Cough

Definition:

A sudden, forceful release of air from the lungs.

Considerations:

The cough reflex is one of the body's best defense mechanisms. Irritation or obstruction in the breathing tubes activates this reflex, and the strong rush of air helps clear material from the breathing tubes.

A cough is more helpful if it is producing and expelling something, such as phlegm (sputum). Such a cough is termed "productive" and usually should not be suppressed by drugs.

Minor irritations in the throat can start the cough reflex even though normal mucus is the only material to be expelled. (This is called a "dry" cough.)

Mucus from the nasal passages can drain into the throat and lungs (postnasal drip) and trigger the cough reflex. Such coughs are not helpful and may be treated with cough suppressants.

In infants, coughing is unusual and may indicate a serious lung problem.

In diagnosing the cause of a cough, it is important to notice details about the cough, such as the type of cough, does it bring up mucus or phlegm, and so on.

A cough that is caused by bronchitis or similar infection commonly lasts for up to 2 weeks. However, a cough that persists longer than this should be evaluated by the health care provider.

A cough may occasionally indicate a serious condition:

• when blood is coughed up
• when it is accompanied by chest pain
• when there is difficulty breathing or shortness of breath
• if there is also an unintentional weight loss

Common causes:

• smoking (smoke destroys the cells in the lining of the breathing tubes so that mucus cannot be expelled normally, leading to a chronic cough)
  • including passive or secondhand smoke
• common cold, influenza, and other viral infections (with yellow or white mucus) are the most common causes
• drugs (such as ACE inhibitors or expectorants) cause persistent, dry, nonproductive coughs
• stress (if the cough disappears during sleep, then stress may be the cause)
• allergies
• aspiration (see foreign object aspiration or ingestion)
• atelectasis
• bacterial infection (bronchiectasis, bronchitis, pneumonia, sinusitis, or tracheitis)
  • often with rusty or green mucus

• congestive heart failure
• environmental pollution
• gastroesophageal reflux
• infections (such as Chlamydia, Mycoplasma, pertussis)
• postnasal drip
• asthma
• viral infection (bronchiolitis, croup, pneumonia, upper respiratory infection)
• diagnostic tests (such as bronchoscopy, chest X-ray, or pulmonary function tests)
• medical treatments (such as intermittent positive pressure breathing, or incentive spirometry)
• lung cancer
• emphysema

Note: There are other causes of a cough. This list is not all inclusive, and the causes are not presented in order of likelihood. The causes of this symptom can include unlikely diseases and medications. Furthermore, the causes may vary based on age and gender of the affected person, as well as on the specific characteristics of the symptom such as quality, time course, aggravating factors, relieving factors, and associated complaints.