The US Food and Drug Administration (FDA) has sent warning letters to nine online networks over illegal marketing of opioid medications, such as tramadol and oxycodone.

The networks are AnonShop, Eassybuyonline, Instabill ECS-Rx, One Stop Pharma,, RemedyMart, RxCash.Biz, TramadolHub and XLPharmacy.

These marketers are operating a total of 53 websites that sell potentially dangerous, unapproved and misbranded variants of the medicines that can lead to health problems.

The regulatory authority asked all the nine companies to tender responses within ten working days, as well as to update it on the actions taken to address the concerns.

FDA commissioner Scott Gottlieb 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. This illegal online marketing of unapproved opioids is contributing to the nation’s opioid crisis.

“Today’s warning letters let online network operators know that marketing illegal and unapproved opioids will not go unchallenged by the FDA.”

“Today’s warning letters go right to the source of this illegal activity to let online network operators know that marketing illegal and unapproved opioids directly to US consumers will not go unchallenged by the FDA.

“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.”

The FDA said that companies failing to correct the violations as instructed in the warning letters may be subject to enforcement action, such as product seizure or injunction.

As part of its efforts to eliminate illicit opioids in the country, the FDA is conducting a summit during which internet stakeholders, government organisations, academic institutions, thought leaders and advocacy groups will meet to discuss approaches to tackle the online availability of illegal opioids.