Fatigue
Fatigue is extreme tiredness or exhaustion that doesn’t go away with rest. It’s a common symptom of leukaemia and other blood cancers. Find out more about fatigue, and when to seek help.
Summary
- Fatigue is a very common symptom. Most people with fatigue do not have leukaemia.
- But persistent fatigue can be a symptom of leukaemia or other types of blood cancer.
- If you have fatigue that lasts for more than 4 weeks, make an appointment with your GP and ask for a blood test.
About fatigue
Fatigue is the most common symptom of leukaemia and other types of blood cancer in adults. But it is a very common symptom generally, and it can be caused by a whole range of different conditions. In fact, fatigue is one of the most frequent reasons for a person to visit their GP.
Around 1 in 3 people with leukaemia have fatigue as a symptom at diagnosis. Around 2 in 3 do not.
Fatigue can also be a side effect of treatment. We’re developing separate information on coping with fatigue for people who already have a diagnosis.
Like all symptoms of leukaemia, having fatigue does not mean you definitely have leukaemia. But if you’re worried about your symptoms, it’s a good idea to see your GP.
Overall, fewer than 2 in 100 people who visit their GP with fatigue have cancer. More than 98 in 100 do not have cancer. These numbers vary a bit depending on your age and sex. But the important thing to remember is that most people who have fatigue do not have cancer.
What is fatigue?
Everyone feels tired sometimes. It’s a normal response to a long day, a bad night’s sleep or physical exercise.
Fatigue is not the same as normal tiredness. Fatigue is tiredness or exhaustion that:
- Is not proportional to exercise or activity
- Doesn’t get better after sleep or rest
- Interferes with your daily life
Fatigue can be physical, mental or emotional. If you have fatigue, you might feel exhausted, worn out or physically weak. You might find it hard to focus or concentrate, or get tired sooner than you would usually. You might feel listless or sleepy. It can make it hard to do everyday things that other people take for granted.
People often say it’s hard for someone without fatigue to understand how it feels. They sometimes describe it as having no energy or running on empty.
Children with fatigue might seem floppy or lethargic, or lose interest in doing things they normally enjoy. They might be quiet, sleepy, irritable or clingy, or just not seem themselves. They might look pale with dark shadows under their eyes.
Why do people with blood cancer get fatigue?
The main cause of fatigue in people with blood cancer is a low level of red blood cells. This is called anaemia.
Red blood cells carry oxygen around your body. They grow and develop in your bone marrow.
If you have blood cancer, your bone marrow can get filled with cancer cells. This stops it making enough healthy blood cells, including red blood cells.
If you do not have enough red blood cells, your blood cannot carry enough oxygen around your body. This can make you feel tired easily.
Other signs of anaemia
- Looking pale. If you have black or brown skin, this may be easier to see on your palms, gums or the inside of your lower eyelids.
- Feeling more breathless than usual. Or getting breathless after mild exercise or activity.
- Feeling dizzy.
- An irregular, fast, pounding or fluttering heartbeat.
There are also some other factors that might contribute to fatigue.
- Cancer cells use energy, so if you have blood cancer, your body is using more energy than usual. This might make you tired.
- Cancer can activate an inflammatory response in your body. This helps your immune system fight the cancer, but it can also cause fatigue.
- Cancer cells can make chemicals that affect the balance of hormones in your body. This can affect your metabolism and your sleep patterns. This can lead to fatigue.
Fatigue can also be a side effect of treatment for leukaemia and other blood cancers. We’re developing separate information on coping with fatigue for people who already have a diagnosis.
What else can cause fatigue?
Fatigue can be caused by lots of things. Most people who get it do not have leukaemia.
Other things that can cause fatigue include:
- A change in your usual sleep, diet, exercise or work patterns
- Short-term illnesses like infections
- Depression, anxiety or stress
- Bereavement
- Sleep problems
- Chronic fatigue syndrome
- Fibromyalgia
- Diabetes
- Underactive thyroid gland
- Autoimmune conditions
- Low vitamin or mineral levels
- Some medicines
- Pregnancy or breastfeeding
- Other types of cancer
When to seek help
If you have fatigue that lasts for more than 4 weeks, make an appointment with your GP and ask for a blood test.
Nearly 4 in 10 people with leukaemia wait 3 months or more before contacting a GP about their symptoms.
Some signs that you should contact your GP include tiredness or exhaustion that:
- Lasts for 4 weeks or more. Less if you have other symptoms too.
- Is accompanied by other symptoms.
- Is getting worse.
- Is not related to exercise or activity levels.
- Does not get better after rest or sleep.
- Has no obvious cause.
- Stops you doing things you want or need to do.
If you have ongoing fatigue and your GP can’t identify a cause, they should consider an urgent blood test. If they don’t offer you a blood test, ask for one. They might refer you for other tests too.
If you are struggling to get help
Nearly 3 in 10 people with leukaemia have to speak to their GP three or more times before getting a diagnosis.
There may be many possible explanations for your symptoms for a GP to consider.
If you have to go back to your GP three or more times about the same symptom, remind them about Jess’ rule. This encourages GPs to ‘reflect, review and rethink’, particularly if:
- You still have the symptoms
- They have got worse
- They are unexplained
Take a look at our Spot Leukaemia campaign to find out what we’re doing to help the public and GPs spot the signs of leukaemia sooner.
Sources
Sources we used to develop this information
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Page last reviewed: 10 September 2026
Updated September 2026
Next review due: 30 September 2029
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