Do Allergy Shots Help Asthma?

Because allergens trigger bronchoconstriction in more than half of asthmatics, investigators at Johns Hopkins School of Medicine studied ragweed pollen immunotherapy in asthmatics with symptoms during ragweed pollination season. Compared with placebo, purified ragweed pollen immunotherapy produced a small but statistically significant increase in peak expiratory flow and reduced the use of asthma medications during the first year. However, benefits were not apparent during the second year of therapy. Because asthmatics usually respond to multiple allergens (including house dust mite feces, which are generally not responsive to allergy shots), immunotherapy for asthma appears to be of limited value.