What can I give my four month old for a cough and runny nose??

Nothing, I would take a baby that young to the doctor for dosage or call the office and talk to the nurse hotline

Zarbee's cough is safe for two months and up. But usually with a cold like that you just do saline drops, booger snatcher, humidifier and have them somewhat propped when sleeping.

I would make an appointment with the ped just to be on the safe side.