Peptide side effects: what the research says
Real clinical trial data, adverse event rates, and safety warnings. No hype, no dismissed risks.
| Peptide | Evidence level | Primary adverse events & safety profile | |
|---|---|---|---|
| BPC-157 Healing peptide | Animal studies only | No serious adverse events have been reported in the few human reports, but those reports cover under 20 people in total and cannot rule out risk. Reviewers note... | View safety data → |
| TB-500 Healing peptide | Animal studies only | Human safety data for TB-500 is lacking. Theoretical concerns include effects on cell migration and blood vessel growth in people with cancer; Tβ4 expression is... | View safety data → |
| GHK-Cu Skin & tissue peptide | Animal studies only | Topical use is generally considered low risk; skin irritation is the usual concern. For injectable GHK-Cu there is no human safety data. Copper is an essential ... | View safety data → |
| Semaglutide GLP-1 receptor agonist | FDA-approved | Gastrointestinal effects (nausea, vomiting, diarrhea, constipation) are the most common and mostly occur during dose escalation. Weight is typically regained af... | View safety data → |
| Tirzepatide GIP/GLP-1 receptor agonist | FDA-approved | Gastrointestinal events were most common and mostly mild to moderate, mainly during dose escalation. In SURMOUNT-1, treatment discontinuation due to adverse eve... | View safety data → |
| CJC-1295 Growth hormone-releasing peptide | Human trials | Short trials reported no serious adverse reactions, but they involved few people over weeks. Raising GH and IGF-1 long term raises theoretical concerns (fluid r... | View safety data → |
| Ipamorelin Growth hormone secretagogue | Human trials | In the ileus trial adverse events were common in both groups (87.5% ipamorelin vs 94.8% placebo), largely reflecting surgery. Long-term safety of repeated use f... | View safety data → |
| Retatrutide Weight loss peptide | Human trials | Adverse events in clinical trials are predominantly gastrointestinal: nausea (affecting up to 45% on the highest dose), diarrhea, vomiting, and constipation. Th... | View safety data → |
| PT-141 Sexual health peptide | FDA-approved | The most frequent side effect in clinical trials is nausea, occurring in roughly 40% of patients (and leading to discontinuation in about 8%). Nausea typically ... | View safety data → |
| Tesamorelin Growth hormone secretagogue | FDA-approved | Adverse events in clinical trials include injection site reactions (erythema, pruritus, or pain in ~17%), arthralgias (13%), peripheral edema (6%), and myalgias... | View safety data → |