What is leukaemia (leukemia)?

Leukaemia (sometimes spelt as leukemia) is a cancer of the blood cells. If you have leukaemia, your body makes some abnormal blood cells. These leukaemia cells behave differently from healthy blood cells.

Different types of leukaemia are named according to:

  • the type of blood cell which is affected
  • whether the leukaemia is acute (faster growing) or chronic (slower growing).

Acute myeloid leukaemia (AML)

Acute myeloid leukaemia (AML) is a rare cancer of blood cells. It affects a type of cell called myeloid cells. AML can cause symptoms very quickly and usually needs to be treated as soon as possible after diagnosis.

Acute lymphoblastic leukaemia (ALL)

Acute lymphoblastic leukaemia (ALL) is a rare cancer of white blood cells. It affects a type of cell called lymphocytes. ALL can cause symptoms very quickly and usually needs to be treated as soon as possible after diagnosis.

Chronic lymphocytic leukaemia (CLL)

Chronic lymphocytic leukaemia (CLL) is the most common type of leukaemia. It affects a type of cell called lymphocytes. It develops slowly and often causes no symptoms in the early stages.

Chronic myeloid leukaemia (CML)

Chronic myeloid leukaemia (CML) is a rare cancer of white blood cells. It affects a type of cell called myeloid cells. It usually develops very slowly. For most people, CML can be well controlled and they will live a normal lifespan.

Symptoms of leukaemia (leukemia)

Chronic leukaemias develop slowly and many people have no symptoms in the early stages. It may be discovered by chance after a routine blood test.

Acute leukaemias are more likely to cause symptoms that appear over a few weeks, and people often feel ill quite quickly.

We have more information about possible symptoms of symptoms of leukaemia.

Causes of leukaemia (leukemia)

Doctors do not know the exact causes of leukaemia. But there are risk factors that can increase your chance of developing it.

Having one or more risk factors does not mean you will get leukaemia. Also, having no risk factors does not mean you will not develop leukaemia.

We have more information about the risk factors and causes of leukaemia.

Diagnosis of leukaemia (leukemia)

Some people are diagnosed with leukaemia after being taken to hospital with symptoms that have developed quickly. Others go to see their GP about symptoms. If it is possible you have leukaemia, you will see a doctor who specialises in diagnosing and treating blood problems. This doctor is called a haematologist.

Tests to diagnose leukaemia include:

  • Blood tests

    You will have blood tests to check the numbers of the different types of blood cell (called a full blood count) and to look for leukaemia cells.

  • Bone marrow tests

    Samples of your bone marrow are checked for leukaemia cells. We have more information about having a bone marrow test.

We have more information about these and any other tests you may have to diagnose leukaemia.

Treatment for leukaemia (leukemia)

A team of specialists will meet to discuss the best possible treatment for you. This is called a multidisciplinary team (MDT).

Your doctor or specialist nurse will explain the different treatments and their side effects. They will also talk to you about things to consider when making treatment decisions.

If you have an acute leukaemia you will usually need to start treatment as soon as possible. You will have some treatment as an inpatient in hospital. This can mean being in hospital for a few weeks at a time. If you have a chronic leukaemia you can usually have treatment as an outpatient. You may not need to start treatment straight away.

We have more information about:

After leukaemia (leukemia) treatment

What happens after treatment depends on the type of leukaemia and the treatment you had.

You can find out more in our information about:

Getting support

Everyone has their own way of dealing with illness and the different emotions they experience. You may find it helpful to talk things over with family and friends or your doctor or nurse.

Macmillan can offer emotional, practical and financial help and support.

The organisations below also offer information and support:

  • Blood Cancer UK
    Blood Cancer UK is a blood cancer research charity that provides information and support on any type of blood cancer.
  • Leukaemia CARE
    Leukaemia CARE provides care and support to patients, their families and carers whose lives have been affected by leukaemia, lymphoma or a related blood disorder.

About our information


  • Reviewers

    This information has been written, revised and edited by Macmillan Cancer Support’s Cancer Information Development team. It has been reviewed by expert medical and health professionals and people living with cancer. It has been approved by Senior Medical Editors, Dr Anne Parker, Consultant Haematologist; and Dr Helen Marr, Consultant Haematologist.

    Our cancer information has been awarded the PIF TICK. Created by the Patient Information Forum, this quality mark shows we meet PIF’s 10 criteria for trustworthy health information.

How we can help

Clinical Information Nurse Specialists
Our Cancer Information Nurse Specialists are dedicated cancer nurses available to talk to on our Macmillan Cancer Support Line. 
0808 808 00 00
7 days a week, 8am - 8pm
Email us
Get in touch via this form
Chat online
7 days a week, 8am - 8pm
Online Community
An anonymous network of people affected by leukaemia which is free to join. Share experiences, ask questions and talk to people who understand.
Help in your area
What's going on near you? Find out about support groups, where to get information and how to get involved with Macmillan where you live.