Pathophysiology and treatment of seasonal allergic rhinitis

Therapeutic approaches to seasonal allergic rhinitis are reviewed in this paper. Pharmacotherapeutic approaches include nonsedative antihistamines, anti-allergic drugs, vasoconstrictors, anticholinergic agents and topical corticosteroids. The choice of treatment depends upon its relative efficacy and safety. Although effective, immunotherapy has been seriously questioned in recent years owing to the occurrence of possibly serious side-effects. Antihistamines are safe and effective for treatment of histamine-mediated symptoms of itching, sneezing and rhinorrhoea. The newer compounds do not cause sedation. For nasal symptoms, topical anti-allergic drugs are not as effective as other treatments. Topical vasoconstrictors are often used, though they cause side-effects when the treatment is prolonged. Anticholinergic drugs are safe and effective for rhinorrhea. Corticosteroids are highly effective for most symptoms, but their administration by oral or parenteral routes cannot be recommended because of side-effects. Topical corticosteroids inactivated by hepatic first pass metabolism are favoured as they are highly effective and safe. Their mechanism of action is not completely understood, but they act through both an anti-inflammatory effect and an anti-allergic activity decreasing mediator release. These drugs are the most effective in the treatment of nasal obstruction because of their anti-inflammatory effect. They are usually administered in response to symptoms, but in the future, it is likely that they will be used prophylactically before the pollen season in order to decrease the priming effect.