An article published in Der Pneumologe stated that the most frequent cause of acute cough (lasting up to 3 weeks) or subacute cough (3-8 weeks) is a viral infection, which is mostly a self-limiting disease in otherwise healthy persons. The authors reported that some herbal compounds, the antitussive dextromethorphan and ambroxol are effective for symptom relief. However, antibiotics are ineffective and should not be used due to the risk for development of resistance. 

If after appropriate diagnostic procedures the cause of chronic cough—lasting more than eight weeks—cannot be attributed to a well-established respiratory disease, it meets the definition of a disease in its own right, chronic idiopathic (unexplained) cough (CIH). This is triggered by hypersensitivity of the cough reflex. 

The article summarized that even weak low threshold stimuli, e.g. changing temperature, extensive speaking and odors can trigger cough reflex. In the instance of nonresponse to guideline-conform treatment, the definition of chronic refractory cough is met.

Source: Der Pneumologe. 2020 Oct 9;1-9. doi: 10.1007/s10405-020-00346-1.