Asthma exacerbations are linked to variations in air allergens, respiratory infections, and weather.  A study evaluated 2,637 young adult asthma patients. Skin prick test was used to identify sensitizations and asthma attacks were assessed by questionnaire. Patients report more frequent asthma attacks during certain times of the year, ranging from 47% in Sweden to 87% in Spain. These variations were unrelated to sensitization to house dust mite or cat.

Southern European patients with grass sensitization were more likely to report asthma attacks in spring or summer versus winter: odds ratio (OR) 2.60 in March/April versus 4.43 in May/June. In contrast, for Northern European patients, the peaks were smaller and appeared later in the year: OR 1.25 in May/June and 1.66 in July/August. Asthma patients with self-reported hay fever but without grass sensitization did not have seasonal variations.

Author Saraleen Benouni, MD Dr. Benouni specializes in the treatment of asthma, allergies, atopic dermatitis, and immune disorders for both adults and children. She has presented and published research at national allergy meetings and has authored papers on drug allergies and skin conditions. She is a member of the American College and American Academy of Allergy, Asthma, and Immunology, and the Los Angeles Society of Allergy, Asthma, and Clinical Immunology.