The most common illnesses in humans are the respiratory tract infections caused by viruses. When limited to the upper respiratory region, these infections often are designated as "a common cold." Viruses commonly associated with these upper respiratory infections (URI) include rhinoviruses (RVs), respiratory syncytial virus, influenza virus, parainfluenza virus, corona virus, and adenoviruses. Clinical observations have suggested that patients with allergic rhinitis and asthma experience more pronounced symptoms during a viral URI than patients who do not have allergies and who are infected with the same virus under similar circumstances. Using an experimental virus infection model in human volunteers with and without allergic rhinitis, several groups of clinical investigators have studied the effects of experimental RV infections. These observations indicate that the experimental virus infection may induce host responses that provoke enhanced immunoglobulin E (IgE) synthesis. Whether this translates into enhanced symptoms has been suggested in one study but not in another. This article will review these studies, which suggest that it is the host response to the virus and not the virus itself that plays the major role in symptom pathogenesis.