No, I am not talking about over the counter sales (legal or not). I am talking about prescription sales. Around here, you get your prescription from the doctor, and take it to the pharmacy. The pharmacist reads it, releases the purchase of the medication, and depending on the type of prescription, keeps a copy of it or stamps it as sold. The medication is sold in its original packaging with manufacturer information. This is not the informal system - it is the normal legal system. In fact, I find it very strange and uncomfortable to get pills outside their original packaging in the US.

The TSA is notorious for not recognizing the needs and differences in foreign guests. I would not like to push them in the direction of requiring something foreigners have no means of providing.