What are the side effects of Retatrutide?
The most commonly reported Retatrutide side effects are nausea (especially first 2 weeks of each titration step), constipation or diarrhea, fatigue / lethargy. Most are mild and tend to be dose dependent. It is generally avoided with history of medullary thyroid carcinoma or MEN-2. Human clinical evidence for Retatrutide is limited, so this reflects reported and observed effects, not a complete safety profile.
Reported Retatrutide side effects
- Nausea (especially first 2 weeks of each titration step)
- Constipation or diarrhea
- Fatigue / lethargy
- Reduced HRV in some users
- Underrating protein intake from low appetite
Who should avoid it
- History of medullary thyroid carcinoma or MEN-2
- Pancreatitis history
- Pregnancy / nursing
Bloodwork worth tracking
- Lipid panel
- Liver enzymes (ALT/AST baseline + every 3 mo)
- A1C if metabolic context
References
- Triple–Hormone-Receptor Agonist Retatrutide for Obesity (Phase 2) — Jastreboff AM et al., NEJM, 2023
- 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 conducted in the USA — Rosenstock et al., Lancet, 2023
- Triple hormone receptor agonist retatrutide for metabolic dysfunction-associated steatotic liver disease: a randomized phase 2a trial — Sanyal et al., Nature Medicine, 2024
Pepdex is an editorial reference, not medical advice. Peptides vary in legal and approval status by country, many are research compounds without full human safety data. Talk to a qualified clinician before starting anything.
More on Retatrutide
Last updated 2026-06-06.