Causes

A high white blood cell count usually indicates:

• An increased production of white blood cells to fight an infection
• A reaction to a drug that increases white blood cell production
• A disease of bone marrow, causing abnormally high production of white blood cells
• An immune system disorder that increases white blood cell production

Specific causes of a high white blood cell count include:

• Acute lymphocytic leukemia
• Acute myelogenous leukemia (AML)
• Allergy, especially severe allergic reactions
• Chronic lymphocytic leukemia
• Chronic myelogenous leukemia
• Drugs, such as corticosteroids and epinephrine
• Infections, bacterial or viral
• Myelofibrosis (a bone marrow disorder)
• Polycythemia vera
• Rheumatoid arthritis (inflammatory joint disease)
• Smoking
• Stress, such as severe emotional or physical stress
• Tuberculosis
• Whooping cough