least factor 15 sun protection.

If you have dry skin, avoid swimming while you are having treatment. Some people find that their nails also change and become dry, ridged or brittle or have white lines on them.

After cancer treatment, some people notice changes in their memory, concentration and the way they think. These changes are called mild cognitive impairment (MCI) or cognitive dysfunction. Some people call them 'chemo brain' or 'chemo fog'.

It's not clear exactly what causes these memory and concentration changes in people with cancer. So calling them chemo brain may not be accurate.

It's possible that these problems might be due to other cancer treatments. Or more recent research has shown that some people with cancer have similar problems before they start any treatment. So these changes could be due to the cancer itself. 

Researchers are trying to find out:

  • what causes chemo brain
  • how health professionals and people with cancer can best manage the symptoms of cognitive impairment

Some chemotherapy drugs can cause bowel changes such as diarrhoea or constipation while you are taking them. Speak to the team looking after you if have any changes to your bowel habit. 

Late side effects

Most chemotherapy side effects are temporary and disappear once your treatment is over.

But for some people, chemotherapy can cause long term changes in the body. Some of these changes may happen months or many years after the treatment has finished.

Late side effects can include early menopause, infertility, changes to feeling in your hands and feet (peripheral neuropathy) and heart and lung problems. Your doctor and chemo nurse can talk to you about the risk of late side effects with the drugs you're having.

This page is due for review. We will update this as soon as possible.

  • Handbook of Cancer Chemotherapy (8th edition)
    R T Skeel and S N Khleif
    Lippincott, Williams and Wilkins, 2011

  • Handbook of Systemic Treatments for Cancer (8th edition)

    L Doygherty, A McWhirter and P Jones

    Lilly Oncology UK 2014

  • Oncology/Haematology 24-Hour Triage Toolkit
    UK Oncology Nursing Society, November 2016

Last reviewed: 
06 Aug 2020
Next review due: 
06 Aug 2023

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