Exercise-induced anaphylactic reaction to hazelnut.

Reproducible, exercise-induced anaphylactic reactions occur in some patients only after certain foods have been eaten before exercise. We describe a patient in whom hazelnuts were a triggering factor for exercise-induced anaphylaxis. Skin tests and RAST were positive for nuts and grass and weed pollen. The exercise challenge test after hazelnut ingestion was positive. Food hypersensitivity should be investigated in all cases of exercise-induced anaphylaxis.