Americans are turning to underground sources for so-called “GLP-3” drugs. Safety, quality, and efficacy still come with a question mark. 

Last week, pharmaceutical giant Eli Lilly announced phase 3 clinical trial results for its big-bet new weight loss drug, retatrutide. The latest company data suggests that, if approved, the still-experimental injection could help users on the highest dose lose up to a third of their body weight over the course of two years, eclipsing the results of Ozempic, Wegovy, Zepbound, and other GLP-1s. 

But there’s a story behind that story. Besides the people actually participating in these clinical trials, everyone else currently taking retatrutide — and there are, apparently, many — is taking a counterfeit version of an un-approved drug, with no promise of safety or efficacy. In a black market network, found mostly online, unverified and unregulated sellers are skirting safety laws to deliver the in-demand injectables. 

Make no mistake: If you’re currently taking a product labeled as retatrutide or “reta,” you should stop taking it. Retatrutide is illegal to sell, and that lack of oversight makes it dangerous.  Compounded peptides like reta can have contamination and sterility issues. You may also not be receiving what it says on the label. And until the drug is approved, we don’t know the full extent of potential side effects and complications associated with using it.

Here’s what we know about the current retatrutide black market, and the potential future uses for an approved version of the drug. 

Who’s Taking Reta?

Late last year, Ian (not his real name), a 32-year old in Australia, weighed in at 194 pounds. Over the previous 18 months, he’d lost 91 pounds, coming down from a high of 285 after a COVID-era leg injury left him sidelined from physical activity. But 194 was not where he wanted to be, and he was frustrated.

“I was stuck. I was sitting at 88-89 kilograms [194-196 pounds], and I was over it. It had been almost two years of slowly dropping all of this weight,” he tells Super Age. To that point, he’d shed most of the weight with exercise and changes to his diet. He added in injectable human growth hormone and a dose of testosterone replacement (prescribed by a doctor) for another boost. But he still wanted to lose more. “I just wanted an extra push,” he says.

To get that push, he turned to a friend who owned a testosterone replacement therapy (TRT) and peptide clinic, and sourced some retatrutide, the so-called “GLP-3” that dieters online can’t stop talking about: If GLP-1s like Ozempic are like a turbocharger on the path to weight loss success, retatrutide fans say the newer compound is like boarding a starship.  

“There was a phase three trial that was published in December that showed 28.7 percent of body weight lost. That’s actually approaching the levels of bariatric surgery, which is a 30 percent weight loss,” says Kevin Gendreau, MD, an obesity physician at Signature Healthcare in Brockton, Massachusetts. 

But, he points out, the drug is still not ready for prime time. “There are like seven active, phase three trials with results expected in 2026 and 2027. So the dosing is really unsure, and the purity of these compounds is also in question because there’s no batch testing of the drug.”

That’s part of why Ian asked us not to identify him by his real name, and why he and other retatrutide users are ordering (still illegal) compounded versions of the drug from peptide clinics and online distributors. Some may receive a tainted product or the wrong product. The reta that Ian ordered worked, he says, but it didn’t convince him that the substance is all positive.

“I think it’s probably the worst thing you can do from an actual health and physical health point of view,” he says, “because you’re not eating. I was force feeding my meals.”

What Puts the “3” In Retatrutide’s “GLP-3” Nickname

There’s a shots-in-arms race in the injectable (and now, thanks to Wegovy, pill-poppable) weight loss drug category, a $2.6 billion industry in 2024. It’s progressing fast. 

These drugs have “transformed the entire medical weight loss landscape,” says Dr. Gendreau. “It’s definitely what patients are seeking as their primary intervention when they come to see a weight loss doctor.” That’s because the drugs seem like miracles, and those miracles keep getting more effective.

The first class of medicines, called semaglutide, are glucagon-like peptide-1 (GLP-1) receptor agonists. You’ve heard of these drugs, but you may not know how they work. Here’s the quick version: Our bodies naturally produce GLP-1 hormones and release them when we eat, boosting the amount of insulin our bodies make to keep blood sugar in a normal range, and making us full after a meal. GLP-1 receptor agonists, like Ozempic and Wegovy, mimic this hormone to stimulate the release of insulin, reduce glucagon, slow stomach emptying, and promote satiety. 

Patients who take semaglutide, Dr. Gendreau says, feel fuller, are more insulin-sensitive, and experience less “food noise.” As a result, they lose weight. In trials, people who took 2.4 mg of Wegovy for 68 weeks lost up to 14.9% of their body weight.

Drugs like Zepbound (tirzepatide) take the active ingredient in Wegovy and add a second — a glucose-dependent insulinotropic polypeptide (GIP) receptor agonist. It’s the same idea as semaglutide, but it works on two different types of receptors. And with the extra ingredient, people lose more weight: up to 20.9 percent over 36 weeks, according to a peer reviewed clinical trial.

Retatrutide adds a third ingredient to the mix, a glucagon receptor agonist. Glucagon is a hormone your body uses to regulate blood sugar levels. It also burns fat.

This third ingredient in retatrutide not only suppresses appetite, but also turns up your metabolism, Dr. Gendreau explains. And that’s led to astonishing results: Eli Lilly announced topline Phase 3 results from the TRIUMPH-4 trial in December 2025 in a company press release, and reta patients lost 28.7 percent of their body weight, an amount that’s consistent with this week’s latest trial, and that approaches the results from bariatric surgery. People taking reta lost that percentage four weeks faster than those taking semaglutide and tirzepatide patients in previous trials.

The Drugs Are Unapproved and Unregulated

Until it’s approved by the FDA — that is, if it’s approved — you won’t get it from your doctor, your pharmacy, or from Eli Lilly itself. 

But with trial results like those, the lack of approval hasn’t stopped patients from asking about the drug, says Ziyad Al-Aly, MD, chief of research and development at the VA St. Louis Health Care System, and a researcher on GLP-1s at Washington University in St. Louis.

“Patients know about it … from TikTok or elsewhere. It’s everywhere,” he says. “But this is not an approved medication in the United States. It’s not available for us to prescribe.”

So patients who hear about reta’s results on TikTok — or on Reddit’s ultra-active r/retatrutide subreddit, which has more than 190,000 users — find ways to get products labeled as retatrutide. They trade links to gray or black market compounding pharmacies that will provide them with the drug at low prices, even though the combo peptide’s purity is not tested. The medication is usually labeled as for “animal or research purposes only.”

Some of these online-ordering reta users, like Ian, are motivated by the promise of unparalleled fat-loss. But Dr. Gendreau says that for others, the calculation is financial: insurance only covers certain FDA-approved meds, or doesn’t cover them at all.

At his practice, he says, some patients will only be approved by insurance for Wegovy, but not the more powerful Zepbound. Or they may reach certain pre-diabetes-related markers that indicate they no longer “need” the medication. (In these cases, it’s not the doctor’s decision whether or not to cease medication.)

While Dr. Gendreau works with patients to adjust their lifestyle and use what fits with their monthly co-pay, it’s not hard to imagine a patient who still wants weight loss or maintenance support and turns to online sources for what they see as a powerful fix.

What You Lose Besides Weight

Losing 30 percent of your body weight sounds like an incredible result, and for some patients, it may be life-changing. But not all weight loss is equal, says John Batsis, MD, Associate Professor of Geriatric Medicine at the University of North Carolina School of Medicine.

“When you lose weight, you lose fat, but you also lose both muscle and bone,” he says. “When you lose a precipitous amount of weight, and particularly when you’re losing it quickly, what ends up happening is that you can have a negative effect on muscle mass and muscle function. And that, in itself, can lead to frailty, disability, and the like.”

This could be especially dependent on diet quality, Dr. Batsis and Dr. Gendreau say. Ian was laser-locked on his protein intake and other macros while taking his version of reta, but not all patients on injectable weight loss drugs focus on nutrition. GLP-1 patients tend to eat fewer processed foods, but they still desire them, scientists say. And some people taking these medications save their limited appetites for their favorite high-calorie foods.

With a drug as powerful as retatrutide, this could lead to nutrient deficiencies, Dr. Batsis says. This is why, Dr. Gendreau says, working with a doctor who specializes in weight loss can keep patients safer. His patients receive not only weight loss drugs, but also nutrition counseling that helps them eat the nutrients they need for healthy organ function, and stronger muscles and bones.

A Hidden Risk: Drug Interactions

Dr. Gendreau points out another potential consequence of taking reta: drug interactions with other medications you’re taking.

“One of the biggest things is that we know in studies, retatrutide is reducing known markers for cardiovascular risk, including non-HDL cholesterol and triglycerides. Systolic blood pressure is lowering,” he says.

These are promising results, but if you’re not talking to your doctor about taking reta — and you’re already taking a blood pressure- or cholesterol-lowering medication — these additional reductions could make the medicines you’re already taking dangerous, he warns. “What if your blood pressure tanks and you’re passing out, because you’re on three different drugs for your blood pressure that you no longer need?”

For people taking reta now, its ingredients and doses unverified, the drug could literally interact with anything. You don’t know what’s in it, or how much. 

The Surprising Side Effects Worth Considering

Another risk that remains unknown with gray or black market meds: side effects. 

While some reta users have reported positive side effects — Ian, like some others, says it’s helped calm ADHD symptoms. Others are less lucky, reporting dry skin and skin hypersensitivity, sulfuric burps, flatulence, and diarrhea. As part of its increase in metabolic activity, reta also increases heart rate slightly, though this has not been connected to adverse cardiovascular events at this time. It also causes mental effects. Specifically, reta users have reported increased “anhedonia,” a medical term for no longer enjoying the things you previously enjoyed. 

Dr. Al-Aly is studying this effect from GLP-1s at Washington University in St. Louis. His research has shown that the GLP-1 molecule can cross the blood-brain barrier, and can reduce our cravings not just for food, but for stimuli in general. His research has shown that GLP-1s can reduce cravings for addictive harmful substances like cigarettes and drugs, but they may also lower drive or desire more generally. There’s still more to learn about how more powerful drugs in this class can impact people’s reward systems. But some retatrutide patients have said, anecdotally, that they feel listless and without purpose or drive.

That’s not stopping Lilly, the pharmaceutical company behind Zepbound and reta, from continuing to push for approval. And it’s not stopping users online from scrambling for new sources of cheap vials of the peptide complex.

If it’s approved, Dr. Batsis believes, the super-effectiveness of this drug may require clinicians to think about weight loss in new ways.

“These are really promising medications. We’re getting more and more data, but it’s not all about the weight,” Dr. Batsis says. “And you have individuals that may benefit from a certain amount of weight loss, and others may only benefit from a smaller degree of weight loss… Yes, you can lose X percent of your weight, but you need to maximize your function, quality of life, and metabolic profile.”

Ian agrees. Kind of. 

He’s still taking something labeled as reta, despite viewing it as the “worst thing you can do for your health.” He’s now sourcing the triple peptide directly from a Chinese supplier. The 32-year old already looks fit, kind of like an MMA fighter on a cut. He’s down to 180 pounds. Soon, he says, he’ll do a “health phase,” prioritizing maintenance over loss.  

But the progress is addictive: he wants to lose just a few more before he quits.

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