Allergic rhinitis is the most common manifestation of upper respiratory tract allergy, and may be seasonal or perennial. Seasonal allergic rhinitis often is caused by pollen and insects, whereas perennial allergic rhinitis often is caused by dust and animal dander. Molds can cause either type. Maximal symptoms of seasonal allergic rhinitis depend on geographic location, but they occur between late spring and early fall.

On physical examination, the nasal turbinates are classically described as pale, blue, and edematous with a thin, clear mucous covering. The turbinates may be erythematous and swollen. Patients may have “allergic shiners,” dark discolorations under the eyes that result from venous stasis in the thin tissues of the eyelids caused by nasal congestion. Children may have a horizontal crease across the lower nose caused by repeated rubbing and subsequent scarring in this area. Chronic childhood nasal obstruction eventually leads to mouth breathing and typical “adenoid facies,” with a raised upper lip, mandible maintained open, and small poorly developed nostrils.

Symptoms of allergic rhinitis include nasal congestion, watery rhinorrhea, sneezing, nasal pruritus, conjunctivitis, tearing, itchy palate, and postnasal drip. The differential diagnosis includes vasomotor rhinitis, rhinitis medicamentosa, hormonal rhinitis, the common cold, sinusitis, and structural lesions that lead to nasal obstruction, such as nasal septal deviation, adenoid hyperplasia, nasal foreign body, and tumors of the nose and nasopharynx. Complications and sequelae of allergic rhinitis include serous otitis media, sinusitis, adenotonsillar hyperplasia, lingual tonsillar hyperplasia, sore throat, and paranasal sinus polyps and mucoceles (Table 19-3).

Allergic reactions are responsible for some diseases of the outer, middle, and inner ears. The external ear is susceptible to allergic eczema. This may be caused by a food allergy or an allergic reaction to a fungal infection of the external ear. In both instances, eczema leads to loss of normal skin integrity, which may lead to bacterial invasion and otitis externa. Otitis media caused by allergic eustachian tube obstruction often is a complication of allergic rhinitis. This is believed to result from loss of normal ear aeration and loss of equalization with atmospheric pressure. This effusion, which leads to a conductive hearing loss, may become infected, and purulent otitis media may develop. Allergy will also have a direct effect on middle ear mucosa. Mucosa previously sensitized to an allergen will respond with a full immune response. Mediators present in the middle ear with activate-primed neutrophils and eosinophils to chronically release allergy-related extracellular proteins, which also lead to effusion and inflammation.