Seasonal Exacerbation of Asthma Is Frequently Associated with Recurrent Episodes of Acute Urticaria.

BACKGROUND Asthma and urticaria are both partially mediated by an increased release of histamine from highly activated mast cells. They are pathophysiologically different, as mast cell degranulation in these 2 disorders results from different mechanisms. OBJECTIVE To assess the incidence of urticaria in patients with asthma, and of asthma in patients with chronic spontaneous urticaria (CSU). PATIENTS AND METHODS Over 1 year of follow-up, asthma patients (n = 110) were assessed for the incidence and characteristics of urticaria, and a link, if it existed, to seasonal exacerbations and the severity of asthma was traced. We also prospectively assessed CSU patients (n = 95) during the same period of time for the incidence of asthma. Healthy individuals (n = 100), serving as a control group, were also assessed. RESULTS Episodes of urticaria occurred in 26/110 asthma patients (23.6%), but in only 2/100 healthy control subjects (2%) (p < 0.0001). During the 1-year observation period, episodes of urticaria were significantly more frequent in asthma patients with positive skin-prick test reactions (mainly seasonal pollens), and consequently occurred mostly during seasonal asthma exacerbation, i.e. during acute episodes of urticaria. The incidence of asthma in CSU patients was recorded in 10.5% of the group, similar to that in the healthy control population. DISCUSSION Our study demonstrates, for the first time, that asthma patients frequently develop acute urticaria, mainly during seasonal exacerbations. In contrast, CSU patients do not show an increased incidence of asthma.