The U.S. Food and Drug Administration is finally taking action against online “pharmacies” selling illegal opioid medications to the public. A total of 53 websites, including AnonShop and OneStopPharma, are currently operated by nine companies which have received warning letters from the FDA ordering them to cease operation – or face more serious consequences.

The FDA is also enlisting social media sites and mail services to assist with controlling the flow of illicit opioids, which include unapproved formulations such as tramadol as well as counterfeit and misbranded prescriptions. The latter is of particular concern. According to FDA commissioner Dr. Scott Gottlieb, consumers who purchase opioids on the Web believe they are purchasing Vicodin or oxycodone but are often getting fentanyl instead.

These products may also be adulterated or expired. In a press statement, Gottlieb said, “The internet is virtually awash in illegal narcotics…we’re going to be taking new steps to work with legitimate internet firms to voluntarily crack down on these sales.” Earlier this year, Senator Rob Portman (R-OH), who heads the Senate Subcommittee on Investigations, noted that the purchase of illegal opioid medications through Internet websites is “as easy as buying any other product online.”

In April, Gottlieb pointed out that the number of advertisements for opioid sales without a prescription has increased dramatically in recent years. At that time, he said, “The easy availability and online purchase of these products from illegal drug peddlers is rampant and fuels the opioid crisis…Internet firms simply aren’t taking practical steps to find and remove these illegal opioid listings.”

Significantly, a number of the opioid websites operated by the nine companies being targeted appeared to have gone offline shortly after the FDA made its announcement on Tuesday. A few of them, such as “OnlinePainPharma.com,” are still up and running. It is not completely clear how much power the FDA has in this matter, but those companies receiving warning letters have been given ten days to comply or face seizure of their products and possible lawsuits – or even criminal charges.

All of this comes at a time that opioid addiction in the U.S. has reached crisis proportions. The Centers for Disease Control reports that over 42,000 overdose deaths in 2016 (the most recent year for which data is available) were attributable to prescription opioid medications. At the same time, legislative attempts on Capitol Hill to address the problem are meeting stiff resistance from industry and insurance company lobbyists, representing corporate and moneyed interests anxious to preserve their profits.

Gottlieb has called for leaders from several Internet companies – including Facebook, Google, Instagram and Twitter – to attend an “opioids summit” on June 27 in order to come up with effective strategies on controlling the illegal online opioid trade.