Baby of 4 months has snotty nose and now started to cough. what to do?

Doctor can examine: In the US, the recommendation is NOT to use cold medications such as decongestants, antihistamines, and cough suppressants in babies or young children who have typical cold symptoms. We may use asthma medications when there are asthma symptoms, which can include wheezing, coughing, etc... Each child and each illness has its individual characteristics, so one's doctor should examine.

Depends: The first months are troubled by narrow nasal passages & exposure to dust, fragrances, smoke & other irritants.Baby tries to flush these out of the nose with mucous but this often ends as congestion & produces rattling& cough with breathing. The best rx is washing out the nose with saline & suctioning the remainder. Eliminate irritants from babies environment & this will happen less.