A University of Missouri physician is warning consumers about the potential dangers of injecting peptides that have not been approved by the Food and Drug Administration.
Peptides are substances produced naturally by the body that help control functions such as blood sugar, appetite and growth. They can also be manufactured for use in medications, including popular diabetes and weight-loss drugs such as Ozempic and Wegovy.
But some companies also sell peptides that have not been approved by federal regulators, promoting them for everything from muscle recovery to anti-aging.
The warning comes as a Washington University survey finds that St. Louisans are becoming more familiar with weight-loss drugs, although Black residents are less likely than White residents to believe they work.
Peptide products are increasingly advertised on social media, cable television and podcasts, with claims that they can help with everything from improving skin appearance to relieving muscle soreness.
“I think any time you’re getting something from someone who financially benefits from your purchase in medicine, you should be concerned about your purchase and look into it really thoroughly,” said Dr. Regina DePietro, an MU Health Care community and family medicine physician.
The FDA has approved some peptide-based medications, including Ozempic, for specific medical uses. But other products, such as BPC-157, have not undergone the same review to determine whether they are safe and effective.
Unlike approved medications, unapproved peptides may be sold without adequate testing, leaving consumers uncertain about their ingredients, effectiveness and potential side effects.
A July survey by Washington University’s iHeard STL project found that 59% of Black St. Louis respondents believed GLP-1 weight-loss drugs were effective, compared with 75% of White respondents.
Two years earlier, the figures were nearly identical — 47% among Black respondents and 45% among White respondents. Confidence increased among both groups, but much more sharply among White respondents.
Overall, 91% of respondents in July had heard of the medications, but only 30% believed they were safe.
The surveys included 156 St. Louis adults in March 2024 and 179 in July 2026.
Residents raised questions about long-term side effects, whether weight loss could be maintained, insurance coverage and cost. One respondent asked, “How safe are the ones people order online?”
The survey measured perceptions of GLP-1 weight-loss drugs, not the use of unapproved peptides. It does not establish whether Black St. Louisans are more likely to purchase the unapproved products.
Online retailers and some compounding pharmacies offer peptide products that have not undergone FDA approval. Some are labeled “for research purposes,” even as they are marketed to consumers interested in weight loss, muscle recovery or other health benefits.
“When you have unregulated medication, we don’t have that post-market surveillance making sure that our medications are safe and are actually what they say they are,” DePietro said.
“Does that mean that these will never be safe and studied? No. These might become medications that are approved eventually. I just think we don’t have the research yet.”
Health experts warn that unapproved peptides may cause immune reactions, contain contaminants or produce unintended side effects. Some products may be ineffective or fraudulently marketed.
Some pharmacies also prepare customized versions of medications for individual patients. These compounded drugs are not FDA approved, although they can be legally made under certain conditions. They are different from experimental peptides marketed online.
DePietro recommends that anyone considering a peptide product consult a physician first.
St. Louis American staff contributed to this report.