Stay up to date with our Up First newsletter, sent every weekday morning.
It's a big week for the peptide industry, and the growing number of Americans who've come to embrace the therapies touted for wellness and longevity.
The Food and Drug Administration is convening a panel of outside experts for a two-day meeting starting Thursday to make recommendations on whether compounding pharmacies should be allowed to make some of the most popular injectable peptides.
The gathering of the Pharmacy Compounding Advisory Committee is slated to begin early Thursday morning and stretch until Friday afternoon.
The group will review the evidence for seven compounds, including some of the most sought-after injectables: TB-500, BPC-157 and MOTs-C.
None of them have undergone the kind of large-scale trials to establish safety and effectiveness that are required for FDA drug approvals.
"I see it as very risky," says Paul Knoepfler, a cell and molecular biologist at University of California, Davis who has tracked the upsurge in demand for these peptides, "These are drugs and they haven't been scientifically proven."
Peptide adoption hasn't waited for the science
And yet the therapies have attracted enormous attention in the wellness space, where they're promoted for injury recovery, muscle growth and fat loss, skin health, metabolism and more.
Major direct-to-consumer telehealth companies, med spas and high-end longevity medical practices alike are marketing peptides and their potential.
Proponents argue that the current Biden-era restrictions on compounding of the substances – due to safety concerns and a lack of data — have fueled a grey market of overseas suppliers, raising safety concerns as Americans inject themselves with unvetted substances.
It's a message that industry groups are pushing heavily ahead of this week's meeting.
"When peptides were pulled from the regulated compounding pharmacies, demand didn't go away. It went into the underground," Gary Brecka, a popular podcaster and wellness influencer whose company markets peptides, told reporters during a briefing held by the American Academy of Peptide Medicine, a professional society that formed earlier this year and is advocating for regulatory changes.
"This is not a question of whether Americans will use peptides," he added.
Peptides are strings of amino acids — smaller than a protein — that often act as signaling molecules in our bodies and carry out many critical functions. They can be synthesized and delivered as drugs. Some of those like insulin are naturally occurring in the body. Others are modified versions, as with many of the blockbuster GLP-1 weight loss drugs.
For example, BPC-157 is based on a peptide found in human stomach juices, while TB-500 is related to a molecule found in many types of cells, called thymosin beta-4.
An influential peptide advocate at the top
The upcoming meeting represents yet another tension point between Health Secretary Robert F Kennedy Jr.'s Make America Healthy Again agenda and the traditional medical and scientific establishment.
Kennedy has publicly advocated for lifting restrictions on peptides and talked up their benefits.
In June, the FDA overhauled the roster for the advisory committee. Many of the new members have ties to the peptide industry. Some work for compounding pharmacies or clinics that offer them.
On Tuesday, the agency made further additions, adding a handful of temporary voting members, largely from academic institutions who were designated as having expertise in specific peptides.
FDA officials did not immediately respond to NPR's inquiry about why it had made the changes.
Meanwhile, the FDA's own career scientists are recommending against giving compounding pharmacies the green light to produce any of the seven peptides under consideration.
Sparse clinical evidence versus real-world experience
In a review of the evidence posted ahead of the meeting, they repeatedly note the data comes primarily from preclinical work involving animals — and is quite limited for humans.
For example, there weren't any human clinical studies identified for TB-500. In the case of another compound, Semax, the available evidence "does not establish effectiveness," the document states.
Medical providers should be honest about the "relatively sparse clinical evidence for these peptides," says Dr. Anant Vinjamoori, chief medical officer of Hims & Hers, which plans to offer the peptides if the FDA does reclassify them.
"At this point, we do have experience that's accumulated across close to a decade — thousands of physicians, close to millions of patients — that seems to indicate these peptides can be beneficial to promote health," he adds.
The FDA committee is tasked with reviewing data that supports using these peptides for specific conditions, including migraines, ulcerative colitis, opioid withdrawal and wound healing. However, if the FDA ultimately reclassifies them, clinicians would have discretion to write prescriptions outside of those narrow indications.
While compounding pharmacies can "undoubtedly make better versions of these peptides," UC Davis' Knoepfler says, that doesn't resolve concerns peptides, especially if taken at the wrong dose, could inadvertently promote cancer growth or trigger a dangerous immune response.
But he also worries about the prospect of FDA leadership going against the advice of its own internal scientists.
"I think that's not good for the FDA," he says. " I think that undermines their authority and consistency."
Copyright 2026 NPR