What is Retatrutide?
Retatrutide: Once-weekly injectable triple agonist of GIP, GLP-1 and glucagon receptors (Eli Lilly, LY3437943). The sources cited here most often discuss it for: Large weight loss; Blood sugar control; Less liver fat. Evidence label: Trial-backed.
- Type
- Peptide
- Family
- Weight & Metabolic
- Evidence label
- Trial-backed (4 of 5)
- Regulatory status
- Not a component of any FDA-approved drug; FDA states retatrutide cannot be used in compounding under federal law and has not been found safe and effective for any condition, and has warned companies marketing or selling unapproved versions.
- Goals discussed
- Fat Loss & Metabolism, Heart, Liver & Kidney
- Also called
- LY3437943, reta, triple G, trillion-dollar drug, Reta
- Last reviewed
- 2026-10-11
- Once-weekly injectable triple agonist of GIP, GLP-1 and glucagon receptors (Eli Lilly, LY3437943); investigational, NOT FDA-approved as of Oct 2026 (phase 3 TRIUMPH/TRANSCEND trials reporting); widely sold grey-market.12
Regulatory status Not a component of any FDA-approved drug; FDA states retatrutide cannot be used in compounding under federal law and has not been found safe and effective for any condition, and has warned companies marketing or selling unapproved versions. 3
Names as used in gyms, forums and gray-market listings. Reported, not endorsed; stacks have not been studied as combinations.
In adults with obesity, retatrutide resulted in significant weight reduction, reduced pain in participants with knee osteoarthritis, and reduced apnea-hypopnea events in participants with obstructive sleep apnea.
Conclusion of the 80-week phase 3 TRIUMPH-1 trial in 2339 adults with obesity (N Engl J Med, 2026; Lilly-funded).
What is Retatrutide researched for?
The three outcomes most discussed for Retatrutide in the sources below, as those sources report them. humanpeptides.fyi makes no claims of its own: a listed benefit can be unproven or can have failed in trials, and the label on each line says which.
Less liver fat
- Liver fat reduced ~82-86% (12 mg) in MASLDphase 2a RCT
- Knee osteoarthritis pain (WOMAC) improved with 26-29% weight loss in TRIUMPH-4 (phase 3, company-reported)
What do researchers and users say about Retatrutide?
Patients have reported serious harms after taking black-market retatrutide they purchased online, including hospitalizations.
The drug's developer commenting on unapproved retatrutide sold online, August 2026.
My RHR went up by 10 for the first 2 months on reta and now has been in a steady decline the past 2 months.
Unverified self-report on resting heart rate; others in the thread stopped because of persistent heart-rate rises.
What side effects of Retatrutide are reported?
- GI effects (nausea, vomiting, diarrhea, constipation) most common, dose-dependent (phase 2/3)1
- Dysesthesia (skin sensitivity) 2-4.5% vs 0% placebo (phase 3 T2D)6
- Elevated resting heart rate/palpitations reported by usersanecdotal Reddit1312
- In the TRIUMPH-4 knee osteoarthritis trial, 12% to 18% stopped treatment due to adverse events on the higher doses vs 4% on placebo, including discontinuations for perceived excessive weight loss.phase 3 topline (manufacturer)8
- Gray-market users had a higher burden of new cardiovascular and neuropsychiatric symptoms than matched semaglutide or tirzepatide users.observational preprint11
- Gray-market products are sometimes co-formulated with other unapproved peptides (such as cagrilintide or BPC-157), and their content, purity and strength cannot be verified.observational study and clinician comment11
What do peptide guides say about Retatrutide?
- Dr. Axe Dr. Axe lists retatrutide as research only, with human studies, describing it as an investigational GIP, GLP-1 and glucagon receptor agonist. 14
- PepEdHub PepEdHub explains the triple action: GLP-1 and GIP curb appetite while glucagon raises energy expenditure and fat burning, and lists obesity, type 2 diabetes and fatty liver disease as research targets. 15
- PubMed In phase 3 TRIUMPH-1, retatrutide produced significant weight loss and also reduced knee osteoarthritis pain and sleep apnea events in those subgroups. 10
- CNBC Lilly says it will seek approval in the first quarter of 2027, delaying from 2026 because it needs more time to gather manufacturing and quality-control data for regulators. 16
- Medscape An observational study of health records found gray-market retatrutide users lost about half the weight seen in trial participants while still showing the drug's typical heart-rate rise. 11
What does the research say, system by system?
How strong is the evidence for Retatrutide?
Strong human phase 2 and phase 3 RCT data; not yet FDA-approved; grey-market use risky
Larger randomized human trials exist, positive or negative, but no US approval for the uses discussed. How tiers work
Questions about Retatrutide
What is Retatrutide?
Once-weekly injectable triple agonist of GIP, GLP-1 and glucagon receptors (Eli Lilly, LY3437943).
Is Retatrutide FDA-approved?
Not a component of any FDA-approved drug; FDA states retatrutide cannot be used in compounding under federal law and has not been found safe and effective for any condition, and has warned companies marketing or selling unapproved versions.
What is Retatrutide researched for?
The sources cited on this page most often discuss three outcomes: Large weight loss; Blood sugar control; Less liver fat. Each line above shows what the source reports and how strong that evidence is.
What side effects of Retatrutide are reported?
Reported in the cited sources: GI effects (nausea, vomiting, diarrhea, constipation) most common, dose-dependent (phase 2/3); Dysesthesia (skin sensitivity) 2-4.5% vs 0% placebo (phase 3 T2D); Elevated resting heart rate/palpitations reported by users. The list is not complete, and few listed risks does not mean a compound is safe.
How strong is the evidence for Retatrutide?
Evidence label: Trial-backed. Strong human phase 2 and phase 3 RCT data; not yet FDA-approved; grey-market use risky.
What else is Retatrutide called?
Names used for it include LY3437943, reta, triple G, trillion-dollar drug, Reta.
Does humanpeptides.fyi recommend Retatrutide?
No. humanpeptides.fyi makes no claims and no recommendations of its own. It summarizes and links to what others have published and posted. Nothing here is medical advice; talk to a licensed clinician.