Yes, it can be legal as long as certain rules are followed. They are found only online; not all of them are registered pharmacies and sell drugs legally, so buying from them is potentially unsafe. Not all sites are the same. Purchasing from them, through your insurer, is as safe as using your local pharmacy. If neither of those approaches works, then follow the steps below for finding a safe and legal pharmacy to order from. Make yourself familiar with the requirements that must be met to make a legal purchase of drugs through the Internet.According to price-comparison site , generic Revatio will cost you as little as $ per pill, depending on where you fill your prescription. That’s compared with . There are ways you can identify a safe online pharmacy. These pharmacies: Always require a doctor’s prescription. Provide a physical address and telephone number in the U.S. . For example, a year-old Illinois man with episodes of chest pain and a family history of heart disease died of a heart attack last March after buying the impotence drug Viagra .