Thanks for your question on Healthcare Magic.
I can understand your concern.
Yes, you can give Virtussin AC
cough syrup to your son.
Virtussin AC is having
dextromethorphan, chlorpheniramime.
These are for drug irritant cough.
Possibility of viral infection (contacted by you) is more likely in your son's case.
So give this syrup to him, 5 ml, thrice daily.
Along with this syrup, tell him to drink plenty of water, avoid oily and spicy food and do warm water gargles 5-6 times a day.
Don't worry, he will be alright with all these.
If not Improving after 5 days then
consult doctor.
Hope I have solved your query. I will be happy to help you further. Wishing good health to your son.Thanks.