How long can a post-infectious cough last, and when should it be assessed?
In adults, post-infectious cough usually describes a cough lasting three to eight weeks after a respiratory infection, after other causes are excluded. It often improves gradually, but breathlessness, blood or deterioration needs assessment without waiting for that period to end.
Details
Duration alone is not diagnostic
A clinician may consider asthma, reflux, certain blood-pressure medicines or infections such as pertussis. Repeated coughing fits followed by vomiting or a whoop deserve discussion, especially with exposure to infants or immunocompromised people.
Are inhalers or cough medicines needed?
Trials have not established a clear benefit from routine medicines for every post-infectious cough. Do not start antibiotics, steroids or inhalers solely because the symptom persists. Treatment differs if assessment identifies asthma or another specific cause.
Arrange follow-up
If the cough does not improve or lasts beyond eight weeks, arrange further assessment. Seek help earlier for blood, breathlessness, weight loss or concerning new symptoms. This adult duration category should never be used to postpone assessment of an unwell child.
Related reading: When does a cough need antibiotics, and when will they not help?.