Why Unapproved Peptides Are Risky
Key takeaways:
- Many important molecules in the body are peptides. Some peptides, like GLP-1, can be modified into effective medications for a variety of conditions, including diabetes.
- Recently, health, wellness, and fitness influencers have been touting the benefits of unapproved peptides that are often sold “for research purposes only.”
- If a peptide has not been approved as a medication, then taking it can be risky and potentially ineffective.
For people outside of the diabetes community, it probably seemed weight management drugs like Wegovy (semaglutide) and Zepbound (tirzepatide) came out of nowhere. All of a sudden, it was possible to buy truly effective weight loss drugs that offered a whole host of other benefits. In that sense, it’s easy to see why GLP-1s – which belong to a class of molecules called peptides – have generated so much hype.
But people with diabetes know that the latest GLP-1 drugs did not come out of nowhere. Drug developers have spent years experimenting with different molecules and rigorously testing them in clinical trials to make sure they are safe and effective for people using them.
Right now, there is a lot of interest in the potential health benefits of peptides that have not been approved as medications, and companies that technically make these unapproved substances for research purposes are selling them to people who may have heard about them on health, wellness, and fitness podcasts or seen posts about them on social media. These informal advertisers often tout the (unproven) benefits and low costs of their preferred experimental peptide. While it’s possible that unapproved peptides may be effective for at least some of the people who try them, taking them is a risk.
What are peptides?
Peptides are small chains of amino acids, which are also the building blocks of proteins in food and the body. When you eat, your body breaks protein down into individual amino acids and then uses those pieces to build whatever molecules it needs at that moment.
There are peptides that promote wound healing, regulate inflammation, and enable communication between neurons in the brain. That’s why these molecules generate a lot of interest from the pharmaceutical industry.
Synthetic versions of insulin, glucagon, and GLP-1 are essential medications that help people with diabetes manage their blood sugar. These are just some of the peptides that have been approved as medicines for various maladies, including infectious diseases, chronic conditions, and cancer.
Some peptide drugs are identical to molecules that our bodies make, and others are slightly modified to be more effective. Weekly GLP-1 injections work because researchers learned how to make the molecule last longer by studying a version of it found in the saliva of Gila monsters.
Peptide drugs may also be modeled on molecules that other living things make, but we do not. For example, many ACE inhibitors, which are used to treat high blood pressure, are based on a molecule found in the venom of the Brazilian pit viper. The synthetic versions of these peptides are given at low enough doses that their benefits far outweigh the side effects.
So far, the FDA has approved over 100 peptides as prescription medications, and there are many others that are currently being developed and tested.
“There may be more peptides out there that we haven’t yet tested with really important health benefits,” said Dr. Dan Drucker, an endocrinologist and professor of medicine at the University of Toronto.
However, only some of the molecules classified as peptides affect the human body, and only some of those can be safely taken as medicine. Figuring out which peptide drugs are effective and how to take them safely requires careful research and clinical testing.
Why unapproved peptides are risky and potentially ineffective
Before any molecule – whether it’s a peptide or something else – can be approved as a drug, someone must demonstrate that it is safe and effective for human beings to use.
Why they may be ineffective
A peptide might be ineffective for a variety of reasons. Some combinations of amino acids just don’t interact with anything in the human body. Others are filtered out as waste or broken down into parts so quickly that they may not produce a meaningful change in the body.
Even if a peptide interacts with the body and lasts long enough to make an impact, there’s no guarantee that it will end up where it needs to go. For instance, if you take a peptide as an oral drug, it might never make it out of the stomach. And an injectable peptide designed to improve brain health might have no way to cross the blood-brain barrier.
The only way to be sure that a peptide drug goes where you want it to go and does what you want it to do is to test it out on a large number of people in controlled clinical trials. Unapproved peptides generally have not been tested in this way.
“At best, some of them have been tested in a few dozen people,” Drucker said. “At worst, they’ve never really been tested in people. They’ve only been tested in animals. So, it’s a bit of the wild west out there.”
Why they may be unsafe
Unapproved peptides could work as intended, but they might not be safe for everyone to take. In fact, two women who received anti-aging peptide injections in Las Vegas in 2025 became so ill that they had to be hospitalized, although it wasn’t immediately clear what ingredients or contaminants were responsible.
Because their effects on people are not being documented in formal studies, it’s hard to know what types of harm unapproved peptides cause or whether these harms could be avoided by preparing and taking the drugs more carefully.
Large clinical trials provide an opportunity to identify a potential drug’s side effects and see how common and severe they are. Sometimes, severe side effects – such as life-threatening allergic reactions, increased risk of infections, or harmful interactions with other drugs – don’t reveal themselves until very late in the drug development process, when many different people have taken it. Furthermore, the risks associated with long-term use, which may include higher chances of cancer and worsening of heart, liver, and kidney health, cannot be properly assessed until people have taken the drug and monitored their health for extended periods of time.
Ideally, these trials include a diversity of people who represent different genders, ethnicities, and age groups because different bodies can react to the same molecule in different ways. Just because someone you know has taken an unapproved peptide without any issues doesn’t mean you won’t have a bad reaction.
So, even if an experimental peptide, like retatrutide or cagrilinitide, for example, has demonstrated safety and efficacy in early clinical trials, it’s still a good idea to be cautious if it hasn’t been officially approved yet.
Researchers also use trials to figure out the proper dose for a drug. Any medication can become a poison if you take too much of it, and if there’s no data from clinical trials, then people are guessing when they decide how much of an unapproved peptide to take.
Additionally, companies that sell unapproved peptides for research use only don't face the same legal obligation to minimize the risk to people who take them, so they are less likely to put their products in easy-to-use injector pens or provide thorough instructions. People who take unapproved peptides and compounded GLP-1 products are more likely to overdose because the instructions might not be clear, or they have never mixed a solution or drawn it up in a syringe.
It’s also important to note that companies that sell unapproved substances are not subject to the same safety regulations as pharmaceutical companies. To sell medicine, companies have to demonstrate that they have sterile facilities that follow good manufacturing practices. They have to publicly disclose the active and inactive ingredients in the shots and pills that they make, and they have to verify all of those ingredients. They also need to be able to tell their customers how to store their product and when the product expires.
“If I make a peptide on May 6, 2026, and I put it on the shelf, is it still what I think it is three months later? Six months later? A year later?” Drucker said.
Companies that are selling things that aren’t legally defined as medicine face less scrutiny, so if you buy an unapproved peptide online, there can be many more unknowns concerning what’s in the bottle that ultimately arrives in the mail. A company that tests peptide products found that 8% of the samples they received were contaminated with dangerous bacterial toxins.
The bottom line
Some peptides, like GLP-1s, have proven to be very effective medications, and there are many peptides that may prove to be effective medications in the future. But without clear evidence from large clinical trials, there’s no way to be sure any health claims around unapproved peptides outweigh any harm that they may cause.
“It’s not worth taking chances with your health for a potential but not proven benefit,” Drucker said. “Just be careful out there.”
Learn more about approved diabetes treatments and safety risks here: