Just under three years ago, the Food and Drug Administration deemed 19 peptide drugs too unsafe to be dispensed by compounding pharmacies, which mix components of approved drugs to create bespoke medication for people who have trouble taking commonly available products.

Now, under Health and Human Services Secretary Robert F. Kennedy Jr., the agency is poised to reverse itself. That’s despite few clinical studies supporting the effectiveness or safety of these peptides, which are amino acid chains meant to help regulate functions in the body and have become popular among fitness and longevity enthusiasts.

In February, Kennedy said the FDA acted illegally in 2023 when it categorized 19 peptides as too unsafe for compounders, whose final products aren’t tested or approved by the FDA. Kennedy, who described himself as a “big fan” of peptides, has used the therapies himself.

“It was illegal because they’re not supposed to do that unless there’s a safety signal,” Kennedy said on “The Joe Rogan Experience” podcast, referring to adverse events related to medications. “And they didn’t have a safety signal. They’re not allowed to look at efficacy. They’re not allowed to say, ‘Well, we don’t believe these are efficacious,’ or whatever. They can only look at safety.”

But three former FDA officials closely familiar with how the agency created the criteria to assess the peptides in the first place say Kennedy has mischaracterized their work. The agency’s 2023 decision to ban certain peptides was supported by numerous documented safety concerns, they said. FDA regulations also require the agency to assess both safety and effectiveness before approving a substance for compounding.

“It would be a disruption of the societal pact we have had since 1962 that drugs will be studied to see if they work before they are marketed in the U.S.,” said Janet Woodcock, a former FDA acting commissioner.

If Kennedy justifies reversal of the previous work by suggesting there were no safety concerns, it would give a false imprimatur of safety to more than a dozen unapproved, untested drugs, the officials said.

There’s been little new science on the 19 peptides since the FDA’s 2023 decision to categorize them as unsafe. But demand for the drugs has exploded as influencers have flooded social media with promises of sculpted physiques, glowing skin, luscious hair, rapidly healing injuries, youthful energy and blazing sex lives.

The demand has given rise to a burgeoning gray market, where wellness spas, multilevel marketers and telehealth websites ply the public with vials of “research grade” peptides labeled “not for human use.”

“More people want to use them,” said Lauren Colenso-Semple, a muscle physiology researcher and science communication specialist who follows scientific studies of peptides as part of her work. “That’s what’s changed.”

FDA-approved peptide drugs such as insulin and oxytocin have been available for decades. Newer ones such as semaglutide and tirzepatide, broadly known as GLP-1s, have exploded in popularity for weight loss and have shown promise for treating other conditions, such as addictions and neurodegenerative and liver diseases. The popularity of these drugs has led the public to become more comfortable with injectables and has helped drive attention to other gray-market peptides.

Last year, at a Las Vegas conference promising radical life extension, two women became critically ill after being injected with peptides the FDA had categorized as unsafe. Although Nevada regulators investigated and fined the health practitioners involved in administering the peptides, investigators weren’t able to determine the exact cause of the reaction. The doctor who ran the booth where the women became ill said he didn’t believe that the peptides caused their reactions but apologized for the incident and said he would review his practices.

The Alliance for Pharmacy Compounding, one of the largest industry associations lobbying for the FDA to change its stance on peptides, acknowledges it knows little about the safety of individual peptides being sold to the public. (Its CEO says it is an advocacy organization, not a scientific one.) But the group argues the public would be safer if peptides were handled by regulated compounding pharmacies instead of the gray market. The FDA should forgo the usual human clinical trials in order to bring about this shift, a spokesperson for the alliance........

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