Cough: differential diagnosis and treatment.

Cough is a complex physiologic event that protects the lungs from mechanical, chemical, and thermal injury. It is a normal reflex and therefore helps humans to adapt to an ever-changing environment. Cough can also be a pathologic reflex in that it may be an important and often the only sign of serious disease, may significantly contribute to the spread of airborne infection, and in some instances, may result in severe functional or structural damage to the organism. This article focuses on the pathophysiology of the afferent limb of the cough reflex, including a discussion of the causes, the diagnostic workup, and the treatment of cough.