Cromolyn (sodium cromoglycate), sprayed into the nose, reduces symptoms of seasonal allergies by interrupting the release of symptoms triggers such as histamines and leukotrienes.
Most Effective If Start Using Before Symptoms Develop
Cromolyn sprays are most effective when started early in the season, before symptoms develop. If allergic symptoms are present already, cromolyn is not as effective as steroid sprays. Cromolyn sprays also must be used three to four times a day, since the protective effect lasts only about four to eight hours.
In general, side effects of cromolyn are minor and do not last long. In studies, the side effects most often mentioned are sneezing, stinging or burning sensation in the nose, and, very rarely, nosebleed.