What Are Eosinophils in a Blood Test?

Eosinophils are white blood cells that fight parasites and participate in allergic responses. They comprise 1–4% of WBCs.

Normal Range

• 1–4% of WBC
• Absolute: 50–500/µL

High Eosinophils (Eosinophilia)

• Allergic conditions: asthma, hay fever, eczema
• Parasitic infection
• Drug reactions
• Autoimmune disease
• Eosinophilic esophagitis
• Hypereosinophilic syndrome (rare, serious)

Severity

• Mild: 500–1,500/µL
• Moderate: 1,500–5,000/µL
• Severe: above 5,000/µL (organ damage risk)