The Mr. Green bodega sits on a busy stretch of Bedford Avenue in Brooklyn, New York. Near the counter, you can buy the usual assortment of candy, gum, rolling papers, and soda. You can also purchase tiny vials of injectable peptides. So we did. And then we sent them to a lab.

Mr. Green is one of several shops that went viral this summer for selling peptides, a broad class of amino acids touted for their ability to aid in everything from weight loss to injury recovery. For $376.20, we acquired four varieties: PT-141, for low libido; BPC-157, for healing and muscle recovery; NAD+, for cellular repair; and retatrutide, for weight loss. The clerk packed them up in an unlabeled paper bag and sent us on our way.

WIRED sent the vials to Finnrick, an Austin-based startup that offers independent peptide testing. Consumers can request tests for purity and whether samples contain common contaminants, as well as whether they contain the quantity of the substance listed. The company doesn’t have in-house labs but instead acts as a middleman between labs and individuals. In a few weeks’ time, Finnrick told us, we’d know if our bodega peptides were the real deal.

In August, the results came in. The (relatively) good news: The samples contained low levels of heavy metals and endotoxins, meaning they likely weren’t actively harmful. The bad news: They weren’t peptides.

The testing for each substance found that they did not contain the active ingredients on their labels—the BPC-157, for example, had no BPC-157 within it. The negative results suggested that the vials were either mislabeled or, if they had at one point contained the correct ingredients, had been corrupted beyond recognition. Peptides are often sensitive to temperature changes and require refrigeration, so improper storage could degrade ingredients, for example.

What did they contain? Hard to say, according to Marco Krause, the chief executive officer of the laboratory that performed the tests for Finnrick.

“What we offer is simply a label claim analysis. So you send us what you claim to think it is, and then we run it against a standard and verify whether or not it’s the right compound,” he tells WIRED.

Peptides have surged in popularity in recent years, powered by endorsements from figures like US health secretary Robert F. Kennedy Jr. and podcaster Joe Rogan. While some of these substances are pharmaceutical drugs like GLP-1s and insulin, many of the buzziest peptides have not been put through the typical regulatory approval process for drugs. Despite the hype surrounding them, many of these substances are not legal to sell for human consumption in the US—some precisely because they haven’t gone through the drug approval pipeline—and evidence of their purported benefits is thin.

The sign at Mr. Green advertising the peptides noted they were for “research use only,” a term that labs can use in an attempt to shield themselves from legal liability. But as the test results show, there’s no guarantee what’s in the vials—and in some cases there are real dangers to those taking them.

According to Raphaël Mazoyer, Finnrick’s CEO, the samples WIRED tested appear to be “just duds.” Over the past three months, Mazoyer says, the company has seen an uptick in these kinds of results. Though he can’t say for certain what’s going on—in part, his company has been testing more samples as it has grown—he points to the popularity of so-called turnkey services, which help pretty much anyone open a peptide business.

“There are a whole bunch of labels popping up that have the same upstream vendor,” he says. Not all the peptides Finnrick tests are duds, but the nature of the industry means that businesses may use the same shoddy supplier across a number of different brands.

WIRED isn’t the only organization to receive abnormal lab results after sending in peptides sold over the counter. Jeff Colhoun, the founder of the research-peptide vendor directory Peptide Critic, purchased INDR Labs peptides from a smoke shop down the street from Mr. Green called Smoker’s World and sent them to a different independent laboratory for testing.

Colhoun purchased two vials of retatrutide and two vials of NAD+ and had all four analyzed by Texas-based Analytical Formulations. The lab could “not positively identify” the substances. This doesn’t mean that they didn’t contain any of the substances listed, but it does suggest that the samples may have been contaminated or were otherwise too corrupted to decipher what was in the vials.

Colhoun says that he has heard from research-peptide vendors who have had similar results while testing products prior to selling them, and notes that buyers are at a high risk level when sellers “skip meaningful batch testing” altogether.

INDR Labs did not respond to WIRED’s request for comment, but shortly after we reached out, its website began requiring login credentials. It previously cut off public access to its certificates of analysis, which provide evidence that a product has met certain standards. The company claimed its certificates were provided by Vanguard Laboratory; a spokesperson for Vanguard denied issuing the paperwork, CBS News previously reported.

INDR Labs is just one part of this booming ecosystem that investors estimate is already worth up to $3 billion, according to reporting from Bloomberg News. While the FDA has taken recent steps to loosen regulations, and many large telehealth platforms like Hims and Mochi are preparing to start selling a broad array of peptides, many people who take these substances today are purchasing them through questionable channels.

“The FDA needs to shut down these black markets,” Fred Mills, a longtime pharmacist and an executive at the nonprofit Americans for Safe and Effective Medicines, tells WIRED. Mills, who is based in Louisiana, says he’s had discussions recently about the dangers of people purchasing peptide products at convenience stores and that he warns those who do so to consult with a physician first.

If a peptide vial actually contains little more than water or saline solution, the worst that might happen is that someone loses money on a useless product. But some mislabeled peptides can contain ingredients that cause harm; a woman died this year after receiving a peptide injection from an unlicensed medical spa in the Bronx.

“My concern with the peptide industry is, we’re legitimizing products, and we have no idea what’s in them. We have no idea about the safety, accuracy profile, or whether they’re adulterated or misbranded,” says Darshan Kulkarni, an attorney focused on pharmaceutical regulatory compliance. In the traditional pharmaceutical sales world, steps are taken to ensure prescription accuracy and product safety, from visual inspections to barcoding.

“Someone selling a product at a bodega doesn’t know how to do that,” Kulkarni says.

“The FDA has warned companies selling products labeled ‘for research purposes’ or ‘not for human consumption’ when those products are marketed directly to consumers for human use,” an agency spokesperson who declined to give their name tells WIRED in an email. “Additionally, the FDA has warned telehealth companies for marketing drugs directly to consumers and for making false or misleading claims regarding compounded GLP-1 products offered on their websites. The FDA will continue to take action, where appropriate, to protect public health.”

The agency did not answer WIRED’s questions about whether it has contacted or taken enforcement action against brick-and-mortar sellers of peptides labeled research-only, like those sold by Mr. Green.

There have been some enforcement actions. Earlier this summer, a man in South Bend, Indiana, was sentenced to six years in prison for selling “research use” peptides that were illegally imported from China—a major source of peptide ingredients—and were adulterated with steroids. Still, the enforcement atmosphere is loose enough that it remains easy to buy unapproved peptides both online and at brick-and-mortar medspas and other locations.

Kulkarni believes that the relatively low number of enforcement actions taken against the research peptide industry is related to the Trump administration’s attitude that “regulation stifles innovation, and therefore they believe that it is in the interest of patients to allow them to decide what products to take.”

As for Mr. Green, it did not respond to a written list of questions provided by WIRED. When we visited in early September, the menu in the window was gone. But a smaller version was next to the counter, and the peptides were still for sale.

Additional reporting by Caroline Haskins.