The most important allergens in allergic rhinitis.

The distribution of allergens, found on thorough allergy work-up in a series of 770 patients with seasonal and perennial nasal symptoms, is reported. The percentages of positive reactions to grass, tree, and herb pollens were equally high (30--40%) but, clinically, pollens from grasses (Timothy, Alopecurus, Kentucky Blue and Meadow fescue), birch and mugwort (Artemisia) were the most important. In the Nordic countries house dust is evidently the commonest causative agent in perennial rhinitis but the heterogenous composition of house dust makes it difficult to determine potent allergenic factors. Sensitivity to house dust was present in 44% of the patients; a positive reaction to mite extract in only 10%. Animal danders were not found to be great importance in allergic rhinitis (13--18%). Reactions to moulds were observed in 9% of the patients.