Cancer-related fatigue (extreme tiredness)

Learn more about coping with fatigue - extreme tiredness and exhaustion that doesn’t always go away with rest or sleep.

1. What is fatigue?

Fatigue is extreme tiredness and exhaustion. It doesn’t always go away with rest or sleep and may affect you physically and emotionally. It’s a very common side effect of breast cancer and its treatments, and may last for weeks, months or longer after your treatment has finished.

Everyone knows what it feels like to be tired sometimes but if you have cancer-related fatigue you may feel like you have very little energy. You may find it difficult to do simple everyday tasks and it may stop you from doing things you want to do. Everyone’s experience of cancer-related fatigue is different. Know your limits and don’t expect too much of yourself.

It can be difficult to describe fatigue and other people may not always understand how you are feeling. Reading this information may help family and friends understand fatigue more.

Breast cancer treatment

Most of the treatments used for breast cancer have side effects that can contribute to fatigue.


You may feel tired after surgery. This can be due to the stress on your body, any pain after surgery and the time it takes to heal. Having a general anaesthetic can also affect your energy levels. If you had treatment before surgery such as chemotherapy or targeted therapies you may still be feeling tired from this.


The side effects of may include a lowered resistance to infection, anaemia (too few red blood cells in the body) and altered eating patterns. These side effects can cause or worsen fatigue.


Travelling back and forth to the hospital for can make you feel increasingly tired and the treatment can cause fatigue because of the way it affects your body. This tiredness may start or get worse after radiotherapy has finished.

Hormone (endocrine) therapy and targeted (biological therapies)

and some types of may cause fatigue.

Other medicines

You may need to take other medicines alongside your main treatments, and these can also contribute to fatigue. For example, pain relief, anti-sickness drugs, sleeping tablets and antidepressants may make you feel very tired. Steroids are often used alongside chemotherapy, which can make you feel restless and may disrupt your sleep.

Emotional causes

Many people feel worried and anxious about their diagnosis and treatment. These feelings and emotions can make your fatigue worse. Find out more about managing anxiety and coping with depression.

Sleep disruption

If your sleep is disrupted by side effects, this can make fatigue worse.

Find out more about sleep disruption.

Other causes

If you experience fatigue see your GP, as it may not be related to your cancer or treatment. For example, fatigue can occur due to thyroid problems, heart conditions or diabetes.

3. Tips for managing your fatigue

  1. Tell your GP or nurse how you’re feeling. Your fatigue may have a treatable cause, for example anaemia, which can be treated with iron supplements.
  2. Try using a fatigue diary. This involves recording your level of fatigue every day from 1 (no fatigue) to 10 (extreme fatigue). This can help you think about how your treatment affects your energy levels so you can plan your day and make the most of the times when you have more energy. If you have finished treatment it can still be useful to keep a record of when you are more or less tired so you can plan any activities, especially those that require more energy.
  3. There is strong evidence that regular moderate exercise (such as walking, cycling or swimming) can help reduce fatigue.
  4. Plan your day to balance your activities and rest times. Try and get plenty of rest between your daily activities, but limit the number of naps you have. Keep naps to less than half an hour and avoid taking them in the late afternoon, so that you sleep at night.
  5. Use relaxation techniques to help you relax and regain energy. There are many good relaxation CDs or apps that can guide you through different techniques.
  6. Drink plenty of fluids (6–8 glasses a day) to keep hydrated. Being dehydrated can make you tired.
  7. Eating well can help improve your energy levels. Make the most of the times when your appetite is good and try to choose foods that give you energy over a period of time, like nuts and cereals. Sugary foods may give you a quick fix but won’t keep your energy levels up for very long.
  8. Try and accept offers of practical help from others where possible, for example help with household chores or getting to appointments. Often people want to help but don’t know what you need, so let them know.
  9. There is some evidence that being well supported may help to reduce fatigue. Think about the kind of support that would suit you – for example, you could join a local support group if there’s one in your area, or have some individual counselling.

Macmillan Cancer Support publishes an information booklet called Coping with fatigue, which you may find useful. Order it free from Macmillan's website or call 0808 808 00 00

4. Further support

Fatigue can be overwhelming and frustrating. Many people who experience fatigue find that others don’t understand how different it is to normal tiredness and the impact it can have.

If fatigue is having a big impact on your daily life, you don’t have to cope with this alone. You can join our online forum and talk to people who are in the same situation – they may be able to offer tips and support. You can also call our free helpline to talk through your concerns - please see below.

You might find it helpful to download Becca, our free app for people with breast cancer - also below. Becca provides strategies and tips to help you move forward after breast cancer treatment.

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Last reviewed in March 2019. The next planned review begins in February 2023.

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