Retatrutide Side Effects and Safety
Reported Retatrutide side effects, contraindications, and safety signals.
Cardiovascular Risk Factor Improvement
Clinical trials demonstrate comprehensive improvements in cardiometabolic risk factors including significant blood pressure reductions, improved lipid profiles with decreased triglycerides and increased HDL cholesterol, and reduced inflammatory markers. Research shows reductions in waist circumference and visceral adipose tissue that correlate with metabolic improvements. Studies document improvements in insulin sensitivity and metabolic syndrome components. The glucagon receptor activation may provide unique benefits for cardiac function through direct effects on the heart. Cardiovascular outcomes trials are planned to evaluate effects on hard clinical endpoints.
Safety & Tolerability
Retatrutide is an investigational triple agonist with substantial human Phase 1b/2 safety data. In its Phase 2 trials, the most common adverse events were gastrointestinal — nausea, diarrhea, vomiting, and constipation — described as mild-to-moderate and dose-related, and partially mitigated by a lower starting dose. The adverse-event profile was characterized as consistent with GLP-1 and GIP/GLP-1 receptor agonists. Retatrutide is not approved for any use. Human data: Human evidence is comparatively extensive for an investigational peptide: completed first-in-human Phase 1b and Phase 2 trials in type 2 diabetes, obesity, and MASLD, with a Phase 3 program (TRIUMPH) ongoing. Long-term safety and cardiovascular outcomes are not yet established — no completed cardiovascular outcomes trial exists as of 2026 — and dose-dependent increases in heart rate were observed in Phase 2, a class effect under continued study. Regulatory status: Not approved by the FDA or any regulatory agency; investigational, in Phase 3 development. In the Phase 2 obesity trial, the most common adverse events were gastrointestinal and dose-related, mostly mild-to-moderate, and were partially mitigated by a lower (2 mg vs 4 mg) starting dose; dose-dependent heart-rate increases were observed, peaking around 24 weeks. Human trial In the Phase 2 obesity trial, the most common adverse events were gastrointestinal and dose-related, mostly mild-to-moderate, and were partially mitigated by a lower (2 mg vs 4 mg) starting dose; dose-dependent heart-rate increases were observed, peaking around 24 weeks. In the Phase 2 type 2 diabetes trial, the most common adverse events were gastrointestinal (nausea, diarrhoea, vomiting, constipation), mild-to-moderate and dose-dependent (roughly 13% at the lowest dose to 50% at a higher dose); no severe hypoglycaemia and no deaths were reported. Human trial In the Phase 2 type 2 diabetes trial, the most common adverse events were gastrointestinal (nausea, diarrhoea, vomiting, constipation), mild-to-moderate and dose-dependent (roughly 13% at the lowest dose to 50% at a higher dose); no severe hypoglycaemia and no deaths were reported. First-in-human Phase 1b multiple-ascending-dose research characterized retatrutide's initial safety and tolerability and informed the gradual dose-escalation schedule used in later trials.
Contraindications
- personal/family history of medullary thyroid carcinoma
- MEN 2
- pancreatitis
- pregnancy
References
- Triple–Hormone–Receptor Agonist Retatrutide for Obesity — A Phase 2 Trial · Jastreboff AM, et al. · 2023
- Jastreboff AM, et al. Triple–Hormone-Receptor Agonist Retatrutide for Obesity, A Phase 2 Trial. N Engl J Med. 2023;389:514-526. · Jastreboff AM, Kaplan LM, Frías JP, Wu Q, Du Y, Gurbuz S, Coskun T, Haupt A, Milicevic Z, Hartman ML · 2023
- Retatrutide for the treatment of obesity, obstructive sleep apnea and knee osteoarthritis: Rationale and design of the TRIUMPH registrational clinical trials. · Giblin K, Kaplan LM, Somers VK et al. · 2026
- Appetite, eating attitudes, and eating behaviours during treatment with retatrutide in adults with type 2 diabetes: Results of a phase 2 study · Kanu C, Boye KS, Poon JL, Goetz I, Williamson S, Lou J, Hartman ML, Martin CK, Coskun T · 2025
- Rosenstock J, et al. Retatrutide, a GIP, GLP-1 and glucagon receptor agonist, for people with type 2 diabetes: a randomised, double-blind, placebo and active-controlled, parallel-group, phase 2 trial. Lancet. 2023;402(10401):529-544. · Rosenstock J, Frias J, Jastreboff AM, Du Y, Lou J, Gurbuz S, Thomas MK, Hartman ML, Haupt A, Milicevic Z, Coskun T · 2023
- Effects of retatrutide on body composition in people with type 2 diabetes. Lancet Diabetes Endocrinol. 2025. · 2025