They probably think you'll make drugs from it or something.
But that is fucking stupid. Why can't you buy it at the supermarket? You cannot honestly be saying that you have to go to the chemist for cough medicine?
If so, I must live in the lucky country. Oh wait...
You can buy it at a supermarket (or Wal-Mart), or at a pharmacy. I bought it at a pharmacy simply because it was convenient.
Thank goodness! Much easier when your kids are sick, not having to drive to the chemist.
The cold medicine he is buying you don't want to give to your children.