What is Retatrutide?
Retatrutide (LY3437943) is Eli Lilly's triple GLP-1/GIP/glucagon receptor agonist in Phase III clinical trials. The TRIUMPH-4 trial (December 2025) achieved 28.7% average weight loss (71.2 lbs from a 248.5 lb baseline) at 68 weeks with 12mg — the highest weight loss efficacy recorded for any obesity medication to date. It is not FDA-approved. FDA has stated it cannot be lawfully compounded under 503A/503B.
Mechanism of Action
Triple receptor co-agonism: GLP-1R for appetite suppression and incretin effect, GIPR for improved insulin sensitivity, glucagon receptor for increased energy expenditure and hepatic fat oxidation — addressing obesity through three distinct metabolic pathways simultaneously
Target: GLP-1 receptor (GLP1R), GIP receptor (GIPR), Glucagon receptor (GCGR)
Research / educational reference. Educational research index only — not medical advice. Literature maturity is not a verdict on whether a compound works in people. Community reports are not evidence of efficacy.
Evidence at a glance
Derived · maturity-1.0Human efficacy is unproven unless an approved label or completed published efficacy program says otherwise. Counts reflect indexed literature volume/kind — never a verdict on effect.
Literature maturity
moderate 58/100
PubMed hits
178
CT.gov trials
34
Strong-human apps
0
Sample papers
8
Sample articles by era
- 2021-20232
- 2024-20268
Application grades (curated)
- Human-grade apps2
- Animal / in-vitro0
- Mechanistic0
Does literature support studied applications?
Grades reflect cited literature posture — not a treatment recommendation. Community notes are never efficacy evidence.
| Application | Cited evidence | Grade | Community |
|---|---|---|---|
| Obesity / overweight weight reduction (investigational) | Phase 2 published data show large mean weight reductions; phase 3 programs ongoing. | Limited human | Community reports vary; not evidence of efficacy. |
| Type 2 diabetes (investigational) | Early clinical programs evaluate glycemic endpoints alongside weight. | Limited human | Community reports vary; not evidence of efficacy. |
Pharmacology
Mechanism of action
- •Triple receptor co-agonism: GLP-1R for appetite suppression and incretin effect, GIPR for improved insulin sensitivity, glucagon receptor for increased energy expenditure and hepatic fat oxidation — addressing obesity through three distinct metabolic pathways simultaneously
- •Primary target framing: GLP-1 receptor (GLP1R), GIP receptor (GIPR), Glucagon receptor (GCGR)
Half-life
~6 days
Identity & chemistry
- CAS
- 2381089-83-2
- PubChem
- CID 171934787
- Formula
- C221H342N46O68
- Molar mass
- 4731 Da
- InChIKey
- MLOLQJNKXBNWFW-JMUPIODPSA-N
Identity cross-checked with PubChem where available. Compass HTML used only as a bootstrap checklist — not republished as product copy.
Storage & stability
- Lyophilized
- 2–8°C; lyophilized typical shelf 12–24 months
- Reconstituted
- 2–8°C; in-use window often 21–30 days (product-dependent)
- Tell-tale degradation
- !Cloudiness, clumping, or particles after mixing
- !Discoloration versus the expected clear/colorless (or labeled) solution
- !Failed or incomplete reconstitution of lyophilized cake
Educational estimates. Prefer product labeling and peptide shelf-life tool.
Lab handling posture
Research / educational handling notes only. Not a substitute for an SDS.
- •Use PPE appropriate for peptide powder/solution handling
- •Avoid inhalation of lyophilized powder; handle spills per institutional policy
- •Do not present research materials as medicines
Sample indexed literature
- Triple-Hormone-Receptor Agonist Retatrutide for Obesity - A Phase 2 Trial.
The New England journal of medicine · 2023 · PMID 37366315
- Effects of retatrutide on body composition in people with type 2 diabetes: a substudy of a phase 2, double-blind, parallel-group, placebo-controlled, randomised trial.
The lancet. Diabetes & endocrinology · 2025 · PMID 40609566
- Retatrutide-A Game Changer in Obesity Pharmacotherapy.
Biomolecules · 2025 · PMID 40563436
- Retatrutide for the treatment of obesity, obstructive sleep apnea and knee osteoarthritis: Rationale and design of the TRIUMPH registrational clinical trials.
Diabetes, obesity & metabolism · 2026 · PMID 41090431
- 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.
Lancet (London, England) · 2023 · PMID 37385280
- Triple hormone receptor agonist retatrutide for metabolic dysfunction-associated steatotic liver disease: a randomized phase 2a trial.
Nature medicine · 2024 · PMID 38858523
Research Indications
Clinical trials demonstrate significant body weight reduction with sustained benefit
Improves glycemic control and A1C levels in type 2 diabetes
Associated with reduced cardiovascular events in high-risk patients
Addresses multiple components of metabolic syndrome simultaneously
Research Protocols
These are commonly discussed research protocols — not medical advice. Consult a healthcare provider before use.
| Goal | Dose | Frequency | Route |
|---|---|---|---|
| Published trial range (early titration) | 0.5–1 mg | Once weekly | Subcutaneous injection |
| Published trial range (low) | 2 mg | Once weekly | Subcutaneous injection |
| Published trial range (mid) | 4 mg | Once weekly | Subcutaneous injection |
| Published trial range (higher) | 8 mg | Once weekly | Subcutaneous injection |
| Published trial range (highest studied) | 12 mg | Once weekly | Subcutaneous injection |
Peptide & Drug Interactions
Always consult your healthcare provider before combining with other compounds. Use our Interaction Checker for reference.
How to Reconstitute & Inject
Use bacteriostatic (BAC) water only. Avoid saline — may cause precipitation. Refrigerate and use within 28 days.
- 1
Remove Retatrutide vial from refrigeration and allow to reach room temperature (15–20 minutes)
- 2
Clean vial top with alcohol swab and allow to air dry completely
- 3
Using a sterile syringe, draw the calculated volume of bacteriostatic water (BAC water)
- 4
Inject BAC water slowly down the side of the vial — do not aim directly at the powder
- 5
Gently swirl in circular motions — DO NOT shake vigorously as this degrades the peptide
- 6
Allow 2–3 minutes for full dissolution — solution should be clear and colorless
- 7
Draw calculated dose into an insulin syringe for subcutaneous injection
- 8
Inject into abdomen, thigh, or upper arm. Rotate injection sites to prevent lipodystrophy
- 9
Store reconstituted solution refrigerated (2–8°C) and use within 28 days
What to Expect
Week 1–2
Initial appetite suppression may begin. Mild GI effects (nausea, fullness) as your body adapts.
Week 2–4
Noticeable reduction in food cravings and portion sizes. Early weight changes begin.
Week 4–8
Significant appetite control and steady weight loss. Improved blood sugar if applicable.
Week 8–16
Substantial weight reduction and enhanced energy. Metabolic markers begin improving.
Week 16–24
Major weight loss milestone with cardiovascular benefits and improved lipid profiles.
Week 24+
Maximum clinical efficacy. Comprehensive metabolic improvements and sustained benefits.
Side Effects & Safety
- Nausea (most common, typically dose-dependent and transient)
- Diarrhea or constipation during dose escalation
- Vomiting, especially when starting or increasing dose
- Reduced appetite and early satiety
- Injection site reactions (redness, bruising)
- Fatigue, particularly in early weeks
- Rare: Pancreatitis — discontinue immediately with severe abdominal pain
- Rare: Thyroid C-cell effects (contraindicated with MEN2 or thyroid cancer history)
Retatrutide is investigational and not FDA-approved. FDA has stated it cannot be lawfully compounded under 503A/503B. PeptIQ does not sell peptides or list vendors. Talk with a licensed clinician.
FDA Status & Regulatory Info
Retatrutide (LY3437943) is Eli Lilly's triple GLP-1/GIP/glucagon receptor agonist in Phase III clinical trials. The TRIUMPH-4 trial (December 2025) achieved 28.7% average weight loss (71.2 lbs from a 248.5 lb baseline) at 68 weeks with 12mg — the highest weight loss efficacy recorded for any obesity medication to date. It is not FDA-approved. FDA has stated it cannot be lawfully compounded under 503A/503B.
Frequently Asked Questions
Research References
External links for education only. We do not control third-party content.
Community-reported data
The information below reflects self-reported experiences from PeptIQ app users. It is not clinical evidence and should not replace professional medical advice.
Community Intelligence
What 125 users report
Overall experience
From check-in ratings — separate from side effects logged below. Side effects are logged separately from overall experience. A favorable check-in can still include nausea, fatigue, or injection-site reactions.
Favorable 99% · Mixed 1% · Unfavorable overall 0%
Most reported benefits
Benefits users selected when logging a favorable or mixed check-in.
Most logged side effects
Side effects are logged separately from overall experience. A favorable check-in can still include nausea, fatigue, or injection-site reactions.
Self-reported dose per injection
Median bucket: 2–3 mg · Most common: 1–2 mg
Reports span 0 to ≥ 5 mg (open-ended top bucket)
Anonymized self-reports from PeptIQ users — not prescribing guidance. Buckets group similar logged amounts; open-ended top buckets mean “at least” that dose.
Commonly stacked with
How repeat users are trending
Among repeat reporters, 100% said they felt similar to their last entry, 0% more positive, and 0% more negative.
Overall, repeat reporters leaned similar or mixed compared to their previous entry.
Median gap between entries: 51 days · Based on 45 repeat reporters
Share Your Experience
Rate Retatrutide in the PeptIQ app and help the community make informed decisions.
Educational information only
This page is for educational reference. It is not medical or legal advice. PeptIQ does not sell peptides or list vendors. Consult the FDA and a licensed healthcare professional for current regulations and individualized guidance.