Cough is a reflex contraction of the muscles which control the movement of the lungs, usually caused by irritation of the air passages. It is one of the most common symptoms presenting to the general practitioner. There are many possible causes, many of which are minor and self limiting; however the possibility of uncommon but serious causes, such as cancer also need to be kept in mind. Coughs are generally classified as being acute (present for less than 3 weeks) or chronic (more than 3 weeks).

Causes of cough

Short term causes:

  • Respiratory infections – viral or bacterial
  • Inhaled irritants – smoking, dust, fumes
  • Inhaled foreign body
  • Whooping cough


Longer term causes:


Serious causes:

Lung cancer accounts for approximately 25% of cancer deaths in the United States, with smoking being the most common cause. Bronchogenic carcinoma accounts for over 95% of primary lung malignancies. Most patients are aged between 50-70 years. The most common symptoms on presentation are cough, chest pain, wheezing, coughing up blood and breathlessness. Weight loss and a hoarse voice may also be noted.

Physical examination:

  • general examination: raised lymph nodes, fever, weight loss.
  • examination of sputum
  • examination of lungs and heart


Tests:

  • chest x-ray
  • blood tests
  • sputum culture
  • lung function tests
  • CT of the lung

Treatment:

The treatment of cough is primarily directed at the underlying cause, such as treating infections with antibiotics or treating reflux disease that may be causing cough. A careful assessment of the cough should be made, noting any associated systemic symptoms such as weight loss. Medications which may be causing cough should be stopped for a time to see if this results in improvement of symptoms; and an attempt should be made to limit occupational/social exposures (fumes, cigarette smoke). In the case of lung cancer, treatment will depend on the type of carcinoma. Referral to a respiratory physician is recommended. Certain types of lung cancer may be treated with surgery if diagnosed early enough, or chemotherapy. Radiotherapy is usually given to reduce tumour masses which may be causing an irritative cough.

Medications:

Morphine derived medications may improve cough when there are no underlying treatable causes. They work by acting on the morphine receptors found within the lung to decrease the reactivity of the nerves which convey irritative sensations from within the lung to the brain. Steroid medications such as dexamethasone and prednisolone are potent anti- inflammatory drugs which may be used to suppress lung inflammation or irritation causing cough. They may also decrease the amount of inflammation and swelling around a tumour.

More information

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References