Cough is defined as explosive expiration providing a protective mechanism for clearing the tracheobronchial tree of secretions and foreign material, and is necessary to aid normal oxygenation. Interruption of the cough reflex—as in certain neuromuscular disorders or excessive coughing, which can cause cerebral ischaemia and thus interfere with respiration—can impair this process.

Cough is one of the most common reasons people seek medical attention. It can indicate a minor airway irritation or a serious underlying disorder. Coughs are generally diagnosed into one of two categories:

• Acute cough (less than three weeks duration)—usually from viral/bacterial upper respiratory tract infections (URIs)
• Chronic cough (more than three weeks duration)—attributable to underlying factors. One-fourth of patients have multiple contributing disorders, making systematic evaluation essential.

Aetiology / Risk Factors

• Viral or bacterial URI
• Lower respiratory tract infection, including bronchitis, pneumonia
• Inhaled irritants, such as cigarette smoke, airborne pollutants, or noxious fumes
• Allergies
• Asthma
• Gastro-oesophageal reflux disease (GORD)
• Upper-airway secretions, sinusitis
• Angiotensin-converting enzyme (ACE) inhibitors and beta-blockers
• Aspiration (bulimia, alcoholism, stroke)
• Congestive heart failure
• Stimulation of neural receptors in the pleura, pericardium, or ears (severe wax impaction) may cause chronic coughs.
• Chronic cough—appears in 14% to 23% of adult non-smokers and in 25% to 50% of adult smokers, increasing proportionately with the number of cigarettes smoked per day
• Immunosuppressive diseases
• IV drug user

Symptoms & Signs

• Upper Respiratory Infection
• Postnasal drip
• Wheezing (cough variant asthma)
• Heartburn (GORD)
• Regurgitation (bulimia)
• Fever/chills/night sweats (pulmonary tuberculosis)
• Oedema (congestive heart failure)
• Weight loss (cancer)
• Features of the cough: dry, hacking, or moist and productive; paroxysmal, etc.
• Sputum
• Dyspnoea