Side-effects of cancer treatments

Remember not everyone experiences side-effects in the same way. The side-effects depend on the part of your body being treated. All of these effects are normal so try not to worry.

Your doctor or nurse will tell you what side-effects you can expect from your treatment. See our list below for futher information about various side-effects.


You can feel fatigued for many reasons: your cancer itself, the symptoms caused by your cancer or the treatment for that cancer. Fatigue can affect you physically and emotionally, and it can be very frustrating, as it does not go away with rest.

Fatigue can remain for up to six months after your treatment has finished.

There are some ways that can help to manage it, including:

  • support from family or friends (like getting them to do the shopping)
  • lots of rest
  • keeping a fatigue diary (to identify when your energy levels are highest, to plan your day better)
  • a balanced diet

Let your doctor or nurse know about your fatigue, and they'll be able to help with some symptoms. You can also read our Coping with Fatigue booklet.

Skin and nail changes

Some treatments can make your skin dry, discoloured or more sensitive to sunlight. They can also make your nails may grow more slowly and become more brittle and flaky - or change the shape and colour of your nails.

To protect yourself, you should:

  • Avoid the sun between 11am and 3pm
  • Wear a hat and long-sleeved shirt
  • Apply sunscreen SPF 15 or higher thirty minutes before you leave the house (and re-apply every two hours).
  • Don't use perfumed soaps or powders
  • Dry your skin by pat it gently with a soft cotton towel

If you develop a rash or any other skin changes, you should talk to your doctor immediately.

Hair loss (Alopecia)

Sometimes chemotherapy and certain drug therapies cause hair loss; some may thin the hair while others do not affect it at all. You may lose all body hair including your eyelashes and pubic hair, which can be very distressing.

Your doctor or nurse will let you know if the chemotherapy you are receiving causes hair loss. Your hair can begin to fall out within a few weeks of your first treatment and will begin to grow back a few weeks after your last treatment.

It is important to pick out a wig before your hair falls out so that a close match can be obtained. Some people find it beneficial to cut their hair very short before it falls out and to wear a hair net at night, as it can be very upsetting to wake up in the morning with a lot of hair on you pillow.

Not everyone will want a wig and there are other alternatives if required (scarves/turbans). It is important not to use chemical hair dyes or to perm your hair while you are on treatment. Avoid using hair dryers, curling tongs and curlers Pat your hair dry after washing and use a soft or baby brush.

If you find hair loss extremely distressing there is a method available to try to reduce the amount of hair loss. This is called scalp cooling. It works by cooling the head and reducing the blood flow to the scalp thus reducing the amount of drug reaching the hair follicles.

This treatment does not work for everyone can only be given in certain circumstances and is not available in every hospital. You can ask your doctor or nurse about scalp cooling.

For more information, visit our section on Hairloss and cancer treatment.

To find your local wig supplier please call our Cancer Nurseline Freephone 1800 200 700 and speak to one of our cancer nurses. The Cancer Nurseline is open Monday – Thursday 9am – 6pm and Friday 9am – 5pm.

Cancer Pain

Not everyone with cancer will experience pain. However, pain can be common during treatments and in the advanced stages of cancer, and sometimes after your treatment while you recover. If you have any other queries or concerns about pain, please speak to your GP or pain team or contact our Cancer Nurseline on 1800 200 700.

For more information on Cancer Pain, read our Factsheet.

Nausea and vomiting

Some drugs make you feel sick or get sick (although many people experience no sickness at all). Sickness depends on the drugs you're taking. You can feel sick from a few minutes to several hours after the chemotherapy treatment, and it may last for a few hours or, in rare cases, for several days.

If you are receiving a drug that causes sickness, your doctor will prescribe medication called anti-emetics to prevent this. You may receive them immediately before your treatment and in tablet form to take when you go home. Anti-emetics should prevent nausea and vomiting, so if you do experience either of these, tell your doctor - he or she may prescribe an alternative or combination anti-emetics.

There are other ways to minimise nausea:

  • Eat small amounts of food regularly
  • Avoid fatty foods
  • Avoid foods that make you feel sick
  • Avoid taking a lot of fluid just before you eat
  • Eat or drink ginger or peppermint
  • Take plenty of fluid in small amounts throughout the day

Changes to blood cells

Chemotherapy can affect your bone marrow, which is responsible for making blood cells.


White blood cells fight infection, so when their number is low (neutropenia) you are more prone to picking up infections. To avoid infections, you should:

  • Stay away from people with colds or other infections, such as chickenpox, shingles or measles.
  • Take extra care with your personal hygiene, making sure to wash your hands after using the bathroom.
  • Eat a well balanced diet - don't eat foods from take aways or fast food restaurants and wash your fruits and vegetables thoroughly

You will have regular blood tests taken to count your white blood cells. Sometimes your doctor will prescribe a white blood cell growth factor called GCSF, which is injected under the skin.

Contact your doctor or the Oncology Unit straight away if you have a sore throat, cough, feel pain passing urine, experience redness or swelling (e.g., at a catheter site) or have a temperature of 38ºC or over.


Anaemia occurs when the red blood cells that carry oxygen around your body are reduced.

You may feel very lethargic, breathless, dizzy and light-headed. You will have regular blood tests taken to measure your red blood cell count (haemoglobin).

You may need a blood transfusion or your doctor may prescribe an erythropoietin injection to stimulate red blood cell production.


Platelets are another blood cell that is produced in the bone marrow. They help to stop bleeding by clotting the blood.

If your platelet count is low (thrombocytopenia) you will be more prone to bruising and bleeding.

Tell your doctor if you have unusual or prolonged bleeding or if you notice a pinpoint-like rash on your body. Your platelet count will be measured regularly and you may need a platelet transfusion.

Sore Mouth

The cells lining your mouth can be affected by your treatment, causing a sore mouth. Take special care of your oral hygiene. Your doctor will prescribe mouthwashes, which should be used regularly.

You should use a soft toothbrush, remove and clean dentures regularly, drink plenty of fluid to keep your mouth moist, keep your lips moist by applying petroleum jelly and avoid very hot or acidic drinks.

If you develop an ulcer, inform your doctor as this can become infected. Chemotherapy can also cause your sense of taste to change temporarily during your treatment.

Constipation and diarrhoea

Chemotherapy or radiotherapy can also cause a change in your bowel habits. Some may cause diarrhoea (passing watery bowel motions more than twice a day).

If you have diarrhoea drink plenty of fluids, avoid a high-fibre diet and contact your doctor if it persists. If you have more than 4-6 episodes of diarrhoea a day contact your nurse or doctor at the hospital - they may be able to prescribe a medication.

Chemotherapy may also slow down the movement of the bowel, making it difficult to pass a bowel motion, a condition known as constipation.

If you experience constipation, drink lots of fluids, eat a high-fibre diet and tell your doctor if it persists, as you may need to go on medication (laxatives) to help relieve it.

Sex and fertility

Some people go through chemotherapy with no change to their sex lives; others find that their sex lives are temporarily or permanently changed in some way due to their treatment.

Any changes that occur are usually temporary (e.g., fatigue and anxiety can affect your sex life) but these pass following the completion of treatment.

There is no medical reason not to have sex while on chemotherapy. However you should use condoms while on treatment. Do not presume that you are infertile while on chemotherapy; you should use a reliable method of contraception throughout your treatment and for some time afterwards.

Female fertility

Some drugs used to treat cancer have no effect on your fertility; others can affect your ovaries. Your periods may become irregular or stop during treatment or for a few months afterwards. You may get some symptoms of menopause, e.g., hot flushes. However, your periods may return to normal after a few months. In general the younger you are, the more likely your periods are to return to normal and you will still be able to have children. The nearer you are to menopause, the more likely chemotherapy is to stop your periods permanently. When you are finished treatment, there are blood tests that can be done to show if you are fertile or not.

Male fertility

For men, like women, the cancer itself or the treatment can cause infertility; this may be temporary or permanent. Talk to your doctor if you have any concerns.
Egg/sperm freezing sub-heading of sex and fertility.

If there is a risk your chemotherapy will cause long-term infertility, you may have the option of freezing your eggs/sperm before treatment begins. The Human Assisted Reproduction Ireland (HARI) unit at the Rotunda Hospital, Dublin provides such a service. You must be referred there by your oncologist, be over 16 and be able to give informed consent. This procedure is not suitable for everyone so it's essential you talk to your oncologist before you start your treatment.

Coping with infertility

You may feel devastated if you are told that you can no longer have children. It can take a while to sort out your emotions and be able to talk about them. It may be helpful to talk to your partner or friend about how you are feeling. There is no right or wrong way to react. However, the full impact may only hit you when your treatment has finished.

Pregnancy and cancer

Avoid pregnancy during chemotherapy, in case the drugs harm your baby. Many doctors believe it is better not to get pregnant for 2 years after your chemotherapy ends. There can also be a risk of miscarriage, or birth defects in children. Speak to your doctor if you have any worries.

If you became pregnant before your cancer was diagnosed it is important to discuss all your options with your doctor.

It may be possible to delay chemotherapy until later in your pregnancy or until your baby is born.

In some cases, it is also possible to have chemotherapy and deliver a healthy baby. However, depending on your situation you may not have a choice.


Lymphoedema (lim-fo-dee-ma) is a long-term (chronic) swelling caused by a build-up of fluid in the body’s tissues. This happens when the lymphatic system, which normally drains fluid away, is unable to work properly.

Sometimes cancer or cancer treatments can cause lymphoedema.

Find out more information about lymphoedema.

Rare side effects

Some chemotherapy drugs can cause damage to your kidneys. To prevent this, your doctor may give you fluids before and after your treatment. You should also drink as much fluid as possible while at home – about 1.5 litres per day.

Tell your doctor if you experience these symptoms - he or she can give you a medication to alleviate them. Alternatively, your treatment may have to be changed slightly.

Some chemotherapy drugs can cause a continuous sound (buzzing or ringing) in your ears called tinnitus. Mention this to your doctor, as some changes will have to be made to your treatment.

Brachytherapy side effects

You might feel sore where the applicators were placed or notice some bruising. If you have brachytherapy to your prostate, there may be some blood in your urine.

If you are unable to pass urine even though your bladder is full, contact the hospital or your GP.

This happens in about one in 10 men and you may need a catheter put in again to let things settle down.