High white blood cell count
Medically reviewed by Drugs.com. Last updated on Dec 15, 2022.
A high white blood cell count is an increase in cells in the blood that fight infections.
What's considered high in a white blood cell count varies from one lab to another. This is because laboratories set their own reference ranges based on the populations they serve. In general, for adults a count of more than 11,000 white blood cells in a microliter of blood is considered high.
A high white blood cell count usually means one of the following has increased the making of white blood cells:
- An infection.
- Reaction to a medicine.
- A bone marrow disease
- An immune system issue.
- Sudden stress such as hard exercise.
Specific causes of a high white blood cell count include:
- Allergy, especially severe allergic reactions
- Bacterial, viral, fungal or parasitic infections
- Churg-Strauss syndrome
- Medicines, such as corticosteroids and epinephrine
- Hay fever (allergic rhinitis)
- Myelofibrosis (a bone marrow disorder)
- Polycythemia vera
- Rheumatoid arthritis
- Whooping cough
When to see a doctor
A test a health care provider orders to diagnose a condition can reveal a high white blood cell count. A high white blood cell count is rarely found by chance.
Talk to your care provider about what your results mean. A high white blood cell count plus results from other tests might show the cause of your illness. Or you might need other tests for more information about your condition.