Pathophysiology and pharmacotherapy of common upper respiratory diseases.

The response of the upper respiratory tract to many environmental factors can be used both to analyze the body's inflammatory process and to choose appropriate therapy. The nose is the major pathway to the lungs, upper airways, sinuses, middle ears, and other parts of the body, and its reactions often represent a major portion of the problem. The most common upper respiratory illnesses are upper respiratory infections (URIs), primarily viral, followed by secondary bacterial infections. Approximately 20% of the total population may manifest allergic rhinitis, which is mediated by immunoglobulin E. This condition is often referred to as hay fever, although there is no direct allergy to hay, and there is no fever. The differential diagnosis includes nonallergic rhinitis with eosinophils, which mimics the pathophysiology of allergic rhinitis but yields negative results on skin testing; vasomotor and hormonal rhinitis; and rhinitis medicamentosa, the rebound congestion associated with overuse of topical adrenergic agents. Therapeutic options include avoiding causative agents, immunotherapy, and pharmacotherapy. Antihistamines produce excellent results in allergic rhinitis when sneezing and itching are present, but are of minimal value as decongestants. The alpha-adrenergic agonists are the optimum choices for congestion associated with viral URIs, and allergic or nonallergic rhinitis. Of major importance are accurate diagnosis, selection of appropriate therapy, and patient compliance.