What are the side effects of retatrutide?

In clinical trials, the most commonly reported side effects of retatrutide were gastrointestinal — nausea, vomiting, diarrhea, and constipation — similar to other GLP-1-based medications and often related to how quickly the dose is increased. Because retatrutide is investigational and not FDA-approved, its complete safety profile is still being studied, and there is no approved dosing to guide safe use outside a trial.

What trials have reported

GI symptoms were the most frequent and were generally described as mild to moderate and more common during dose escalation. As with other medications in this class, slower titration tends to reduce these effects. Heart-rate changes and other effects have also been evaluated in studies.

An important caution

Side-effect data from a controlled trial does not tell you what will happen with an unregulated peptide of unknown purity and dose. Without physician supervision, you can't safely manage side effects or catch warning signs. This is a major reason self-sourcing retatrutide is unsafe — approved GLP-1 options come with proper monitoring.

Medically reviewed by Dr. Michael Mimlitz, MD (NPI 1508891870), Chief Physician of GOAL.MD. Physician-supervised telehealth. More at goal.md/answers.