Obtaining prescription drugs in the United States can be back-breakingly expensive if you don't have good insurance (or none at all). The lure of cheap online drugs, therefore, can be strong, and it's perfectly legal in the U.S. to buy your prescriptions from Canada or other countries. But the Internet prescription drug market, not surprisingly, is enormous and pretty seedy. In 2013, the U.S. Food and Drug Administration (FDA) pulled off a sting operation that targeted 9,600 online pharmacies and seized $41 million in illegal and counterfeit drugs [source: Edney].
There are legitimate online pharmacies, but so many of the illegal ones disguise themselves — through website design and URLs that are very close to those of well-known companies — that it can be very difficult to discern what's what. The red-flag rules we mentioned earlier obviously apply here, and you should also make sure that the site requires a signed prescription from your doctor. It's a bad sign if it doesn't. (Of course, it's great if you're trying to buy drugs without a prescription ... but not so great if you'd like to stay on the right side of the law.)
Bottom line, if you buy from a questionable online pharmacy, there's no way of knowing what you're getting, and those pills that show up in the mail could have an incorrect and potentially harmful chemical makeup. There's a reason the drugs are so cheap.