The Food and Drug Administration has launched an awareness campaign to warn consumers that the vast majority of online pharmacies are offering counterfeit drugs.
According to the FDA, only three percent of online pharmacies reviewed by the National Association of Boards of Pharmacy comply with US pharmacy laws and practice standards.
"Many illegal online pharmacies use fake 'storefronts' to make you think they are real pharmacies," it warns.
"However, the products they provide may be fake, expired and otherwise unsafe. In fact, many online pharmacy scams are so sophisticated that even health care professionals can have a hard time detecting illegal sites at first glance."
To be safe, customers should make sure that the pharmacy requires a valid prescription before dispensing drugs, and has both a physical address and state license within the US.
At best, says the FDA, customers may be getting fake drugs that could be less effective or have unexpected side effects. On top of this, it points out, customers can be putting themselves at financial risk by handing over personal and banking information.
"These sites may infect your computer with viruses, and they may sell your information to other illegal websites and internet scams," it says.
Nevertheless, says the FDA, nearly a quarter of Americans have bought prescription drugs online, largely because of the lower cost. it's hoping to spread the word through doctors, legitimate pharmacists and is even teaming up with Interpol.