Buying prescription drugs in Cancun Mexico

Next week I am flying to Cancun for business, and several of my friends and family have asked if I could pick up some medications for them. Apparently it is cheaper in Mexico.
I don’t mind doing this, but I want to make sure that everything is legal. What do I need to know to make sure that I do not encounter any problems? Any medications more of a problem than others? Prescriptions needed or what?

Thanks for any and all info.

I still haven’t decided whether these kinds of threads can live in GQ.

But there’s certainly no need for more than one of them.

I’m going to lump our good neighbors to the north and south together. So I’ll close this thead and ask people to inquire as a tangent to the thread about scrips in Canada.