My baby is 9 mo's old, and is with the common cold for more than 4 weeks. is it ok to give him some cough suppressant?

Evaluation needed: Diagnosing and treating cough in infants is especially challenging. The typical "cold" should only last about 7-10 days. If a cough is persisting beyond that time, it is reasonable to have an evaluation, as other considerations such as asthma could be an issue. Cough suppressants are not recommended for infants. The cause of the cough should be addressed first.