Fatigue and breast cancer treatment

If treatment for early or metastatic breast cancer is making you extremely tired, you’re not alone. Extreme tiredness, or fatigue, is one of the most common and distressing side effects of breast cancer treatment.

Depending on its cause, fatigue can last from 3 to 12 months or even longer after your surgery, chemotherapy or radiotherapy has finished. When you are living with metastatic breast cancer, fatigue is very common.

We share tips to help you cope. Your treating team can also suggest ways to reduce or manage it.

Signs of fatigue

Everyone's experience of fatigue is different. Many people describe fatigue as an almost total lack of energy. It’s different from normal tiredness and you can feel fatigued all the time, even after plenty of sleep.

This can make it difficult to do daily tasks and activities.

Signs of fatigue include:

• less energy or you need to rest more often
• general weakness and a heavy feeling in your arms and legs
• trouble with concentration, attention or short-term memory
• less motivation or less interest in your usual activities
• problems sleeping, or often feeling over-tired
• not feeling refreshed after sleep or resting
• feeling more emotional, irritable or depressed
• finding it hard to finish things.

Causes of fatigue

Experts don’t know exactly what causes fatigue with cancer treatment. It could be a mix of:

• treatment side effects
• coping with pain
• side effects of other medications, such as drugs to prevent nausea or reduce pain.
• anaemia (lack of red blood cells)
• stress, anxiety, depression 
• mental fatigue
• travelling for treatment
• sleep difficulties

Fatigue after surgery

You may feel tired after surgery. This can be due:

• the anaesthetic, which affects energy levels
• the stress on your body from the surgery itself
• the healing process, which takes a lot of energy
• pain after surgery.

If you have treatment before surgery (‘neoadjuvant therapy’) you may also be recovering from this.

Chemotherapy and fatigue

Chemotherapy can have several side effects that add to fatigue, such as:

• a lower resistance to infection
• anaemia
• changes to your normal eating patterns.

Fatigue is often worst in the week or so after chemotherapy. It usually improves before the next dose.

After your first chemotherapy cycle, you’ll have a better idea of the pattern. That helps you plan your time in between cycles.

Apart from the chemotherapy drug itself, other causes of fatigue during chemotherapy treatment include:

• medications such as anti-nausea or pain medication
• insomnia, if the chemotherapy causes menopausal symptoms such as hot flushes or night sweats
• anxiety
• other medical conditions you may have, such as heart or thyroid problems.

You will have blood tests regularly while you are having chemotherapy to check your blood cell count. If a low blood cell count becomes a problem, your doctor may:

• recommend an injection called filgrastim or pegfilgrastim, or
• decrease the dose of your chemotherapy

Read about other common Chemotherapy side effects.

Radiotherapy and fatigue

Radiotherapy treatment itself can cause fatigue because of the way it affects your body. It is normal to feel more tired as radiotherapy progresses.

Travelling to and from radiotherapy can also be tiring.

This feeling can last for months after radiotherapy finishes, especially if you've had chemotherapy as well.

Read about Common radiotherapy side effects and Rare radiotherapy side effects.

Hormone-blocking therapy and fatigue

If your breast cancer is hormone-receptor positive, you will probably be advised to take hormone-blocking tablets.

This medication may cause menopausal symptoms, which can add to feelings of fatigue and tiredness.

For information on other side effects of hormone-blocking therapy, go to Menopausal symptoms and breast cancer treatment.

Tips to help manage fatigue

You can make small changes to reduce fatigue and make the most of the energy you have. It's important to manage your own expectations, though. You've been through a lot physically and mentally, regardless of which treatments you've had. Recognise that it will take time to recover fully, and this is okay. Everyone recovers at a different pace.

Try and keep active…

Resting is a normal response to fatigue. But it’s important to find the right balance between rest and regular activity.

Include gentle exercise, such as walking, for 30 minutes every day. Research shows that even light exercise can reduce fatigue caused by treatments.

Exercise can also reduce your chance of weight gain. Talk to your doctor or breast care nurse about the best types of exercise for you.

Understand how to use exercise to reduce fatigue at healthy lifestyles when diagnosed with breast cancer.

Don't overdo it on days when you feel good.

… but balance activity with rest

• Plan to rest on the days when you know your side effects might be at their worst.
• Rest during the day between activities but keep naps short so you can still sleep at night.
• Take time to relax and read, listen to music or watch TV without worrying about what you 'should' be doing.
• Plan only one activity each day to pace yourself.
• On days when you don't have much energy, save it for the things you enjoy most.
• Reduce stress with relaxation exercises such as mindfulness, yoga, tai chi, or massage.
• After you finish treatment, give your body time to recover. Return slowly to your previous level of activity instead of stepping straight back into old routines.

Look after your nutrition

• Eat as well as you can and aim to keep your ideal weight. A dietitian can develop a plan for a well-balanced diet.
• Take any supplements your doctor or dietitian recommend, but always check with them before you take any new supplements.
• Drink plenty of water to keep hydrated.
• Limit coffee and other drinks with caffeine, particularly after 3pm.
• Don't skip meals.

Ask for help and support

Try to organise practical help at home before you start treatment, such as help with childcare, housework or making meals.

Find out if you are eligible for home help from your local council.

Accept offers of help from those around you.

Talk to your employer about changes you can make when your fatigue is at its worst. You may be able to work from home, take leave or temporarily reduce your hours.

Discuss how you feel with a support group or counsellor. Find a support group near you on BCNA's Service Finder or call the Cancer Council on 13 11 20.

Join BCNA’s Online Network to connect with others affected by breast cancer.

Talk to your treatment team about ways to reduce or manage fatigue.

Fatigue is also connected to chemo brain or brain fog. Find ways to reduce the impact and manage daily tasks at Brain fog or cognitive impairment.