Question: Is it legal to order Tylenol 3 from Canada over the Internet?
Answer: No. There has been a great deal of confusion caused by the Internet when it comes to certain types of activities or purchase. Here, since the seller is outside of the United States, they need only to be licensed to sell drugs under the laws of Canada. US laws currently do not give US federal agencies the ability to regulate the sales of drugs over the Internet from foreign sellers.
However, if a doctor's prescription is required to possess the drug in the United States, then you still need to have the prescription to legally use the drug. So, an Internet-based pharmacy may sell you the drug, but they may have a disclaimer on their site saying something like, 'a physician's prescription may be required to use this drug.' It may be cheaper to buy drugs over the Internet (or similarly by going over the border to Mexico), but you still need a prescription to make it legal for you to possess and use the drug in the United States.