The most common signs of leukaemia are persistent tiredness, pale skin, frequent or slow-to-clear infections, fevers, easy bruising or bleeding, tiny red spots on the skin (petechiae), bone or joint pain, swollen lymph glands and unexplained weight loss or night sweats. These signs arise because leukaemia cells crowd out normal blood production in the bone marrow. None of them is specific, but a combination, or symptoms that persist, should prompt a simple blood test.
In my practice, I see two groups: patients worried by a symptom they have read about, and colleagues seeking advice about an abnormal blood count. This guide is written for both.
What Is Leukaemia?
Leukaemia is a cancer of the blood-forming cells in the bone marrow. It leads to the uncontrolled production of abnormal white blood cells, which do not work properly and suppress the production of normal blood cells. It is one of several haematological disorders that affect the blood and marrow.
The four main types are acute myeloid leukaemia (AML), acute lymphoblastic leukaemia (ALL), chronic myeloid leukaemia (CML) and chronic lymphocytic leukaemia (CLL). ALL is the most common cancer in children, while AML and CLL occur mainly in older adults.
Who Is at Higher Risk?
Most people who develop leukaemia have no identifiable risk factor. Recognised factors include increasing age, previous chemotherapy or radiotherapy, high-dose radiation exposure, long-term benzene exposure, smoking (for AML), and certain genetic conditions such as Down syndrome. Knowing these factors can raise a clinician’s level of suspicion, but their absence should never delay a blood test when signs are present.
Why Leukaemia Causes Its Signs
Most signs of leukaemia can be traced to one of three mechanisms. Understanding them helps patients make sense of their symptoms and helps clinicians interpret them.
| Mechanism | Resulting signs |
|---|---|
| Too few red blood cells (anaemia) | Tiredness, pallor, breathlessness, palpitations, dizziness |
| Too few working white cells (neutropenia) | Recurrent infections, fevers, mouth ulcers, infections slow to heal |
| Too few platelets (thrombocytopenia) | Easy bruising, petechiae, nosebleeds, bleeding gums, heavy periods |
| Leukaemia cells building up in tissues | Bone pain, swollen lymph nodes, enlarged spleen or liver, gum swelling, skin lumps |
| Effects of the cancer on the body | Night sweats, fever without infection, weight loss, loss of appetite |
Signs to Watch For
Common Signs
- Fatigue and weakness that does not improve with rest
- Pale skin and breathlessness on exertion
- Frequent infections, such as chest infections, mouth ulcers or skin infections
- Unexplained bruising or bleeding, including prolonged nosebleeds and bleeding gums
- Petechiae: pinpoint red or purple spots that do not fade when pressed
- Bone or joint pain, particularly in the long bones, back or sternum
- Swollen lymph nodes in the neck, armpits or groin
- Night sweats, fevers and weight loss
Less Common Signs
- A sense of fullness or discomfort under the left ribs from an enlarged spleen
- Swollen, bleeding gums, seen in some types of AML
- Headaches, vomiting or visual changes if leukaemia affects the nervous system
- Breathlessness or facial swelling from an enlarged mass in the chest, occasionally seen in T-cell ALL
Acute Versus Chronic Presentations
Acute leukaemias tend to cause symptoms that develop over days to weeks, and people can become unwell quickly. Chronic leukaemias progress slowly; many people with CLL or CML have no symptoms and are diagnosed after a routine blood test shows a raised white cell count.
Signs in Children
Children with leukaemia often present with tiredness, pallor, bruising, fevers and a limp or refusal to walk due to bone pain. Because these symptoms overlap with common childhood illnesses, persistence and combination are the key clues.
Guidance for Medical Professionals
A full blood count and blood film is the key first investigation. Red flags that warrant urgent discussion with haematology include:
- Blast cells on the blood film
- Unexplained low counts in two or more cell lines (pancytopenia or bicytopenia)
- A very high white cell count, especially with symptoms
- Unexplained petechiae or bruising in a child, or with an enlarged spleen or lymph nodes
- A persistent lymphocytosis with lymphadenopathy in an older adult
Very high white cell counts can cause leukostasis, with breathlessness, confusion or visual disturbance, and a patient with suspected acute leukaemia and fever needs same-day assessment. Diagnosis is confirmed with bone marrow examination, flow cytometry, cytogenetics and molecular testing. Our article on leukaemia symptoms covers symptom patterns in more depth.
What Happens After Diagnosis
Once leukaemia is confirmed, the type and genetic features guide treatment. Options include chemotherapy, targeted drugs, immunotherapy and stem cell transplantation, while some slow-growing chronic leukaemias are monitored before treatment. You can read more in our guide to leukaemia treatment. Families and carers may find our overview of blood disorders for patients and caregivers helpful.
When to See a Doctor
See a doctor if you have tiredness, infections, bruising, night sweats or swollen glands that last more than two to three weeks, or several of these together. A blood test is simple and quick. Seek urgent care the same day for petechiae with a fever, bleeding that will not stop, severe breathlessness, confusion, or a high fever in someone already known to have low blood counts.
Frequently Asked Questions
What is usually the first sign of leukaemia?
Tiredness and pallor from anaemia are often the earliest signs, followed by infections or bruising. In chronic leukaemia, the first sign is frequently an abnormal routine blood test with no symptoms at all.
Can a normal blood test rule out leukaemia?
A completely normal full blood count and film makes leukaemia unlikely, though rare early cases can be missed. If symptoms persist, a repeat test is reasonable.
Are leukaemia bruises different from normal bruises?
They are often unexplained, appear in unusual places such as the back or trunk, and may come with petechiae or bleeding gums. Any unexplained bruising pattern deserves a blood test.
How quickly do leukaemia signs develop?
In acute leukaemia, symptoms usually appear and worsen over a few weeks. In chronic leukaemia, they may develop over months or years, or never appear before diagnosis.
Does leukaemia cause back or bone pain?
It can. Leukaemia cells expanding inside the marrow can cause aching bones or joints, particularly in children with ALL. Most back pain has other causes, but pain with other warning signs should be checked.
