Eosinophils (%)
Eosinophils (%) is the proportion of your white blood cells that are eosinophils, immune cells involved in allergic reactions and defense against parasites. It's a component of the white blood cell differential.
Eosinophils rise when your immune system responds to allergens or parasites and play a role in asthma and other allergic conditions. Their share of white cells can therefore hint at allergic or parasitic activity.
An above-range eosinophil percentage (eosinophilia) commonly reflects allergies, asthma, eczema, or reactions to certain medications, and in some regions parasitic infections. Because it's a proportion, it's best read with the absolute eosinophil count.
A below-range percentage is generally not a cause for concern and can simply reflect normal variation or the effects of stress or steroids.
Eosinophils typically make up roughly 1-4% of white cells in adults, though this shifts with the rest of the differential. Interpret alongside the absolute count and your clinician's guidance.
Sources
Educational context only, not medical advice or a diagnosis. Reference ranges vary by lab, age and sex; always discuss your results with a clinician.