Allergic rhinitis, histamine, and otitis media.

Otitis media (OM) is a common and costly medical condition, especially in children. Most episodes of OM are associated with an upper respiratory viral infection and are short-lived and self-limiting with or without medical treatment. However, chronic OM with effusion (OME) has significant sequelae, is refractory to most medical treatments, and frequently requires surgical intervention. The pathophysiology of OME is complex and involves both eustachian tube (ET) dysfunction and middle ear pressure dysregulation. OM likely results from an increase in blood flow to and, thus, gas loss from the middle ear, in combination with a dysfunctional ET that can not resupply that gas. These processes could be induced by viral and/or allergen-driven inflammation. A large body of epidemiologic and mechanistic evidence supports a role for allergic rhinitis as a risk for OM. Indeed, evidence also supports a role for histamine in both conditions. However, not all such evidence is supportive of this relationship and a causal relationship between the two conditions has not been definitively proven. Moreover, therapeutic trials using common allergy therapies have either not been conducted or showed no benefit in OM. This prompted the 2004 clinical practice guidelines on OM to conclude that no recommendations could be made for "... allergy management as a treatment for OME based on insufficient evidence of therapeutic efficacy or a causal relationship between allergy and OME." Nonetheless, given the strong likelihood of allergy as a risk factor for OM, allergic rhinitis patients should be evaluated for OM and patients with OME should be considered for an allergy evaluation. If significant allergic rhinitis is diagnosed in a patient with OME, it should be treated aggressively (as in any case of moderate to severe allergic rhinitis) until further studies are conducted. No definitive conclusions about a role for food allergy in causing or treating OM can be made. Clearly, more studies are needed to examine the relationship between these two important conditions.