[Anaphylactic shock to celery and sensitization to ragweed and mugwort. Crossed or concomitant allergy?].

Two cases of anaphylactoid reaction from hypersensitivity to celery are reported. The two patients were also allergic to ragweed and mugwort pollen. The RAST inhibition test suggested slight cross-allergenicity between celery and mugwort pollen. The common allergenic factor could have been the alpha-methylene gamma-butyrolactone group.