Search the term "peptides" and a long list of online retailer options will pop up. You'll be offered vials of molecules with funky names that sound like exoplanets: GHK-CU, CJC12-95, Thymosin Beta-4.
These synthetic peptides are growing popular among biohackers and wellness influencers. They take them, often via injection, in hopes they'll enhance athletic performance and optimize health.
Among scores of enthusiasts online, fitness TikToker Noah Jay claimed in a recent video that the peptide BPC-157 healed his shoulder injury: "I absolutely love this stuff!" Like many influencers talking up peptides, his profile links to a discount code for an online retailer.
(NPR reached out to Noah Jay through his TikTok and Instagram accounts for comment and to ask if he receives any income from the peptide sales, but did not receive a reply.)
But there are risks when using substances that aren't approved by the Food and Drug Administration for human use. Here's what doctors and scientists say about the trend.
The claim
Various synthetic peptides stimulate natural biological processes that can improve one's health and appearance. Different peptides have different claims but some of the most popular ones are: muscle growth, better immune function and slower aging.
The evidence
Peptides are chains of amino acids. There are millions of them in the human body. Some signal your body to do important things like regulate immune function, grow certain cells and control hormones.
There are well-known synthetic peptides that are FDA-approved, effective medicine. Insulin is one, as is the active ingredient of GLP-1 obesity drugs.
But many of the other peptides you can buy are, at best, experimental, and their purported benefits are unproven.
Most of the research has been in animals or labs, not humans, says Paul Knoepfler, a cell and molecular biologist at University of California, Davis. Depending on the peptide and its application, the science can make theoretical sense, he says, but Knoepfler warned that using an untested peptide could cause serious harm.
For example, some animal studies suggest BPC-157 helps with tissue repair because it accelerates the growth of new blood vessels. Knoepfler cautioned that this peptide could theoretically also encourage the growth of precancerous cells.
"You must test these in clinical trials to be sure of anything positive or negative," he says.
Knoepfler also notes that the same substance that's helpful at one dose might be ineffective or even harmful at another dose.
"You can't just make up what dose to take," he says. But without further research, the therapeutic dose is unknown. "There's often no apparent rhyme or reason to the wellness peptide doses people are taking," he adds.
Anyone determined to try them should consult a physician, Knoepfler says.
Some are open to alternative approaches. And it's better to talk to a doctor than pretend you're one yourself, agrees Howard Sklamberg, a former FDA deputy commissioner. "At least if you're talking to your doctor, you're talking to somebody who can, theoretically, be held accountable."
Dr. Amanda Kahn runs a concierge medical practice in Midtown Manhattan and says many of her patients come to her seeking second or third opinions for issues like inflammation or chronic pain. Kahn says in some instances the popularity of peptides has outpaced the science, but she will prescribe them as an "adjunct" therapy if she thinks it's appropriate.
She told NPR that she makes sure patients understand that these drugs are experimental. "I don't overpromise that this is a cure-all," she says.
The marketplace
Some people are buying and injecting peptides without a doctor's involvement, purchasing them from online sellers. This includes research-grade peptides, which state on the label they're not for pharmaceutical use.
But Kahn and Knoepfler warn that these products could include solutions or contaminants that are toxic, and they say people should not purchase peptides without consulting with a physician.
Doctors who prescribe them generally send patients to compounding pharmacies. These are specialized pharmacies that can prepare tailored versions of drugs for individual patients.
Peptides that aren't FDA-approved — including many of the popular ones touted by influencers — can't be obtained from a normal pharmacy.
Part of the problem is that, with some exceptions, these pharmacies aren't regulated the same way as drug manufacturers, and that can make compounded products riskier, says Sklamberg.
"That's been a longstanding challenge for FDA for many years," says Sklamberg, who added that when compounding pharmacies produce large quantities of a medication, quality control is more of a concern.
Scott Brunner, the chief executive officer of Alliance for Pharmacy Compounding, says compounding pharmacies are licensed and inspected by state boards of pharmacy. This regulatory framework isn't weaker, just different, he argues.
"The oversight is rigorous and appropriate for a pharmacy making one drug for one patient" that's been prescribed by a doctor, he says.
In an email statement, the FDA told NPR that it is working to develop lists of bulk drug substances that can be used in compounding. Currently, certain peptides are on an FDA list of substances with "significant safety concerns."
And it's risky to purchase peptides that are marketed as supplements. Sklamberg says these products could be viewed as unregulated drugs, though the volume of online retail makes it difficult for the FDA to go after every bad actor.
When it comes to peptides, "it's really kind of a Wild West," he says.
Bottom line
Some of the popular peptides marketed online might have potential health and wellness benefits. But most haven't been well studied for efficacy and safety in humans, so taking them is a gamble.
Consulting a physician and purchasing peptides from a compounding pharmacy can mitigate some risk. Still, these drugs are experimental, and the long-term health consequences are unknown.
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