Side effects of chemotherapy

Chemotherapy will affect each man differently, and you might not get all the possible side effects. Most of them are temporary and will gradually go away after you finish treatment. Before you start treatment, talk to your doctor or nurse about the side effects. Knowing what to expect can help you deal with them.

Why does chemotherapy cause side effects?

Like all treatments, chemotherapy can cause side effects. These will affect each man differently, and you might not get all the possible side effects. Most of them are temporary and will gradually go away after you finish treatment. Before you start treatment, talk to your doctor or nurse about the side effects. Knowing what to expect can help you deal with them.

Chemotherapy targets and kills cells that grow too quickly, such as cancer cells. But it can also affect some healthy cells that also grow quickly, and this can cause side effects. These include the cells in:

• the bone marrow
• the lining of the mouth
• parts of the gut, such as the bowel
• hair follicles – which are responsible for hair growth
• finger and toe nails.

Chemotherapy affects how well your bone marrow works. Bone marrow is the spongy material that fills some of your bones. It makes red and white blood cells and other cells called platelets. There may be a drop in the levels of any of these cells during chemotherapy, and this can cause side effects. This usually happens about 7 to 10 days after each treatment session.

Side effects can happen with all types of chemotherapy. The most common side effects are described here. But there are others that are less common, and each type of chemotherapy can also cause its own particular side effects. Tell your doctor or nurse about any side effects as soon as you get them. There are treatments available and things you can do yourself to help manage them.

Infections

During chemotherapy your body might be less able to fight off infections. This is caused by a drop in the number of white blood cells in your body. You might hear this called neutropenia. White blood cells are part of your immune system and help fight infection. It’s important to contact the hospital immediately if you think you might have an infection because it could make you very unwell or be fatal if it’s not treated.

It’s important to lower your chances of catching infections from other people. Try to avoid close contact with people who are ill or have an infection and make sure you wash your hands regularly. But you can still spend time with people who are well and it’s fine to have normal contact with your family and friends. It’s important to carry on doing things you enjoy with people you are close to. Ask your doctor for more advice on avoiding infections.

Feeling breathless, tired or weak

This can be caused by a drop in the number of red blood cells, which means not enough oxygen is carried around the body. This is known as anaemia. If this happens, your doctor may delay your next treatment session to give your red blood cells time to recover. If your level of red blood cells falls very low, you may need to have a blood transfusion.

Bleeding and bruising more easily than normal

This can be caused by a drop in the number of platelets in your blood. Platelets help your blood to clot. A low level of platelets is called thrombocytopenia. You may get nose bleeds or bleeding gums. There are things you can do to lower the risk of bleeding, such as using a softer toothbrush, and an electric shaver rather than a razor. Some men with advanced prostate cancer pass some blood in their urine, and chemotherapy can make this worse.

Extreme tiredness (fatigue)

Many men say that fatigue is one of the hardest side effects to cope with. Fatigue is extreme tiredness or exhaustion, which makes it hard to carry out your daily activities.

During a course of chemotherapy, your energy levels may go up and down. Fatigue is usually worse during the week after each treatment session but then gradually improves. Fatigue usually gets worse as you have more sessions of chemotherapy.

After finishing a course of chemotherapy, most men find their energy levels improve. But for some, fatigue can be long-lasting.

Sometimes there is a specific cause for your tiredness, like low levels of red blood cells. But tiredness can also be caused by things other than your treatment. For example, the cancer itself can make you feel tired, and so can feeling anxious or depressed.

Our Specialist Nurses are here to support you. They can talk to you in depth about your experience of fatigue and the impact it is having on day-to-day life and discuss ways to better manage your tiredness. You can also visit our interactive online guide for ways to deal with fatigue.

Feeling and being sick (nausea and vomiting)

Chemotherapy for prostate cancer is not as likely to make you feel sick as some other types of chemotherapy. If you do feel sick, your doctor can prescribe anti-sickness medicines (anti-emetics). Your doctor may consider different treatments or medicines if you continue to feel sick after anti-sickness medications.

Your doctor or nurse can also talk you through other things that might help, such as foods to eat or avoid, and relaxation techniques.

If the smell of food is putting you off eating, try to avoid strong-smelling foods and choose cold foods as they don’t usually smell as much. If possible, ask someone to make your meals for you. You may also find it helps to avoid fried, greasy or very sweet foods. Some people find things flavoured with peppermint or ginger can help, such as herbal teas or sweets.

Loss of appetite

You might lose your appetite during chemotherapy. This can happen because of some side effects, such as feeling sick or having a sore mouth. Chemotherapy can also make food taste different – it might taste more salty, bitter or metallic, or it might lose its taste. Some people find sucking on boiled sweets, fresh or tinned pineapple or taking sips of ginger beer can leave a pleasant taste in their mouth.

If you don’t feel like eating much, it’s important to drink plenty of fluids and to find foods that you enjoy. Eating small meals and having regular snacks that are high in calories can also help you get the energy and nutrients you need.

The steroids you take with your chemotherapy should help improve your appetite. But if you’re having problems eating a balanced diet or if you’re losing weight, talk to your doctor or nurse. They may be able to refer you to a dietitian who specialises in helping people with cancer.

Sore mouth

Some chemotherapy drugs can make your mouth sore, but this isn’t common. You may get ulcers or inflamed gums, which can be painful. There are things that might help.

• Brush your teeth gently twice a day with a soft toothbrush and use mouth washes regularly.
• Be very careful when flossing, and avoid using tooth picks.
• Choose soft, moist foods and avoid foods that are acidic, spicy, very hot or very cold.
• Try drinking through a straw.

Your nurse can give you more information about taking care of your mouth. If it gets very sore, your doctor might prescribe pain-relieving drugs.

Bowel problems

Some types of chemotherapy may make your bowel movements loose and watery (diarrhoea). This usually happens in the first few days after treatment.

Other chemotherapy drugs and some anti-sickness medicines can make it difficult to empty your bowels (constipation). Bowel problems can usually be controlled with medicines or changes to what you eat, so let your doctor or nurse know about any problems you’re having.

Make sure you’re drinking enough water – about eight glasses (two litres) a day. This will help to replace water that’s lost with diarrhoea, and will also help prevent constipation. It might also be a good idea to avoid fatty, fried and spicy foods, as some men find they can make diarrhoea worse.

Sometimes diarrhoea can be caused by an infection. If you have diarrhoea and you feel unwell or have a temperature, contact your medical team straight away.

Read more about how to manage bowel problems.

Hair loss

Hair loss is a temporary side effect of some chemotherapy drugs. It affects people differently. Some men lose all their hair but many just notice some thinning or have no hair loss at all. Hair loss happens gradually and tends to start two or three weeks after treatment starts. You can lose hair anywhere on your body. Your hair will usually begin to grow back after you’ve finished treatment. Some men choose to wear a hat or wig until their hair has grown back.

To help reduce hair loss, scalp cooling may be suitable for some people. This involves wearing a special cap during each treatment session. The cap is filled with a cold gel or connected to a small cooling system. But it doesn’t work for everyone and may not be available in every hospital. If you’re interested in scalp cooling, speak to your doctor or nurse.

Sensitive skin

You may notice some redness, dryness or irritation to your skin if you’re having chemotherapy. Your skin might also be more sensitive to the sun and could burn easily. So even on a cold day, if the sun is shining wear a hat or use sun block. It’s important to protect the skin on your head from the sun, especially if you have hair loss.

Fluid retention

This can cause your ankles or legs to swell, or you might feel a bit bloated. This can also be a side effect of steroids. If it does happen, it should improve after you finish treatment.

Numbness or tingling in the hands and feet

Chemotherapy can affect your nerves (peripheral neuropathy). This can cause numbness or tingling in your hands and feet. This usually improves slowly, a few months after treatment finishes.

It’s important to tell your doctor or nurse if you get this. If it’s severe, your doctor might decide to reduce the amount (dose) of chemotherapy you have at each treatment session. Or they might suggest a different treatment.

Numbness and tingling can have other causes, including the cancer itself. You may need some tests to check what’s causing it.

Changes to your nails

You may find that your finger nails and toe nails grow more slowly, or become hard, brittle or flaky. The shape or colour of your nails might also change. These changes are temporary and should improve after treatment, though it can take a few months.

Keeping your nails trimmed short and wearing gloves while doing jobs around the house can help protect your nails. Some research suggests that rubbing natural oils into your nails each day could help to protect them.

Watery eyes

Your eyes might produce more tears than normal. This isn’t common and won’t last long. If your eyes feel sore, inflamed or watery, let your doctor know – they may prescribe eye drops.

Changes to your mood

Some people say they feel down at certain times during their chemotherapy. This is natural and usually only lasts a short time, but some men find they still feel low after their treatment finishes.

If you’re feeling really low and finding it hard to deal with things, speak to your doctor or nurse. There are things that can help and there is support available.

Having children

Chemotherapy can affect your sperm and semen, which can be harmful during pregnancy. So it is important to wear a condom during sex if your partner is pregnant, or if there is a chance they could become pregnant. You should wear a condom during your treatment, and for four months after you have finished your chemotherapy.

You may not be able to have children naturally after chemotherapy. You may want to think about storing your sperm before your treatment so that you can use it later for fertility treatment. Ask your doctor or nurse about storing sperm.

References

Updated: November 2025 | Due for Review: November 2028