DIY peptide injections are risky, and people may make serious mistakes when administering them

DIY peptide injections, which promise to boost everything from weight loss and muscle-building to longevity and sexual health, are a high-risk wellness fad that keeps on growing.

Health experts have raised major concerns about these products’ safety. Because they are not regulated by the U.S. Food and Drug Administration or any other health authority, they aren’t made to the standards of pharmaceuticals. They could have bacterial, fungal, chemical or heavy metal contamination; their purity could be lower than indicated; and the dose promised may not be what you receive.

In July 2026, the CEO of one peptide company was sentenced to 70 months in prison for selling tainted and substandard products.

However, the dangers don’t end there.

I’m a pharmacist and clinical pharmacologist who has been studying the emerging gray market for peptides – where companies use legal loopholes to sell unapproved products to consumers. In addition to the potential harm from these products’ possible impurities, people who purchase peptides from this online gray market are likely to make lots of mistakes when injecting them, my colleagues and I found in a new study published in the journal Public Health Reports.

Many of these mistakes can result in serious harm.

Access without guidance

Consumers can purchase all sorts of peptides online – such as versions of the weight loss drug semaglutide, compounds like BPC-157 and TB-500 for fitness and muscle recovery, or one called Semax for purportedly sharpening cognition. They can inject them into their bodies, as long as they check a box saying the product will be used “for research purposes.”

It is illegal for peptide companies to give consumers any information about how to safely use their products, because if they did, the FDA can say they knew people were not using them for research purposes. This means consumers must purchase any supplies they need and figure out the proper technique on their own.

User errors abound

To see whether consumers are up to the task, we recruited 10 college students who were in the 20-year-old range, and 10 adults in their 60s, and gave them each a vial of a semaglutide GLP-1 peptide product. We asked them to demonstrate how to correctly dissolve the semaglutide powder, draw it up into a syringe and inject it into a mannequin’s arm or belly. Before doing so, they could use the internet or artificial intelligence to do research and take any notes they wanted.

In both groups, on average, people did fewer than half the steps correctly. Some participants chose vials with liquid to dissolve the semaglutide powder that were expired, had floating particles in them or were cloudy. Many people struggled to determine how much liquid to add to dissolve the powder and the correct dose to draw up once it was dissolved. Several struggled to get rid of large air bubbles in the syringe, which can cause injection site irritation and make dosing inaccurate.

Some people injected the peptides into muscle instead of the arm or belly fat, which could alter how quickly the drugs reach the bloodstream. Many people didn’t sterilize the vials or the skin before injection. They had trouble deciding how long the products could be used before they expired. Finally, half of the people struggled with how to engage the safety features on the needles and properly dispose of them.

These errors were serious and could increase the risk of infection, bleeding, over- or under-dosing, and needle sticks.

Overconfidence may add risk

Such user errors are an underappreciated danger of using these substances. What’s more, our findings suggest that some users may be overconfident about their ability to inject peptides.

In our study, after participants did their online research, most people in both groups said they were somewhat confident they could do the injections competently. Even after struggling through the injection process, participants in the younger group remained somewhat confident that they could do it right next time. Meanwhile, the older adults’ confidence dropped, aligning with previous research showing that older adults are generally better able to gauge their ability to perform complex tasks.

Our study only included 20 people, all from the Northeast U.S., and we only assessed one peptide. But we believe the findings apply broadly, across many types of peptides, based on our and others’ experience counseling patients about properly drawing up and injecting other drugs, such as insulin.

That is why companies are moving to special pens to make injecting prescription GLP-1s and insulin less complex for untrained people.

Can compounding make peptides safer?

In late July 2026, an advisory panel convened by the FDA recommended that the agency add six widely used peptides – including BPC-157, TB-500 and Semax – to a list of substances that can be formulated and sold by compounding pharmacies.

These specialized pharmacies, which combine raw drug ingredients to create custom medicines, generally provide unique dosage forms for people with special needs. None of the six peptides are FDA-approved, but compounding pharmacies already provide some peptides like semaglutide, which are FDA-approved, for people with special needs.

The advisory panel members argued that peptides obtained from compounding pharmacies would be safer than buying them on the gray market because compounding pharmacies have rules about safe sourcing and testing and must maintain sterile environments where products are made. Plus, patients could receive compounded products that are much easier to administer, and compounding pharmacies can provide supplies, information and support for patients to use them correctly.

The FDA has not said whether it plans to adopt these recommendations. But even if it does, the recommendations apply to only a small handful of such products that consumers can purchase, and they don’t address the fact that these products are not tested for safety or efficacy. So the many safety issues relating to gray-market peptides would remain a significant concern.