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Chemotherapy - Side effects - Chemotherapy

Chemotherapy can cause unpleasant side effects, but many of these can be treated or prevented. Most of them will pass when your treatment stops.

It's difficult to predict what side effects you'll get.

There are many common side effects, but it's unlikely you'll have all of them.

The side effects of chemotherapy can be distressing, but most are not serious.

Urgent advice: Contact your care team immediately if you have:

  • a high temperature of 38 degrees Celsius or above
  • shivering
  • breathing difficulties
  • chest pain
  • flu symptoms - such as muscle aches and pain
  • bleeding gums or nose
  • bleeding from another part of the body that does not stop after applying pressure for 10 minutes
  • mouth ulcers that stop you eating or drinking
  • vomiting that continues despite taking anti-sickness medicine
  • 4 or more bouts of diarrhoea in a day


Tiredness (fatigue) is one of the most common side effects of chemotherapy.

You may feel generally tired a lot of the time or tire very easily during everyday tasks.

It can help to:

  • get plenty of rest
  • avoid doing tasks or activities that you do not feel up to
  • do light exercise to boost your energy levels, such as walking or yoga
  • ask your friends and family for help with everyday tasks

If you have a job, you may want to ask your employer for time off. They may also let you work part-time until your treatment has finished.

Contact your care team if you suddenly feel very tired and out of breath. This can be a sign of anaemia.

Feeling sick and vomiting

Many people having chemotherapy will have periods where they feel sick or vomit.

Your care team can give you anti-sickness medicine to reduce or prevent this.

This is available as:

  • tablets or capsules
  • injections or a drip into a vein
  • suppositories - capsules you put into your bottom
  • a skin patch

Side effects of anti-sickness medicines include constipation, indigestion, problems sleeping and headaches.

Tell your care team if your medicine does not help or causes too many side effects. There may be a different one that works better for you.

Hair loss

Hair loss is a common side effect of chemotherapy, but it doesn't happen to everyone. Ask your care team if it's likely to be a side effect of the medicines you're taking.

If you do lose hair, it usually starts within a few weeks of your first treatment session. If you lose lots of hair this typically happens within a month or 2.

It's most common to lose hair from your head. You can also lose it from other parts of your body, including your arms, legs and face.

The hair loss is almost always temporary. Your hair should start to grow back soon after your treatment has finished.

But sometimes the hair that grows back is a slightly different colour. It may be curlier or straighter than it used to be.

Coping with hair loss

Hair loss can be upsetting. Talk to your care team if you find losing your hair difficult to cope with.

They understand how distressing it can be and can support you and discuss your options with you.

Other options include headwear such as a headscarves.

Hair loss and cancer treatment -

Preventing hair loss

It may be possible to reduce the chances of hair loss by wearing a cold cap while you're having chemotherapy.

A cold cap looks like a bicycle helmet. It cools your scalp during a treatment session. This reduces blood flow to the scalp, reducing the amount of medicine that reaches it.

Whether you can use a cold cap depends on the type of cancer you have. Cold caps also work better with certain types of chemotherapy medicine.

Cold caps do not always work. Ask your care team whether a cold cap might help you.


Chemotherapy can reduce your body's ability to fight infection. This makes you more likely to pick up infections that could make you seriously ill.

It's a good idea to take precautions to protect yourself against infection.

For example:

You may need anĀ antibioticĀ to reduce your risk of developing an infection.


Chemotherapy lowers the amount of red blood cells, which carry oxygen around the body.

If your red blood cell count drops too low, you'll develop anaemia.

Symptoms of anaemia include:

  • tiredness and lack of energy - this can be more severe than the tiredness from chemotherapy
  • shortness of breath
  • noticeable heartbeats (heart palpitations)
  • a pale complexion

Contact your care team as soon as possible if you have any of these symptoms. You may need treatment to increase your number of red blood cells.

Preventing anaemia

Including a high amount of iron in your diet can help reduce your risk of anaemia. Iron helps the body make red blood cells.

Foods high in iron include:

  • meat - particularly liver
  • beans and nuts
  • dried fruit - such as dried apricots
  • wholegrains - such as brown rice
  • fortified breakfast cereals
  • dark-green leafy vegetables - such as watercress and curly kale

Bruising and bleeding

Chemotherapy can reduce the number of cells called platelets in your blood. These help stop severe bleeding when you cut or injure yourself.

If you have a low number of platelets, you may have:

  • skin that bruises easily
  • severe nosebleeds
  • bleeding gums

Tell your care team if you experience these problems. You may need treatment to increase the number of platelets in your blood.

Sore mouth

Sometimes chemotherapy can make the lining of the mouth sore and irritated. This is known as mucositis.

Symptoms tend to develop a few days after treatment starts and include:

  • the inside of your mouth feeling sore - as if you've burnt it by eating very hot food
  • mouth ulcers, which can become infected
  • discomfort when eating, drinking or talking
  • a dry mouth
  • reduced sense of taste
  • bad breath

Tell your care team if you have any of these problems. They may recommend painkillers or special mouthwashes that can help.

Avoiding spicy, salty or sharp foods can also help.

Mucositis usually clears up a few weeks after chemotherapy finishes.

Emotional issues

Having chemotherapy can be a frustrating, stressful and traumatic experience. It's natural to feel anxious and to wonder if your treatment will be successful.

Stress and anxiety can also increase your risk of getting depression.

Speak to your care team if you're struggling to cope emotionally. They can offer support and discuss possible treatment strategies.

Your care team will be a team of health professionals who will care for you during your treatment.

Joining a cancer support group to talk to other people in a similar situation. This can reduce feelings of isolation and stress.

Find a list of cancer support groups -

You can also phone the Irish Cancer Society Support Line on 1800 200 700 (freephone), Monday to Friday 9am to 5pm.

Loss of appetite

You may lose your appetite while you're having chemotherapy. You should try to drink plenty of fluids and eat what you can.

It may help to:

  • eat smaller meals more often instead of 3 large meals a day
  • eat healthy snacks regularly
  • eat light meals on the day of your treatment
  • sip drinks slowly through a straw, instead of drinking them straight from a glass

Tell your care team if you're worried about your diet or lack of appetite.

Skin and nail changes

Some chemotherapy medicines can cause temporary changes to your skin.

For example, it may become:

  • dry
  • slightly discoloured (this may be patchy)
  • more sensitive to sunlight
  • red and sore
  • itchy

Talk to your care team if you have any problems with your skin. They can tell you about creams that can help and how to protect your skin from the sun.

Chemotherapy can also make your nails brittle or flaky. White lines may develop across them. This should go back to normal after your treatment has finished.

Using moisturiser on your nails may help. You can use nail varnish to cover your nails during treatment if you like. But not quick-drying varnish or false nails.

Memory and concentration problems

Some people have problems with short-term memory, concentration and attention span during chemotherapy. You may find that routine tasks take much longer than usual.

It's unclear why this happens. But the symptoms usually improve once treatment is finished.

Things such as using lists, calendars and your mobile phone for reminders can help. Doing some mental exercises, eating well, and getting enough rest may also be useful.

Sleep problems

You may have difficulty falling asleep, or wake up in the middle of the night and cannot get back to sleep. This is known as insomnia.

The following may help to improve your sleep:

  • set regular times for going to bed and waking up
  • relax before bed time - try taking a warm bath or listening to calming music
  • use thick curtains or blinds, an eye mask and earplugs
  • avoid caffeine, nicotine, alcohol, heavy meals and exercise for a few hours before going to bed
  • avoid watching TV or using phones, tablets or computers shortly before going to bed

Contact your care team if this advice does not work, as you may need more treatment.

Sex and fertility issues

Many people find that they lose interest in sex during chemotherapy. This is usually temporary. Your sex drive should gradually return after your treatment has finished.

Some chemotherapy medicines can also reduce fertility in men and women. This is often temporary, but can be permanent in some cases.

Before starting treatment, ask your care team if it will affect your fertility. If you're at risk of infertility, they will discuss your options with you.

Women may be able to have their eggs frozen to be used later in IVF. Men may be able to have a sample of their sperm frozen so it can be used for artificial insemination at a later date.

You should avoid becoming pregnant or fathering a child during your treatment. This is because chemotherapy medicines could harm the baby. Use a barrier method of contraception, such as a condom.

Condoms -

Diarrhoea and constipation

You may have diarrhoea or constipation a few days after you begin chemotherapy.

Your care team can recommend suitable medicine and diet changes that can help.

Page last reviewed: 15 September 2021
Next review due: 15 September 2024