Links between chronic cough and allergic diseases

The combined presentation of chronic cough and allergic diseases is frequent in adults, and more so in children. With chronic cough lasting for more than eight weeks, and after a systematic chest X-ray examination, chronic cough occurring in an allergic context may be associated with four types of ailments: eosinophilic airway disorders including allergic asthma, cough variant asthma and, allergic rhinitis, atypical forms of hypersensitivity pneumonitis whose clinical manifestations are predominantly marked by a chronic cough, some cases of drug hypersensitivity, and finally, a chronic cough related to modifications of the cough reflex leading, through various mechanisms, to the decreased threshold of response towards inhaled irritants. Even if well performed, the assessment of a chronic cough in an allergic context is delicate and warrants repeated consultations and the use of additional exploration tests, sometimes invasive. Although it improves the condition of most patients, symptomatic treatment with corticosteroid alone is not sufficient as it may, failing a due diagnosis, lead to a relapse and damaging delay in diagnosis. (C) 2011 Elsevier Masson SAS. All rights reserved.