Beyond that amount, you will need a prescription from a licensed U. When hypertension occurs in the lungs, the heart must work harder to pump enough blood through the lungs. These medicines prevent an enzyme called phosphodiesterase type-5 from working too quickly. The FDA also has a guide for the importation of drugs originally intended for foreign markets. The price difference is so great that some Americans travel to Mexico to take advantage of the savings.If you’re interested in buying Viagra online, five of the best options available are Hims, Roman, Lemonaid, Optum Store, and REX MD. Read on for full details on the process and pricing. A quick. Safeway $ retail Save 94% $ Get free savings Low price Walgreens $ retail Save 94% $ Get free savings directions Closest store Rite Aid. By Marian Anne Eure Updated on July 17, Medically reviewed by Mary Choy, PharmD Fact checked by Heather Mercer Table of Contents Prescriptions From Mexico When Is It Legal to Import Drugs? Safety Risks Required Documentation Mexican pharmacies offer prescription medications at lower prices than pharmacies in the United .