Most of such episodes of cough and cold are caused due to viral infections which are also associated with some amount of allergic reaction. Levocet M contains levocetirizine along with monteleukast, both of which are right to be given in such a situation. Do not worry, the combination would not be excess for your son. But to be able to comment whether the dose/amount provided is appropriate for your child, I would need to know the body weight of your child, as the dose is calculated according to the body weight. I would suggest you to continue the medication along with steam inhalation which would provide relief. Your doctor must have made the calculations before prescribing the medicine.