What’s behind the injectable peptide craze?

This is the Guardian. Performing research on yourself used to be something that only fringe scientists and madcap inventors would do. But these are topsy turvy times. And in the world of wellness gurus, longevity bros and Luxmaxers, regulated medicines that have long been proven to be safe and effective are out and cutting edge Experimental drugs are in. The most talked about right now are injectable grey market peptides. Unregulated substances from mysterious sources shot straight into the body.

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These are the two peptides you need

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to be using in 2026. We've got BPC157 which is for healing and tissue repair.

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What if I told that there's a perfect peptide stack to regrow and thicken your hair? Well that would be true because I've done the research so you don't have to.

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And as optimization influencers show off their extreme regimes, tight abs and flawless skin to millions of viewers, more and more of us attempted to turn ourselves into lab rats too.

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I just got a delivery of some peptides. This one is the gloucestack, which I'll be starting after I finish my BPC157 and TB500 pen.

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I've ordered my first peptide, GHKCU. GHK is a peptide that boosts collagen production and it just like enables skin repair. So your skin is nice. If you guys have been curious about peptides hearing about peptides have them on your for you page. This is your sign to hop on a peptide.

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So today, what are peptides and are they really the wonder drugs pharmaceutical companies just don't want you to know about? From the Guardian, I'm Madeline Findlay and this is Science Weekly.

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I think that peptides originated from bodybuilding and workout communities. They're something we've been seeing kind of gradually becoming more popular over, I'd say about the last three years or so. Sometimes people online try to be coy about talking about peptides and you'll see them referred to as peppers.

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Adrienne Matei is a writer who covers lifestyle and wellness for the Guardian US and she's written about the craze for injectable peptides.

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Really the introduction of GLP1s like WeGovy and OzEmpic mainstreamed the idea of injecting yourself with a needle at home and introduced people to the idea of peptides, which The P in GLP1 stands for peptides being associated with almost like magical seeming super fast physical changes that affected their appearance and perceived attractiveness.

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So Adrienne, who's Singing peptides praises. I mean, where would you hear about peptides now?

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There are a few communities or demographics where peptides are getting really popular and one of them is Silicon Valley types. So these are like maybe more risk tolerant youngish professionals who might be into some biohacking or like light transhumanism and who really want to stay on top of tech advancements and have the kind of bragging rights that they're like on the cusp and being fully optimized. And then you have looks maxer guys. So these are the appearance focused young men who we hear a lot about these days who have internalized the belief that they have to be very attractive in a very particular masculine, square jawed, jacked, thick hair sort of way to have value. And of course you have athletes who are maybe using peptides for recovery or a boost in training. And then I've also noticed online you'll see just a lot of middle aged people in forums who are dealing with those kinds of injuries that start becoming more frequent as you approach middle age. Like you know, your neck injuries, tennis elbow, tearing a ligament. And these are people who are just dealing with pain and who want to give anything a shot.

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And they really are giving anything a shot. Because unlike GLP1s, the peptides people are injecting for injuries and recovery, for beauty, for brain fog and for immune support aren't approved regulated drugs that have been extensively in humans. These compounds are often labeled with for research purposes only and not suitable for human consumption. Still, you can find plenty of adverts and special deals for peptides on social media and in encrypted group chats. But where exactly are these drugs coming from? Adrienne?

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They're coming from under the table. China is considered like a hub for a lot of the cheapest peptides on the market. And you'd be hard pressed, I think, to follow the chain of exactly where your Chinese peptides came from, who compounded them in what lab. But we have this U.S. customs data that shows that there were peptide imports valuing 328 million in the first three quarters of 2025, which is double the same period of the previous year. People also get peptides at stateside clinics that would be using local compounding pharmacies to create the peptides they sell. And all are going to be sold with this sort of perfunctory like for research purposes only label. But honestly the only research people are doing is on themselves.

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So what is a peptide? What kind of experiments are people doing on themselves to answer that? I turned to Dr. Anna Barnard, an associate professor at Imperial College London, who researches peptides.

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So, peptides are biomolecules that are made up of building blocks called amino acids. They're assembled in a chain, and that's the same as proteins are. And peptides are shorter than proteins, but they're very interrelated. Peptides can have a number of functions. They can act as signaling molecules, so they can bind to proteins to then elicit a response inside a cell. So angiotensin would be a good example of a peptide that's made in the body. So it's a hormone involved in regulating blood pressure. When it's released, it causes constriction of blood vessels, and that increases blood pressure. And then also other organisms can produce toxic peptides as defense mechanisms. So snakes and snails produce these toxic peptides.

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The grey market for peptides and the public awareness of their medicinal potential may be relatively new. But scientists like Anna have actually been researching and building synthetic peptides in the lab for a long time. And as understanding has grown of what they do in the body and how to target them more effectively, it's become an exciting time for the field.

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It's an enormous field. Basically, there's loads of different mechanisms of action that we can target for drug development. We're working on some peptides that can target cell apoptosis, so that's programmed cell death. And what we want to see if we can do is if we can make peptides that can switch that cell death on in cancer cells so that you can kill the cancer cells and see if we can do that in a sort of way that's less toxic to mammalian cells. And we're also working on some targets in bacteria where we're hoping we can use peptides to potentially wake up bacteria that have gone to sleep in the presence of antibiotics. And if we could use peptides to wake the bacteria up, then the antibiotics might be able to kill more of the bacteria in a single dose, rather than needing multiple doses of antibiotics.

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Other peptides are being designed to break down bacterial cell walls and essentially burst them, as well as to help treat cardiovascular diseases and to prevent inflammation.

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I think that the amount of research that's going into peptides as therapeutics in both universities and in pharmaceutical companies, I'm sure that we will be seeing a peptides entering the clinic in the next decade for sure.

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So these are exciting drugs, but they need to be carefully designed and rigorously tested.

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Anna, there's maybe a misconception that because peptides are something that exists naturally, that therefore they're completely benign. But within proteins, typically in the human body, they're made up of 20 different amino acids. And even if you just have 10 of those in a row, there are billions, trillions of possible combinations that you could have of that. There are more possible peptide sequences than there are stars in the galaxy. And all of those are going to be different individual molecules that behave very differently. Whilst you get a lot of peptides that have very therapeutic benefits, there are probably some that do absolutely nothing. And some of the most toxic substances in the world are peptide based. There's a reason why drugs have to go through all of these kind of regulatory steps is to make sure that they're safe for people to take, make sure that you know how much to take, how often, and what the potential risks versus benefits are.

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And even for synthetic peptides that are identical to what's made in the body, there's no guarantee they'll act in exactly the same way.

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If you're taking something orally, it's going into your stomach, which maybe isn't where it needs to be to have its mode of action. If you're injecting something, it's going into your bloodstream. And it really depends how your peptide behaves in those particular environments that might change how it behaves compared to where it's made naturally. If this starts to go wrong, if there are reported cases of people having really bad side effects, then I think one of the concerns is that it destroys the reputation of people doing research into peptides for genuine benefit. Because then people start to badge peptides as dangerous things and they might potentially reject medicines that are peptide based because of this idea.

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Coming up, risking your health for unproven benefit. How did we get here? Adrienne, as somebody who writes about wellness, you've seen the culture that this peptide craze has popped up in and it seems largely to be tied to this idea of the jacked up wellness bro who's expressing his masculinity through getting bigger and bigger muscles. Muscles optimising his health. I know one of the most popular so called stacks, which is basically combinations of different peptides, is called the Wolverine stack. What's going on here?

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Yeah, there's the Wolverine stack, very enigmatic. And then there's the glow stack, which is sort of like a beautification combination. There are a couple of these things, but I think that the attitude that really threads them all together is this really like YOLO approach to not caring what the consequences are. You have a chance of looking super hot right now. And I think that quick fix attitude has always been in our culture. And this is maybe just one of the first times that it's been enabled by a substance that has this much hype and seeming plausibility. And I feel like it's just that aspect of our culture that the film, the substance was commenting on, like, would you gamble on your health for hotness? And a lot of people's answers are yeah. And, you know, I think that the situation we're seeing with peptides makes sense because people have been told by this administration that, like, they are personally responsible for their health and for the prevention of disease and for their body looking a certain way. And with that pressure, minus reliable tools and trustworthy information, you kind of contribute to the conditions for people to crowdsource on forums to find solutions for their health or ways to promote longevity and to use unregulated foreign drug suppliers they think will be their ticket to better health.

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And that takes us to the U.S. secretary of Health and Human Services, RFK Jr. Now, recently on the Joe Rogan podcast, he said that he would lift a ban on a list of peptides.

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I'm very anxious to move not, probably not all of those peptides, some of them are in litigation, but about 14 of them back to making them more accessible. And within a couple of weeks we will have announced some kind of new action. And my hope is that they're going to end up with. They're still looking at the science. My hope is that they're going to get moved to a place where people have access from ethical suppliers.

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And some have argued that this could make them easier to study. But it's really interesting to me that someone who's expressed public skepticism of pharmaceuticals and vaccines is seemingly more okay with the idea of injecting chemicals with no evidence really of their potential side effects and very little known about their potential benefits.

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Yeah, absolutely. I mean, there is this kind of odd cognitive dissonance, especially when you know what is in vaccines. You know that most vaccines have three, four ingredients in them. And in your average vial of peptides, this is a chain compound between 1 to 100 proteins, plus whatever kind of preservative and compounding material and various incendiaries that you might not ever really be able to establish in this thing. And you're just kind of dropping trow and injecting it into yourself. And it kind of doesn't make any sense. And, you know, I think that it can kind of appeal to this conspiracy mindset that the really good stuff is being withheld from us. To me, I mean, I'm just like, if American pharmaceutical companies felt they could get these drugs approved and viably sell some of these substances, I think that they would be selling them. I think they'd be happy to take your money. And the fact that so many of these substances have not really been studied or their studies have been abandoned or the studies have come out with very marginal effects means that the science there is not setting the world on fire. There's nothing wrong with more research. If the FDA did approve some of these substances, there could be great potential for their use. But for now, just ordering them piecemeal off the gray market is a dangerous thing to be doing.

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Adrienne, you must see health trends come and go, but there are some incredible claims around what peptides can do. Very tempting claims. I think I know what your answer will be after this conversation, but would peptides be anything you yourself would try out?

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Yeah, you know, that's so funny that you ask. You know, someone was just talking to a friend of mine and I feel like it has become kind of just almost regular to imagine that one day you might start using like a GLP1 or some of the peptides that are offering skincare adjacent effects. I mean, they sound very appealing. We are in the habit of doing so much stuff to look after our bodies. And if the kind of promises are true, these things sound like they could be cool to try. But I would never, I think personally have the risk tolerance to order something online and inject it into my body. Especially having seen that some people have reported these side effects that are like full body shingles and anaphylaxis. And knowing that these peptides, you know, we don't know if they increase your cancer risk or if they could speed up the growth of a cancer that you don't even know is in your body. So, you know, if these drugs become fully approved and regulated, I can't rule out that I might not try them out. But with the way things are looking today, I don't think it's quite in my comfort level.

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My thanks to Dr. Anna Barnard and Adrienne Matei. You can find Adrienne's writing on theguardian.com and if you want more essential coverage of health and lifestyle, including practical advice, expert insights and help untangling the wellness world, then I highly recommend signing up for to well, actually a weekly newsletter that lands straight in your inbox. To subscribe, search for. Well, actually from the Guardian and that's it for today. This episode was produced by me, Madeline Finlay. It was sound designed by Joel Cox, and the executive producer is Ellie Burie. We'll be back on Thursday. See you then.

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This is the Guardian.

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