What is peptide therapy? What to know before your first consultation

What are peptides?

Peptides are short chains of amino acids, the same building blocks that make up proteins. Many of the body's most important signaling molecules are peptides: insulin, glucagon and GLP-1 (glucagon-like peptide-1) are all peptide hormones that tell cells what to do. Because they act as messengers, peptides have become a rich area for drug development, and the NIH's National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) traces the modern weight-management medications to exactly this kind of basic research on one pancreatic hormone: GLP-1.

"Peptide therapy" in the wellness world usually means giving a peptide by injection, tablet or other route to influence a specific system: appetite and metabolism, growth hormone signaling, recovery, or aging. The problem is that the term covers everything from rigorously studied, FDA-approved medicines to compounds that have never been tested in humans.

Which peptides are FDA-approved?

A number of peptide-based drugs are FDA-approved and well studied. GLP-1 receptor agonists such as semaglutide, and the dual GIP/GLP-1 agonist tirzepatide, are approved for type 2 diabetes and, in certain formulations, for weight management when used together with diet and physical activity. NIDDK describes these as FDA-approved weight-management medications and notes that at diabetes doses, GLP-1 receptor agonists lower blood glucose and can reduce weight by roughly 3 to 5 percent: Prescription Medications to Treat Overweight and Obesity.

By contrast, many of the peptides marketed as "anti-aging," "recovery" or "longevity" therapies, such as BPC-157, have never been submitted to the FDA for approval and have little or no human clinical evidence. FDA approval matters: it means a product has been reviewed for safety, quality and effectiveness for a specific use, at a specific dose.

What about compounded peptide products?

Compounding is when a pharmacy prepares a medication that is not commercially available. When FDA-approved GLP-1 drugs were in shortage, compounding of copycat versions became common. That legal basis has been narrowing: tirzepatide left the FDA's drug shortage list in December 2024 and semaglutide in February 2025, and in April 2026 the FDA proposed excluding semaglutide, tirzepatide and liraglutide from the list of bulk substances outsourcers may compound, while clarifying that its enforcement discretion for compounding GLP-1s has ended: FDA statement on GLP-1 compounding policies.

The FDA has also flagged real risks in this space. Its review of adverse event reports found more than 455 reports involving compounded semaglutide and more than 320 involving compounded tirzepatide, including dosing errors with multidose vials, counterfeit products carrying false labels, and unapproved salt forms of the drugs. The agency's concerns with unapproved GLP-1 drugs page is worth reading before buying anything online.

Other popular peptides have their own regulatory stories. BPC-157 is not FDA-approved, and the FDA has grouped it with substances flagged for safety concerns; an advisory committee vote in 2026 recommending it for compounding does not make it approved or demonstrate clinical effectiveness. Sermorelin, a growth-hormone-releasing hormone analog, remains legally compoundable, but the only FDA-approved sermorelin product was discontinued years ago, so compounded versions are not the same as a product that went through FDA review.

What does the evidence show?

The evidence is uneven across the category. For weight management, the strongest and most credible data supports the FDA-approved GLP-1 medications, which NIDDK describes as working best alongside diet and physical activity. It also notes that when people stop these medications, significant weight regain is common, so they are a tool in a longer-term plan, not a one-way fix.

For most wellness peptides, the human evidence is thin. Compounds like BPC-157 have been studied mostly in animal models, and findings from animal research do not automatically translate to people. A responsible provider will tell you where the evidence stands for the specific peptide you are asking about, and will not present an experimental product as established care.

What are the risks and limitations?

Risks depend entirely on the product. FDA-approved GLP-1 medications have studied side effect profiles, most commonly gastrointestinal effects, and are prescribed under medical supervision with clear follow-up. Unapproved and compounded peptides carry more unknowns: uncertain dosing, contamination or quality issues in some compounded products, injection-site reactions, and long-term effects that simply have not been studied. Peptides can also interact with existing conditions and medications, so individual evaluation matters. Anyone promising specific results from an unapproved peptide is overstating what is known.