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A cough is persistent if it lasts for more than 3 weeks and chronic if it lasts for more than 8 weeks.

Causes of persistent cough

If the cough persists after a common cold or bronchitis, it’s often the result (sequela) of a viral infection. The most common cause is sinusitis, which tends to prolong the cough. Another possible cause is asthma, which often begins with a persistent cough following an infection.

If the persistent cough has begun without prior flu symptoms, the cause is often some other pulmonary condition, many of which can cause a cough. A fairly common cause of persistent cough is reflux, where the acidic contents of the stomach may travel up to the throat and from there to the bronchi. Coughing can also be an adverse effect of some medicines.

Sometimes an examination fails to reveal the cause of a persistent cough. This state is called cough hypersensitivity syndrome, also referred to as idiopathic chronic cough, where the cough is a reflex associated with the respiratory organs. In cough hypersensitivity syndrome, the cough reflex is thought to be over-sensitized for reasons at present unknown.

  • Upper respiratory tract cough symptom (phlegm in back of throat)
  • Post-infection cough (hyperreactivity of the bronchi)
  • Asthma
  • Reflux
  • Smoking and similar irritants
  • Chronic bronchitis and early stages of chronic obstructive pulmonary disease (smoking)
  • Medications, such as ACE blockers, beta blockers in asthmatics, nitrofurantoin and methotrexate.

Always seek non-urgent care if a cough lasts more than several weeks with no apparent reason.

Seek immediate treatment if these symptoms present themselves

  • heavy amount of bloody sputum
  • shortness or wheezing of breath
  • blue lips
  • general ill health
  • chest pain

Seek treatment within a few days if these symptoms present themselves

  • bloody or yellowish sputum
  • breathing more difficult than normally
  • persistent feverish
  • strong pain of the face or ear

Treatment of persistent cough

  • Home treatment of a cough related to an upper respiratory infection includes rest, honey, sprays affecting nasal membranes, throat lozenges, vapor inhalation, pharmacy-bought water pipes or other moisturising methods. Cortison-based nasal sprays may alleviate the cough, especially when it’s related to upper respiratory infections.
  • Cough suppressants obtained with a doctor’s prescription have been deemed as not very effective.
  • Persistent cough resulting from an illness usually disappears when the illness is cured.

Information sources: The Finnish Medical Society Duodecim: Terveysportti, Lääkärin tietokanta database

FSHS General Practitioner / 30 January 2024

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