There is nothing like good or bad medication , There will be appropriate medication. Banana don't cause cough that is superstitious belief ,if that is fact banana production should be stopped and not to be sold . cough with some food is very rare , because if person has food allergy it's systemic reaction ,cough following some food denotes wheeze following bronchial constriction. So come out of superstitious beliefs ,like banana cause cold , lime cause cold . K  start thinking .