Chemotherapy side effects

Learn about the possible side effects of chemotherapy for breast cancer - which are usually temporary - and how they can be managed or controlled.

1. Side effects of chemotherapy for breast cancer

Like any treatment, can cause side effects. Everyone reacts differently to drugs and some people have more side effects than others. These side effects can usually be managed and those described here will not affect everyone.

Your treatment team will give you information about the drugs you are having, details of any side effects they may cause and how these can be controlled or managed.

Before starting chemotherapy you should be given a 24-hour contact number or told who to contact if you feel unwell at any time during your treatment, including at night or at the weekends.

Between each cycle of chemotherapy, you’ll have an assessment to see how you’re feeling and whether you’ve had any side effects.

If you are concerned about any side effects, regardless of whether they are listed here, talk to your treatment team as soon as possible.

2. Effects on the blood

Chemotherapy can temporarily affect the number of blood cells in the body.

You’ll have regular blood tests to check your blood count. Blood is made up of red cells, white cells and platelets. If the number of blood cells is too low, your next treatment cycle may be delayed or the dose of chemotherapy reduced.

Risk of infection

When the white blood cells fall below a certain level, it’s known as neutropenia. Not having enough white blood cells can increase the risk of getting an infection.

Signs of an infection

Your treatment team may give you guidelines to follow for reporting signs of an infection. But generally you should contact your hospital immediately if you experience any of the following:  

  • A high temperature (over 37.5°C) or low temperature (under 36°C), or whatever your treatment team has advised  
  • Suddenly feeling unwell, even with a normal temperature  
  • Symptoms of an infection, for example a sore throat, a cough, a need to pass urine frequently or feeling cold or shivery 

Before starting chemotherapy, your treatment team should give you a 24-hour contact number or tell you how to get emergency care. You may need antibiotics.

Sometimes your doctor may recommend injections of drugs called growth factors. This helps the body make more white blood cells to reduce your risk of infection.


Having too few red blood cells is called anaemia. If you feel particularly tired, breathless or dizzy, let your treatment team know.

Bruising and bleeding

Chemotherapy can reduce the number of platelets, which help the blood to clot. You may bruise more easily, have nosebleeds or your gums may bleed when you brush your teeth. Tell your treatment team if you have any of these symptoms.

Reducing your risk of infection and bleeding

You can help reduce the risk of infection and bleeding by:

  • Regularly washing and drying your hands thoroughly
  • Cleaning any cuts and grazes and cover with a dressing or plaster
  • Avoiding people who are unwell or may be infectious
  • Eating as healthily as possible, and following any advice about food and drink given to you by your hospital
  • Drinking plenty of fluids
  • Storing and cooking food correctly

3. Blood clots

People with breast cancer have a higher risk of blood clots. Their risk is higher because of the cancer itself and some treatments for breast cancer. If the cancer has spread to other parts of the body (secondary breast cancer), this also increases the risk.

Having chemotherapy increases the risk of blood clots such as deep vein thrombosis (DVT).

People with a DVT are at risk of developing a pulmonary embolism (PE). This is when part of the blood clot breaks away and travels to the lung.

Blood clots can be harmful but are treatable so it’s important to report symptoms as soon as possible.

Blood clot symptoms

If you have any of the following symptoms, contact your treatment team or go to your local A&E department immediately:

  • Pain, redness/discolouration, heat and swelling of the arm or leg
  • Swelling, redness or tenderness where a central line is inserted to give chemotherapy - for example in the arm, chest area or up into the neck
  • Shortness of breath
  • Pain or tightness in the chest
  • Unexplained cough or coughing up blood

Find out more about blood clots.

4. Hair loss

For some people, hair loss can be one of the most distressing side effects of chemotherapy. The likelihood of losing your hair depends on the type and amount of chemotherapy drugs you’re given. Not all chemotherapy drugs cause complete hair loss. Some cause thinning while others may not affect the hair very much at all.

The purple bookmarked page below contains more information for you about hair loss, scalp cooling, wigs and looking after your hair.

5. Feeling sick (nausea) and being sick (vomiting)

You may feel sick or be sick after chemotherapy. This will depend on the type and dose of drugs you’re having. But this can usually be controlled.

You may start feeling sick straight after chemotherapy, a few hours after or up to several days later. For some people it may last for a few hours and for others it can continue for several days.

People who are very anxious or prone to travel sickness or morning sickness in pregnancy may be more likely to actually be sick.

You’ll be given anti-sickness medication, as tablets or into a vein, before each cycle of chemotherapy. You’ll also be given anti-sickness tablets to take at home.

Several types of anti-sickness drugs are available. You may need to take a combination of drugs to relieve your symptoms. This may include taking a low dose of steroids for a short time. If you keep feeling sick or are being sick, let someone in your treatment team know.

Contact your hospital if you keep being sick and have difficulty keeping fluids down, even if it happens at the weekend or during the night.

6. Extreme tiredness

Cancer-related fatigue is extreme tiredness that doesn’t go away with rest or sleep. It’s a very common side effect of breast cancer treatment and may affect you physically and emotionally.

Tell your treatment team if you are suffering with fatigue. They can assess you and offer advice on how to manage your energy levels.

Find out more about fatigue.

7. Skin reactions

Some chemotherapy drugs can make your skin dry or more sensitive. They can also cause rashes. If you develop a rash tell your treatment team as soon as possible.

Some chemotherapy drugs can cause a skin reaction called hand-foot syndrome, often called Palmar-Plantar syndrome. It usually affects the palms of the hands and soles of the feet, but you may also have symptoms in other areas such as the skin on the knees or elbows.

Ask your treatment team if they recommend any particular creams for your skin before using anything on it yourself.

8. Nail changes

Chemotherapy may cause changes to the appearance of your nails on your fingers and toes. This can be a change in the nail colour or texture, such as ridges forming. Nails can become more brittle and cracked. Occasionally the nail may lift off the nail bed and fall out, but nails will grow back.

As you’re more at risk of infection while having chemotherapy, it’s important to report any signs of infection such as redness, heat, swelling or pain in or under your fingernails and toenails to your treatment team.

To help protect your nails:

  • Hand cream will help moisturise your hands, feet and nails
  • Use gloves for household chores to protect your nails
  • If your toenails are affected, avoid tight-fitting shoes
  • Don’t wear false nails during chemotherapy as these can lead to infection or mask the signs of it
  • Avoid nail varnish as it tends to dry the nails out more, or you could try a water-based version as this is less harsh

9. Numbness and tingling in hands or feet

People having chemotherapy may have pain, numbness or tingling in their hands and feet. This is due to the effect of some chemotherapy drugs on the nerves and is known as peripheral neuropathy

If you have tingling or numbness (such as difficulty doing up buttons, or difficulty feeling the difference between hot and cold water with your fingertips), mention this to your treatment team so they can monitor your symptoms. 

10. Sore mouth

Chemotherapy may affect your mouth in a number of ways. It can cause:

  • Sore mouth and ulcers
  • Dry mouth, which can also increase the risk of tooth decay
  • Infection
  • Bleeding gums

You’ll usually be given mouthwash to reduce the risk of a sore mouth developing. If you do get a mouth infection your specialist or chemotherapy nurse can advise you about different mouthwashes or suitable medicine.

It’s advisable to see your dentist for a check-up before chemotherapy begins, and to avoid dental treatment during chemotherapy if possible. If you have any mouth problems let your chemotherapy nurse or treatment team know as soon as possible.

11. Taste changes

Some people notice that their taste changes while having chemotherapy. Some food may taste different, for example more salty, bitter or metallic. You may no longer enjoy some foods you used to enjoy.

If this is the case speak to your treatment team, they may be able to suggest ways of managing this. Your taste should return to normal once your treatment has finished.

You can read tips if you experience taste changes on our diet during breast cancer treatment page.

12. Effects on your digestive system

Chemotherapy can affect your digestive system in different ways. Some people get constipated, other people have diarrhoea. Your hospital will have its own guidelines, but if you have four or more episodes of diarrhoea within 24 hours contact you GP or treatment team. Drink plenty of fluids to avoid dehydration.

Some chemotherapy drugs can make indigestion more likely. Some may also cause heartburn, which is a burning feeling in the lower chest.

Let your chemotherapy team know if you have any of these side effects. They can prescribe medication to help and can give you information about diet. You can also be referred to a dietitian if necessary.

13. Effects on your concentration

Some people find treatment affects their ability to concentrate and makes them more forgetful.

This is sometimes called ‘chemo brain’ or ‘chemo fog’, but your treatment team may call it cognitive impairment. It usually improves over time after treatment has finished, but for some people it can continue for longer.

14. Pain at the injection site

Pain, redness, discolouration or swelling can occur where the needle has been inserted or anywhere along the vein.

Tell your chemotherapy nurse immediately if you have pain, stinging or a burning sensation around the cannula (small plastic tube) while the drug is being given.

15. Menopausal symptoms

Some women have menopausal symptoms. This is because chemotherapy affects the ovaries, which produce oestrogen.

If you have not yet reached the menopause, your periods may stop or become irregular during chemotherapy. Whether your periods return will depend on the type of drugs used, the dose given and your age.

Even if you stop having periods and experience menopausal symptoms, you may still be fertile and could become pregnant. Your specialist will usually recommend barrier methods of contraception, such as condoms.

You can talk to your treatment team about ways of coping with menopausal symptoms.

16. Effects on fertility

Chemotherapy causes changes in the ovaries, which can affect your ability to become pregnant. However, any effects will depend on the chemotherapy drugs you are having or have had in the past, and your age. 

Some women stop having periods (amenorrhoea) during chemotherapy, although this may be temporary. Women aged around 40 and above are less likely to have their periods return after completing chemotherapy than women under this age.

If you’re concerned about your fertility, talk to your treatment team before treatment begins.

Find out more about how breast cancer treatment can affect fertility.

17. Long-term side effects

Most chemotherapy side effects are temporary and disappear once your treatment has finished.

For some people side effects can last longer or may develop months or years after chemotherapy has finished.

Some chemotherapy drugs can cause heart or lung problems, and some drugs increase the risk of getting another cancer in the future. These late effects are rare. Your specialist can talk to you about the benefits of treating your breast cancer with chemotherapy compared to the risk of these rare effects occurring.

18. Further support

Many people worry about the side effects they might get. But most side effects can be controlled. You should be told what side effects to report as well as details of who to contact, day or night, if you have any concerns or are unwell.

Your chemotherapy team and breast care nurse can help with any questions you have.

On our online forum, you can find people going through treatment at the same time as you on the chemotherapy monthly threads.

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This information was published in July 2021. We will revise it in July 2023.

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