Breathlessness
Unexplained breathlessness can be a symptom of leukaemia or other types of cancer, including other blood cancers. Find out why this is, and when to seek help.
Summary
- Breathlessness is a very common symptom. It can be caused by many conditions.
- Most people with breathlessness do not have leukaemia. But unexplained breathlessness can be a symptom of leukaemia or other types of blood cancer.
- If you have breathlessness that lasts for more than a few weeks or is getting worse, make an appointment with your GP.
About breathlessness
Breathlessness is one of the most common symptoms of leukaemia and other types of blood cancer in adults. But it is also extremely common in many other conditions. Most people with breathlessness do not have cancer.
Breathlessness is a feeling of discomfort when you breathe. It may be mild, moderate or severe. It can be hard to describe.
- It might feel like more effort than usual to breathe
- It can be a feeling of tightness in your chest
- You might feel that you need more air even after breathing in
- Your breathing might feel faster or shallower than usual
Like all symptoms of leukaemia, breathlessness can be caused by many things. Experiencing breathlessness does not mean you definitely have leukaemia. But if you’re worried about your symptoms, it’s a good idea to see your GP.
Why do people with blood cancer get breathless?
The main cause of breathlessness 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 breathless.
Other signs of anaemia
- Looking pale. If you have black or brown skin, this may be easier to see on your palms, gums or inside your lower eyelids.
- Feeling tired or exhausted.
- Feeling dizzy.
- An irregular, fast, pounding or fluttering heartbeat.
Other possible causes of breathlessness in people with blood cancer include:
- Swollen lymph nodes in the chest. These can press on your airways and make it harder for air to flow in and out of your lungs.
- An extremely high white blood cell count. This can make your blood become thicker than usual, which can stop your tissues getting enough oxygen, This can make you feel breathless. This condition is very rare.
What else can cause breathlessness?
Breathlessness can be caused by lots of things. Most people who get it do not have leukaemia.
Other things that can cause breathlessness include:
When to seek help
Call 999 or go to A&E straight away if you are having serious difficulty breathing, you are gasping, choking or finding it hard to speak.
If you’re feeling breathless and you have a painful or swollen leg, palpitations or you’re coughing up blood, visit NHS 111 online or call 111.
If you have breathlessness that lasts for more than a few weeks, make an appointment with your GP.
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 breathlessness that:
- Feels out of proportion to your level of activity. It might start after only mild exercise. Or you might notice you can’t do as much as you used to without feeling breathless.
- Is accompanied by other symptoms.
- Is getting worse.
- Lasts more than 3 weeks. Less if you have other symptoms too.
If you have breathlessness and your GP can’t identify a cause, they should consider an urgent blood test or refer you for specialist assessment. If they don’t, ask them to.
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
We used an AI tool to help identify relevant evidence sources for this webpage, such as scientific journals and clinical guidelines. A human checked the reliability of these sources.
Sources we used to develop this information
Black GB, Boswell L, Harris J, Whitaker KL. What causes delays in diagnosing blood cancers? A rapid review of the evidence. Primary Health Care Research & Development. 2023 Jan;24:e26. DOI: https://doi.org/10.1017/S1463423623000129
Berliner D, Schneider N, Welte T, Bauersachs J. The differential diagnosis of dyspnea. Deutsches Ärzteblatt International. 2016 Dec 9;113(49):834. DOI: https://doi.org/10.3238/arztebl.2016.0834
Clarke RT, Jones CH, Mitchell CD, Thompson MJ. ‘Shouting from the roof tops’: a qualitative study of how children with leukaemia are diagnosed in primary care. BMJ Open. 2014 Feb;4(2):e004640. DOI: https://doi.org/10.1136/bmjopen-2013-004640
Clarke RT, Van den Bruel A, Bankhead C, Mitchell CD, Phillips B, Thompson MJ. Clinical presentation of childhood leukaemia: a systematic review and meta-analysis. Archives of Disease in Childhood. 2016 Oct 1;101(10):894-901. DOI: https://doi.org/10.1136/archdischild-2016-311251
Howell DA, Smith AG, Jack A, Patmore R, Macleod U, Mironska E, Roman E. Time-to-diagnosis and symptoms of myeloma, lymphomas and leukaemias: a report from the Haematological Malignancy Research Network. BMC Blood Disorders. 2013 Oct 31;13(1):9. DOI https://doi.org/10.1186/2052-1839-13-9
Macaron W, Sargsyan Z, Short NJ. Hyperleukocytosis and leukostasis in acute and chronic leukemias. Leukemia & Lymphoma. 2022 Jul 3;63(8):1780-91. DOI: https://doi.org/10.1080/10428194.2022.2056178
National Institute for Health and Care Excellence (NICE). Clinical Knowledge Summary: Haematological cancers - recognition and referral. Revised 2025. Available at: https://cks.nice.org.uk/topics/haematological-cancers-recognition-referral/ [Accessed May 2026]
National Institute for Health and Care Excellence (NICE). Clinical Knowledge Summary: Tiredness/fatigue in adults. Revised June 2025. Available at: https://cks.nice.org.uk/topics/tiredness-fatigue-in-adults/ [Accessed May 2026]
National Institute for Health and Care Excellence (NICE). Suspected cancer: recognition and referral. NICE guideline NG12. 23 June 2015; updated 25 April 2026. Available at: https://www.nice.org.uk/guidance/ng12 [Accessed May 2026]
NHS cancer programme: faster diagnosis framework. November 2022. Available at: https://www.england.nhs.uk/publication/cancer-programme-faster-diagnosis-framework/ [Accessed May 2026]
NHS England. National Cancer Patient Experience Survey 2024. Available at: https://www.ncpes.co.uk/latest-national-results/ [Accessed May 2026]
NHS Scotland. Scottish referral guidelines (SRGs) for suspected cancer: Haematological cancers. Available at: https://www.rightdecisions.scot.nhs.uk/scottish-referral-guidelines-srgs-for-suspected-cancer/haematological-cancers/ [Accessed May 2026]
Parshall MB, Schwartzstein RM, Adams L, Banzett RB, Manning HL, Bourbeau J, Calverley PM, Gift AG, Harver A, Lareau SC, Mahler DA. An official American Thoracic Society statement: update on the mechanisms, assessment, and management of dyspnea. American Journal of Respiratory and Critical Care Medicine. 2012 Feb;185(4):435-52. DOI: https://doi.org/10.1164/rccm.201111-2042ST
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Page last reviewed: 10 September 2026
Updated September 2026
Next review due: 30 September 2029
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