Is retatrutide safe?
Nobody can say yet. A phase 2 trial in 338 people reported a tolerability profile similar in kind to other incretin drugs with a heart-rate signal; phase 3 is what establishes safety and it is not finished.
Human trial data
Retatrutide Side Effects
Phase 2 human trial data exist; not approved anywhere — figures are from the phase 2 obesity trial
Retatrutide is unapproved and still in phase 3, so its safety profile is provisional. The phase 2 obesity trial reported dose-dependent gastrointestinal effects during escalation, discontinuations that rose with dose, and an increase in heart rate. Long-term safety is unknown.
Research-use information only. Research-grade Retatrutide is not an approved medicine; where trial or label figures appear below they belong to the pharmaceutical product studied, not to any research vial. This page does not give dosing or medical advice.
What is reported
Every rate carries its source. Where no source exists, no rate is printed.
| Effect | Rate (sourced) | Detail | Source |
|---|---|---|---|
| Gastrointestinal events (nausea, diarrhoea, vomiting, constipation) | not quantified | Dose-related, mostly mild-to-moderate, concentrated during escalation. | Jastreboff et al. 2023 (phase 2) |
| Discontinuation for adverse events | 6–16% across dose groups vs 0% placebo | Higher at higher doses. | Jastreboff et al. 2023 |
| Heart-rate increase | not quantified | Dose-dependent rise observed, greatest early in treatment. | Jastreboff et al. 2023 |
| Dysaesthesia / skin sensitivity | not quantified | Reported in the phase 2 programme at higher doses. | Jastreboff et al. 2023 |
What is not known
- •Everything beyond 48 weeks.
- •Cardiovascular outcomes (phase 3 ongoing).
- •Identity and dose of research-grade material — several vendors sell it under house codes without a CAS number.
Mechanism-based cautions
- •Assume GLP-1 class warnings apply until shown otherwise.
- •Glucagon-receptor activity adds a mechanism (hepatic glucose output, heart rate) the dual agonists do not have.
Regulatory status: Not approved anywhere; Eli Lilly phase 3 (TRIUMPH) ongoing as of 2026.
References
- Jastreboff AM, et al. Triple-hormone-receptor agonist retatrutide for obesity — a phase 2 trial. New England Journal of Medicine, 2023. PMID 37366315.
What is actually in a research vial
Everything above describes Retatrutide the molecule. The risk specific to a research vial is different: it may not contain Retatrutide at the labelled amount, and it may contain what the synthesis left behind. Identity (mass spectrometry), purity (HPLC), measured net content and an endotoxin result are the four lines on a certificate that bear on adverse effects, and only a certificate you can check at the laboratory tells you any of them. This is what we have verified for Retatrutide so far.
Who sells Retatrutide, and what they document
12 of the 77 vendors on our scoreboard list Retatrutide with a price we read on the product page (23 Aug 2026–2 Oct 2026). Of those, 11 name their testing laboratory, 10 publish certificates that resolve on the lab's own site, and 11 publish measured milligrams against the label. The full ranking, with every dated price, is on Best Retatrutide Vendors.
| Vendor | Rubric | Lab named | Price read |
|---|---|---|---|
| Peptide Giantspartner | 10/10 | Janoshik Analytical · Vanguard Laboratory | $65.99 · 10mg · 2 Oct 2026 |
| Purgo Labspartner | 10/10 | SteriGenix · Freedom Diagnostics | $59.99 · 10mg · 2 Oct 2026 |
| Amino Clubpartner | 9/10 | ILS Labs | $69.99 · 10mg · 2 Oct 2026 |
| Idun Peptides | 9/10 | Kovera Labs (named in certificate captions only) | $44.99 · 10mg · 5 Sept 2026 |
| Rivn Peptidespartner | 9/10 | Freedom Diagnostics | $99.99 · 10mg · 27 Aug 2026 |
Top 5 by rubric score; 7 more on the ranking page.
Retatrutide certificates we have opened
None yet for Retatrutide specifically. The COA library holds the certificates we have read for each vendor on other compounds, which is the next best signal of how that vendor documents a lot.