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Extreme tiredness (cancer-related fatigue)

Learn more about extreme tiredness (cancer-related fatigue) and how you can manage it if you’re living with primary or secondary breast cancer.

1. What is fatigue?

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

Cancer-related fatigue is also 1 of the most common symptoms in people with

Everyone knows what it feels like to be tired sometimes, but cancer-related fatigue is much more extreme. You may have very little energy and find it difficult to do simple everyday tasks, or be unable to do them entirely.  

Everyone’s experience of cancer-related fatigue is different. It’s important to pace yourself and do what feels best for you. Try not to be hard on yourself if you need to cancel plans or spend a day resting.  

You may be unable to work or find returning to work particularly challenging (see our information on work and breast cancer for support).

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

Fatigue information diagram

Breast cancer treatment

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


If you’ve had chemotherapy, the side effects might cause fatigue or make it worse.

Side effects that may cause fatigue can include a lowered resistance to infection, too few red blood cells in the body (anaemia) and changes to your eating patterns or diet.


Radiotherapy can cause fatigue, which can last for weeks or months after treatment has finished.

You may also feel tired from travelling to and from the hospital for treatment.  

If you had treatment before radiotherapy, such as surgery, chemotherapy or targeted therapies, you may still be feeling tired from this.

You may only start to feel fatigued, or feel more fatigued, once your radiotherapy treatment has finished.


You may feel fatigued 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.

Fatigue after surgery can sometimes last for a few weeks.

Hormone (endocrine) therapy and targeted therapy

Hormone therapy and some types of targeted therapy may cause fatigue.

Other medicines

Medicines you may be taking alongside your main treatments, such as pain relief, anti-sickness drugs, sleeping tablets and anti-depressants, can also make you feel very tired.

Steroids are often used alongside chemotherapy and can make you feel restless and disrupt your sleep.

Emotional causes

You might be feeling worried, anxious or upset about your diagnosis and treatment. Sometimes these feelings and emotions can make you feel very tired and make fatigue worse.

Find out more about managing anxiety and coping with breast cancer emotionally.  

Depression and low mood

It’s natural to feel low or depressed after being diagnosed with breast cancer. Low mood usually improves after a little while, but if it doesn’t you could have depression.

Depression is a common condition and symptoms include feeling continuously low, having no motivation or interest in things, and feeling hopeless or helpless. It can contribute to fatigue and make you feel very tired.

There are lots of ways to get support and you don’t have to deal with depression alone. If you think you may be depressed, it’s a good idea to speak to your GP or treatment team.

Find out more about coping with depression.

Trouble sleeping

Feeling worried, changes to your normal routine and treatment side effects can all make it harder to sleep well, making fatigue worse.

If you’re struggling to sleep at night, our information on trouble sleeping has a range of useful tips and information to help you sleep better.

Other causes

It’s important to speak to your GP or treatment team if you have fatigue as it may not be related to your cancer or treatment. They can also offer support to help you manage your fatigue.

If your fatigue is ongoing and does not improve, speak to your GP or treatment team.

3. Tips for managing your fatigue

See if there’s a treatable cause

Tell your breast care nurse, treatment team or GP how you’re feeling. Your fatigue may have a treatable cause, for example anaemia, which can often be treated with iron supplements.

Use 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.

Try to be active

Try to be physically active if you feel up to it. There is strong evidence that regular moderate exercise (such as walking, cycling, yoga or swimming) can help reduce fatigue.

Plan time to rest

Plan your day to balance your activities and rest times. Try to 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 it doesn’t disrupt your sleep at night.

Try relaxation techniques

Use relaxation techniques to help you relax and regain energy. There are many good relaxation apps, audio downloads or CDs that can guide you through different techniques.

The NHS has information and resources to help you sleep better.

Some people also find the Calm and Sleepio apps helpful. Sleepio is only available on the NHS in certain areas, or you can access it with a referral from Macmillan.

Stay hydrated

Drink plenty of fluids (6 to 8 glasses a day) to keep hydrated. Being dehydrated can make you tired. Limit the amount of alcohol you drink. Alcohol may help you get to sleep but it can also cause disrupted sleep.

Eat well

Try to eat well as this can improve your energy levels. Make the most of the times when you’re feeling hungry and try to choose foods that give you energy over a longer 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.

Accept offers of help

Try to accept offers of practical help from others where possible, for example help with household chores, looking after children or getting to appointments. Often people want to help but don’t know what you need, so let them know.

Seek support

There is some evidence that being well supported may help reduce fatigue. Think about the kind of support that would suit you – for example, you could join a local support group if there’s 1 in your area, or have some individual counselling.

Try complementary therapies

Some people find complementary therapies such as acupuncture, massage, meditation and mindfulness help them manage fatigue.

If you’d like to try complementary therapies, speak to your treatment team first. They may advise you to avoid certain therapies if there’s a chance they could affect how your treatment works.

CAM Cancer also has helpful information about fatigue and complementary therapies.

Try cognitive behavioural therapy (CBT)

CBT has been shown to help people living with cancer-related fatigue. It’s a type of talking therapy that can help you change how you think and behave to help you manage your problems.

Speak to your GP or treatment team if you’re interested in trying CBT.

4. Further support

Fatigue can be overwhelming and frustrating. You might find that others don’t understand how you feel, how different fatigue is from tiredness or the impact it can have.

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. You can also visit RESTORE, an online resource from Macmillan that aims to support people living with cancer-related fatigue.

If fatigue is having a big impact on your daily life, you don’t have to cope 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.

You may also find our Moving Forward courses helpful. If you’ve come to the end of your treatment, you’ll gain support from people with similar experiences and be equipped with the tools you need to move forward after primary breast cancer.

If you’re living with secondary breast cancer, you can find a range of helpful resources and support options through our Living with Secondary Breast Cancer service.

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

For more information about these support services, please see below.

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Quality assurance

Last reviewed in March 2024. The next planned review begins in March 2027.

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