On social media, peptides sound like miracle products. These injectable drugs, made from combinations of amino acids, promise benefits from muscle growth and weight loss to tanner skin and slower aging.

But a recent criminal case underscores the concerns some experts have been raising for months about the unregulated medications. In late July, a peptide seller was sentenced to nearly six years in prison for deceiving customers and selling mislabeled products.1

The news comes as the Food and Drug Administration is considering easing restrictions on seven peptides. Currently, the only way to obtain unapproved peptides is through online vendors selling the products for “research use only.” But just before the sentencing, an FDA advisory committee recommended making six of them available for compounding, including the popular peptides BPC-157, TB-500, and semax.2

With the criminal case thrusting peptide safety into the spotlight, we asked experts about the most significant risks consumers need to know about these injectables right now.

1. You Don’t Really Know What’s in the Vial

Labeling peptides as for “research use only” allows sellers to bypass regulation because the label indicates that the drugs are not intended for human use.

But without government oversight, there’s no guarantee the peptides actually contain what the seller claims. Paradigm Peptides, the company in the criminal case, advertised its products as American-made, 99% pure, and third-party tested—but prosecutors said that was all a lie.1

The drugs were illegally imported from China, India, and other countries, and were never quality tested.

Investigators even found that some of the unregulated drugs for sale, although not peptides, actually contained testosterone, a steroid hormone that can cause serious side effects when used without medical supervision.3

Customers who bought the peptides and other medications reported skin irritation, chronic acne, cardiac issues, stress, anxiety, and suicidal ideation.

And this wasn’t a small operation. From 2019 to 2024, Paradigm Peptides sold products to more than 54,000 customers in all 50 U.S. states and 80 countries worldwide, raking in a total of $5 million.1

“You run the risk of having a bait-and-switch,” C. Michael White, PharmD, a clinical pharmacologist and department head of pharmacy practice at the UConn School of Pharmacy, told HEALTH. “You also run the risk of being scammed out of your money.”

These quality problems are likely not unique to Paradigm Peptides. A 2026 study preprint (which hasn’t been peer-reviewed yet) analyzed more than 6,000 quality tests of 14 peptides—including BPC-157 and TB-500—and found that about 42% failed basic quality standards.4

Using stricter benchmarks for FDA-approved drugs, 71% failed. About 2.4% of samples did not contain the stated peptide at all.4

“You simply don’t know what you’re getting,” Priya Jaisinghani, MD, an endocrinologist and obesity medicine specialist at NYU Langone Health, told HEALTH. “These products may have problems with purity, potency, sterility, contamination, or dosing.”

2. Self-Injections Leave Room for Error

Unregulated peptides are typically taken as a shot—which comes with another set of risks, Jaisinghani said.

White and his colleagues recently studied how well people could self-administer unregulated peptides. They gave 20 adults a vial of semaglutide, an FDA-approved GLP-1 weight loss peptide, and asked them to demonstrate how to correctly dissolve the powder, draw it up into a syringe, and inject it into a mannequin.

In the real world, peptide sellers are not allowed to provide any instructions on using the medications. If they did, it would flag for the FDA that the peptides were not being sold for “research use only.” So the study participants did not receive any instructions, but they were given ample time to research on their own.

During the trial, people only completed an average of 44% of the steps correctly. Many participants didn’t use the correct dose, didn’t use the right amount of diluent, didn’t wash their hands beforehand, and used their fingers to recap needles—among other mistakes.5

“When you take all those things and you put them together, you could run the risk of overdose, underdosing, bleeding, infection, or skin irritation,” White said. “All of those things together could be real potential issues—outside of the problems of the manufacturing of the product.”

3. Compounding Doesn’t Eliminate Quality and Safety Risks

If the seven peptides under review by the FDA are eventually approved for compounding, their safety and quality would certainly improve, White said.

Compounding pharmacies are regulated by states and subject to FDA oversight, making their products far safer than gray-market peptides.

But they aren’t held to the same quality standards as FDA-approved drug manufacturers. Compounded medications are custom mixes and carry a greater risk of quality problems, such as contamination or containing too much or too little of the active ingredient.6

For instance, the FDA has documented issues with compounded GLP-1 medications, such as insufficient storage temperatures and dosing errors, which have been linked to more than 1,700 reports of adverse events.7

Allowing some peptides to be legally sold at compounding pharmacies may also not ensure they’re prescribed appropriately. Right now, anyone can buy peptides on the gray market without a prescription because they’re not technically meant for human use.

But compounded drugs can be fairly easy to access. A 2026 study found that online vendors often prescribed compounded versions of GLP-1s without requiring a patient to interact with a clinician.8

Without medical oversight, patients who are not good candidates for certain peptides may face additional health risks, White said.

4. The Effects in Humans Are Largely Unknown

Even if a peptide product is manufactured and administered correctly, the drug itself may still have unknown safety risks. That’s because none of the unregulated peptides have large, controlled human trials behind them, experts said.

The potential benefits are based on some promising animal and lab studies. “That is just the beginning of the drug development process,” White explained.

In the regular FDA approval process, the medication would then undergo multiple phases of human trials with increasing numbers of participants—a very rigorous system.

“Only about one in 10 really, really promising experimental drugs based on animal studies ever make it to be FDA-approved,” White said.9

The peptides on the gray market—including the seven being reviewed for compounding—have not undergone this process, leaving unanswered questions about their true effects in humans.

You might assume that peptides work based on the sheer number of people already taking them, but just because a friend or influencer recommends a product doesn’t mean it’s automatically safe and effective.

“There could be a lot of potential biases influencing how that person is feeling about that product,” White pointed out. “Some of them are conscious biases or conflicts of interest, and others may be subconscious.”

Ultimately, experts agreed that more high-quality research on peptides is needed to fully understand the balance between their potential benefits and risks.

“There’s not enough information about the products of high enough quality to really know what kind of risks you’re actually taking on,” White said. “I wish I could say that the only risk is that you’re most likely being scammed out of your money, but I don’t know that to be true.”