Possible side effects

Chemotherapy treatment can cause side effects. Not all drugs cause the same side effects and some people may have very few. Always tell your doctor or nurse about the side effects you are having as there are ways they can be controlled.

Possible side effects include:

  • risk of infection – always get in touch with the hospital if you feel unwell or have a temperature over 37.5°C (99.5°F)
  • bruising and bleeding
  • anaemia – low number of red blood cells, which makes you feel tired
  • feeling sick
  • tiredness
  • hair loss
  • sore mouth and taste changes
  • bowel changes
  • numbness or tingling in your hands or feet.

Most side effects stop or gradually go away when chemotherapy is over.

Chemotherapy drugs can affect sperm and may be present in semen after treatment. You should use condoms if you have sex within 48 hours of having chemotherapy. You should avoid fathering a child for at least a few months after treatment. Chemotherapy may also affect your fertility. Your doctor will discuss this with you before your treatment starts. They can give you information about storing sperm if needed.

Side effects

Chemotherapy drugs may cause unpleasant side effects, but these can usually be well controlled with medicines and will usually go away once treatment has finished. Not all drugs cause the same side effects and some people may have very few. You can talk to your doctor or nurse about what to expect from the treatment that’s planned for you.

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.

Always 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.

If necessary, you’ll be given antibiotics to treat any infection. You’ll have a blood test before each cycle of chemotherapy to make sure your white blood cells have recovered. Occasionally, your treatment may need to be delayed if the number of white blood cells is still low.

After chemotherapy, your nurse may give you injections of a drug called G-CSF under the skin. This encourages the production of white blood cells and reduces the risk of infection.

I was dreading chemotherapy and worried about what would happen. Now I look back and I think, actually, it wasn’t that bad for me.


Bruising and bleeding

Platelets are cells that help the blood to clot. 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. Contact them straight away if you have nosebleeds, bleeding gums or tiny red or purple spots on the skin (called petechiae).

Anaemia (reduced number of red blood cells)

Chemotherapy may reduce the number of red blood cells (haemoglobin) in your blood. A low level of red blood cells is known as anaemia, which can make you feel very tired and lethargic. You may also become breathless.

Feeling sick (nausea) and vomiting

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 different types you can try.

Tiredness (fatigue)

You’re likely to become tired and have to take things slowly. Try to pace yourself and save your energy for things that you want to do or that need doing. Balance rest with some physical activity – even going for short walks will help increase your energy levels. We have helpful tips on coping with tiredness.

Hair loss

Some chemotherapy drugs may cause hair loss. Some people may have complete hair loss including eyelashes and eyebrows. Others may only experience partial hair loss or thinning. It depends on what chemotherapy drugs you are having (your doctor or nurse can tell you more about what to expect). If you do experience hair loss your hair should start to grow back within about 3–6 months of the end of treatment. It may grow back straighter, curlier, finer, or a slightly different colour than it was before. Your nurse can give you advice about coping with hair loss and how to look after your scalp.

Some chemotherapy departments may offer scalp cooling to reduce hair loss during chemotherapy. We have more information about coping with hair loss.

Sore mouth

Your mouth may become sore (or dry), or you may notice small ulcers during treatment. Some people find that sucking on ice may be soothing. Drinking plenty of fluids, and cleaning your teeth regularly and gently with a soft toothbrush, can help to reduce the risk of this happening. Tell your nurse or doctor if you have any of these problems, as they can prescribe mouthwashes and medicine to prevent or clear mouth infections.

Taste changes

You may notice that food tastes different. Some people describe having a metallic taste in their mouths. Normal taste usually comes back after treatment finishes. A dietitian or specialist nurse at your hospital can give you advice about ways of coping with this side effect.

Bowel changes

Chemotherapy can cause constipation or diarrhoea. Constipation can usually be helped by drinking plenty of fluids, eating more fibre in your diet and doing some gentle exercise. You may need to take medicine to help (laxatives). Your doctor can prescribe these or you can buy them at a pharmacy. Diarrhoea can usually be easily controlled with medicine but tell your doctor if it’s severe or continues. It’s important to drink plenty of fluids if you have diarrhoea.

Effects on the nerves

Some chemotherapy drugs can affect the nerves in your hands or feet. This can cause tingling or numbness, or a feeling like pins and needles. This is called peripheral neuropathy.

It’s important to let your doctor know if this happens. They may need to change the dose of the chemotherapy drug. Usually, peripheral neuropathy gradually gets better when chemotherapy is over but sometimes it’s permanent.


Your doctor will advise you not to father a child while having chemotherapy as the drugs can affect your sperm. It’s important to use effective contraception during your treatment and for at least a few months afterwards. You can discuss this with your doctor or nurse.


You’re usually advised to use condoms if you have sex within 48 hours of chemotherapy. This is to protect your partner in case the drugs are present in semen.


Some chemotherapy drugs can affect your ability to father a child. If chemotherapy is likely to make you infertile and you want to have children, it may be possible to store sperm before treatment begins. If your fertility is a concern, it’s important to talk to your doctor about this before your treatment starts.

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