A Mexican script is valid in the US as long as it is FDA approved, and you have no more than a month supply. It says so on the DEA's website and I know people that have had no problem crossing the border with OC's with a script. Some border guards can be dicks about this, but it is legal. This has more to do with tourism to the US than anything else,(people coming here, many have meds they need to take, just let them in with out of country scripts). The Mexico way is just a lil old exploiting a rule made for something totally different. If anyone wants me to dig up the link I will, but if you want to, you can find it yourself cause it is in DBs info on whether you can import drugs from Mexico to the US.