Combined effect of cigarette smoking and allergic rhinitis on airway responsiveness to inhaled methacholine.

A group of healthy nonatopic subjects was compared with a group of atopic subjects with allergic rhinitis who were otherwise healthy. They were matched for sex, age, and smoking habits; 15 pairs were nonsmokers and 11 pairs were smokers. Threshold of airway response to inhaled methacholine based on partial flow-volume curves was not significantly different between nonatopic nonsmokers and nonsmokers with allergic rhinitis. However, smokers with allergic rhinitis had a threshold on the average of 3 doubling doses lower than smokers without allergic rhinitis. We concluded that there is a combined effect of chronic cigarette smoking and allergic rhinitis affecting nonspecific airway responsiveness.