When your infant has a cough you can give them some infant paracetamol and also breastfeed or bottle feed the infant more often to help keep them hydrated as the infant will need more fluids when they have a cough or are sick.
Put a vaporizer or a humidifier to put out steam in your infants room which can help the infant breath better and fight off a cough.
There's not too much you can do or give an infant when they have a cough but do also make sure they get plenty of rest to help fight off the cough.