Definition: cough as the only or main symptom for >3 weeks in children and >8 weeks in adults. Nature of cough: protective reflex. Common causes: chronic rhinitis and bronchitis; post-episodic cough; cough-variant asthma (CVA) and gastroesophageal reflux. Allergic cough (atopic cough), eosinophilic bronchitis, and other so-called recurrent respiratory infections in some children are actually one or more coexisting with chronic cough. However, a radiograph should be taken first to exclude infectious diseases of the lungs. Each of these diseases has its own clinical features, antibiotic treatment is ineffective, and because they affect mucosal immunity, children are at increased risk for allergic diseases, such as eczema, asthma, and antibiotic-associated diarrhea.