Food and Drug Administration (FDA) Commissioner Scott Gottlieb announced new measures to counter the growing opioid epidemic on Tuesday, including enforcement actions against dozens of websites that sell addictive painkillers.

#FDA is unveiling a comprehensive effort to crack down on opioid sales online; includes new and sustained enforcement efforts, steps to work collaboratively with reputable social media sites to cut down on ads for sales, and more interdiction work in international mail facilities,” Gottlieb said in a statement on Twitter.

“We’re also taking new steps to evaluate the flow of opioids and counterfeits coming through international mail; working closely with our outstanding partners. Consumers buying opioids online are often getting pressed fentanyl products advertised as Vicodin, Percocet, or OxyContin,” he added.

Gottlieb announced that his agency sent warning letters to 53 websites marketing unapproved opioids, ordering them to stop the illegal marketing practices concerning “potentially dangerous, unapproved and misbranded” drugs. The medications listed include tramadol and oxycodone.

“The FDA is taking additional steps to protect U.S. consumers from illicit opioids by targeting the websites that illegally market them and other illicit drugs,” he said. “The internet is virtually awash in illegal narcotics and we’re going to be taking new steps to work with legitimate internet firms to voluntarily crack down on these sales.”

“Opioids bought online may be counterfeit and could contain other dangerous substances,” Gottlieb continued. “Consumers who use these products take significant risk with their lives. The new warning letters are part of a comprehensive campaign to target illegal sales of unapproved opioids. We’ll be following these actions with additional steps in coming months to crack down on the flow of illegal, unapproved opioids sold online and shipped through the mail.”

President Donald Trump issued a Presidential Memorandum October 26, 2017 for Agency Heads to combat the opioid crisis on and directed the Department of Health and Human Services to declare the epidemic a Public Health Emergency.

“We are already distributing nearly $1 billion in grants for addiction prevention and treatment, and more than $50 million to support law enforcement programs that assist those facing prison and facing addiction,” the memorandum reads.

“We have also launched an $81 million partnership to research better pain management techniques for our incredible veterans,” Trump added.