Federal authorities are investigating Meta Platforms for its role in the illicit sale of drugs, according to documents and people familiar with the matter.

U.S. prosecutors in Virginia have been sending subpoenas and asking questions as part of a criminal grand jury probe looking into whether the company’s social-media platforms are facilitating and profiting from the illegal sale of drugs, the people familiar with the matter said. Meta is the owner of Instagram and Facebook.

The prosecutors have requested records related to “violative drug content on Meta’s platforms and/or the illicit sale of drugs via Meta’s platforms,” according to copies of subpoenas reviewed by The Wall Street Journal. The subpoenas were delivered last year.

The Food and Drug Administration has been helping with the investigation, the people familiar with the matter said. Investigations don’t always result in formal charges of wrongdoing. The prosecutors’ office and a spokeswoman for the FDA declined to comment.

“The sale of illicit drugs is against our policies and we work to find and remove this content from our services,” a spokesman for Meta said in a statement. “Meta proactively cooperates with law enforcement authorities to help combat the sale and distribution of illicit drugs.”

On Friday, Nick Clegg , Meta’s president of global affairs, said the company has joined an effort alongside the State Department and others to help disrupt the sale of synthetic drugs online and educate users about the risks. “The opioid epidemic is a major public health issue that requires action from all parts of US society,” he wrote in a tweet.

Meta has enlisted outside entities to screen advertisers and content that might violate rules regarding the promotion and sale of drugs. A company called LegitScript helps determine which companies can advertise and promote prescription medication on its platforms. Researchers at the University of Alabama at Birmingham had a partnership with Facebook to help flag problematic content related to drug sales. A spokeswoman for the university said it isn’t a current service provider for Meta.

Social-media companies have recently come under scrutiny from members of Congress for content that has harmed young people, particularly children.

Lawmakers have been discussing the need to hold the technology companies responsible for what third parties post on their platforms. Efforts to do so have been complicated by Section 230 of the Communications Decency Act , which says that online platforms aren’t liable for what third parties post, with a few exceptions . The Supreme Court left core elements of Section 230 unchanged after deciding on two cases involving the law in 2023.

The Justice Department in the past has tried to extend the reach of federal drug laws to make an internet platform culpable when companies use it to break the law. In 2011, Google agreed to forfeit $500 million for allowing online Canadian pharmacies to place ads targeting U.S. consumers, resulting in the unlawful importation of prescription drugs in the U.S.

Gretchen Peters, executive director of the Alliance to Counter Crime Online, confirmed that her organization had received a federal subpoena in the Meta investigation but declined to comment further.

As part of the investigation, prosecutors also subpoenaed the Algorithmic Transparency Institute, a project of the nonprofit National Conference on Citizenship, for research related to violative drug content on Meta Platforms. A special agent from the FDA’s criminal-investigations division delivered the subpoena, said Cameron Hickey, the conference’s chief executive. The group turned over to prosecutors thousands of telehealth company ads from Meta’s ad library, many featuring prescription drugs, which researchers collected at the request of the Journal in 2022, Hickey said.

During the pandemic, such telehealth companies flooded Facebook and Instagram with ads touting prescription drugs for the treatment of attention-deficit hyperactivity disorder, anxiety and other medical conditions. Employees and patients said in interviews that the ads contributed to the abuse of controlled substances such as Adderall.

A Journal investigation in 2022 highlighted telehealth companies’ ads that touted benefits of medications with no mention of side effects and promoted drugs for uses that weren’t approved by the FDA—skirting traditional FDA advertising rules. The FDA has typically limited the scope of its regulatory authority to packers, distributors and manufacturers of prescription drugs. The telehealth companies told the Journal that they aren’t subject to FDA rules because they are medical providers—not the manufacturers, packers or distributors of the drugs.

Sellers have recently advertised counterfeit versions of blockbuster weight-loss drugs on Meta’s platforms, including one drug that is still at least two years away from receiving FDA approval, the Journal has reported. Meta took down some of the ads that were flagged by the Journal, but in some cases, nearly identical ones popped up soon after.

Assistant U.S. Attorney Randy Ramseyer, who previously investigated Purdue Pharma’s marketing of OxyContin, requested the subpoenas. Ramseyer was featured as a character in the Hulu miniseries “Dopesick,” about the opioid crisis in the U.S. Ramseyer works in U.S. Attorney Christopher Kavanaugh’s office.

Last month, a bipartisan group of senators sent a letter to the FDA , requesting that the agency take action against the marketing of prescription drugs on social media, citing the Journal’s previous reporting about telehealth company ads promoting easy access to prescription drugs.

A Journal investigation in 2021 found that TikTok served minors thousands of videos containing drug and other adult content; TikTok didn’t respond as to whether it also received a subpoena.

Write to Andrea Fuller at andrea.fuller@wsj.com , Salvador Rodriguez at salvador.rodriguez@wsj.com and Khadeeja Safdar at khadeeja.safdar@wsj.com