Published Online: September 23, 2015
A reduction in the sense of smell is a key symptom in allergic rhinitis (AR). It is likely due to a mechanical component as a result of a blockage of the nasal airways through mucosal swelling, as well as an inflammatory component as a result of the responses of the immune system. An intact sense of smell is a key contributor to quality of life as its loss is accompanied by the decreased enjoyment of food and drink, a decrease in social competence, and an increased risk to other factors including food poisoning. With regard to the large numbers of people suffer from AR, and as a consequence could exhibit smell dysfunction, the interaction between AR and the sense of smell warrants further investigation.
To analyze the current knowledge on the interaction of AR and smell, Stuck and Hummel performed a structured review and focused on two aspects: (1) what does AR do to the sense of smell and (2) how effective is the treatment of AR in improving AR-related smell impairment? As a basis of this review, a comprehensive literature search was performed and all human studies, published in English or German and available in current medical databases, were analyzed. The results of this systematic review are now published in The Journal of Allergy and Clinical Immunology (JACI).
Regardless of the importance of this key symptom, surprisingly few studies have investigated the interaction of AR and smell reduction. In particular, controlled studies with standardized smell tests are often missing. The currently available data, however, suggests that smell impairment in AR occurs with a frequency of approximately 10 to 88% with most studies reporting frequencies of smell dysfunction in the range of 20-40%. The frequency and severity of smell reduction increases with the duration and the intensity of the disorder. Accordingly, smell dysfunction is more pronounced in perennial/persistent AR than seasonal AR. Anti-allergic therapy appears to be effective in AR, at least with regard to topical nasal steroids, immunotherapy and antihistamines. Nevertheless, many questions remain unanswered and controlled clinical trials with validated smell tests are necessary to enable the counseling of patients with smell dysfunction due to AR.
The Journal of Allergy and Clinical immunology (JACI) is an official scientific journal of the AAAAI, and is the most-cited journal in the field of allergy and clinical immunology