Pretty much everyone will suffer from a cough from time to time, and the condition is one of the most common reasons why people visit a pharmacy. A cough is actually a reflex response that clears the airways of unwanted irritants, and it involves several parts of the body.

Cough receptors are located in the walls of the airways and are triggered by irritants such as smoke, microorganisms or a condition such as asthma. The receptors trigger an impulse that runs along the vagus nerves to the cough centre, which is located in the medulla oblongata of the brain. This in turn sends nerve impulses to the respiratory muscles, causing a sudden inhalation of air.

This becomes momentarily trapped in the lungs due to closure of the epiglottis and vocal cords in the throat. The intercostal muscles between the ribs, the abdominal muscles and the diaphragm then contract, forcing the epiglottis and vocal cords to open. The pressure of the air as it leaves the body, hopefully taking with it the original airway irritant, causes the sensation – and characteristic noise – known as a cough.