Hi thanks for your question.
Cheston contains cetrizine
,paracetomol and phenylpropanolamine
.This combination will dry up screations and will not clear the phelgom. you need a cough syrup which contains mucolytic
for reduction of phelgm such as bromohexine and ambroxol
.Any cough which remains persistent for more than 3 weeks needs investigation.I would suggests you to consult to a physion specialist to will be able to evaluate you for persistent cough
Hope this answers your question.