Aaron S. But there are limits. The medication should be in its original container with a doctor’s instructions printed on the bottle, in English, and generally containing no more than a three month supply. This is especially true with drugs that are available only by prescription in the United States but sold over the counter in Mexico. Sildenafil is in a class of medications called phosphodiesterase PDE inhibitors.It is the active ingredient in viagra and is sold by compound pharmacies in the U.S. such as Riggs Drugs. In Mexico, and other tourist destinations south of the border, you are . It was $ Faced with high U.S. prices for prescription drugs, some Americans cross the border to buy insulin pens and other meds. At least 1 insurer reimburses flights to the . Buying Viagra Abroad 10 years ago Save I wonder if there is an answer out there for me. Can you buy Viagra in parmacies abroad or will I need a perscription. I have tried to .