Reviewed & approved by Dr. Nova Reyes · Last checked 2026-10-25. ← Back to Evidence Library
Efinopegdutide: what the evidence says
At a glance
What it is: an experimental long-acting injected peptide that activates two receptors, GLP-1 (the target of semaglutide) and glucagon. It was first developed by Hanmi, tested by Johnson & Johnson under the code JNJ-64565111, and is now developed by Merck as MK-6024. R1, R2, R3
What the evidence says: in one open-label phase 2 trial in fatty liver disease, it cut liver fat more than semaglutide. In two older phase 2 trials, it caused weight loss vs placebo (a dummy treatment), but in people with type 2 diabetes blood sugar did not improve. R1, R2, R3
Biggest risks: nausea and vomiting were more common than with placebo, liraglutide or semaglutide. Many people stopped early in the older trials. Long-term safety is unknown. Gray-market vials add unknown identity, strength and purity. R1, R2, R3
| Human Human evidence (fatty liver, liver fat) | Limited: one open-label phase 2a RCT (randomized controlled trial; 145 people) vs semaglutide, measuring liver fat on scans, not liver scarring; a larger phase 2b trial finished without published results R1, R4 |
| Human Human evidence (weight) | Limited: two phase 2 RCTs (474 and 195 people) vs placebo, plus weight data from the liver trial; high dropout; no phase 3 R1, R2, R3 |
| Human Human evidence (type 2 diabetes, blood sugar) | Very limited (mixed results): one short phase 2 RCT produced weight loss but found no HbA1c improvement and a slight rise in fasting glucose and fasting insulin R3 |
| Animal Animal evidence | Not rated here |
| Regulatory | Not FDA-approved (no Drugs@FDA record) · EU, Japan, China: UNVERIFIED not checked against EMA, PMDA or NMPA · WADA: not named; S0 (unapproved substances) likely applies R5 |
| Established human dose | None. There is no label. Trial study arms are listed only in Study details |
Evidence verdict: Human (liver fat): Limited · Human (weight): Limited · Human (type 2 diabetes): Very limited (mixed results) · Animal: not rated here Card verdict: Limited (liver fat and weight) · Type 2 diabetes: Very limited (mixed results) Card note: Varies by use, see page
This page reports what studies used. It is not dosing advice.
Legend: HUMAN data · ANIMAL / LAB data · UNKNOWN · UNVERIFIED: not yet confirmed against a primary source
What is it?
Efinopegdutide is a lab-made peptide that activates both the GLP-1 receptor and the glucagon receptor. R1 GLP-1 action lowers appetite. Glucagon action raises energy use and may push the liver to burn fat directly, which is why it is being studied for fatty liver disease. R1 Glucagon also raises blood sugar, which may explain the diabetes result below. R3 Unknown
Does it help fatty liver disease?
- Human Phase 2a vs semaglutide: in 145 adults with fatty liver (a third had type 2 diabetes), liver fat on MRI fell by 72.7% on efinopegdutide vs 42.3% on semaglutide. R1
- Caution The trial was open-label (everyone knew which drug they got), short, and funded by Merck. It measured liver fat, not liver inflammation or scarring, which are what matter most for long-term health. R1
- Unknown A larger phase 2b trial in MASH, which looks at liver biopsies, was completed in late 2025, but we found no posted or published results. R4
Does it help weight loss?
- Human J&J phase 2, obesity without diabetes: 474 adults with severe obesity. Weight loss beyond placebo was 6.8% to 10.0% across groups, vs 5.8% beyond placebo for liraglutide. Only 72.4% completed treatment. R2
- Human J&J phase 2, obesity with type 2 diabetes: 195 adults; weight loss beyond placebo was 4.6% to 7.2% over a short trial. R3
- Human Liver trial: weight fell 8.5% vs 7.1% on semaglutide, a difference that was not statistically clear. R1
Does it help type 2 diabetes?
- Human No. In the J&J diabetes trial, HbA1c (average blood sugar) did not change, and fasting glucose and insulin rose slightly. R3 This is the opposite of what GLP-1 drugs usually do.
Is it safe?
What the trials reported:
- Caution Nausea and vomiting were more common than with placebo and liraglutide, and stomach side effects were more common than with semaglutide. R1, R2, R3
- Caution Blood sugar: may rise in people with diabetes. R3
- Caution Dropouts: about a quarter of people did not complete treatment in the J&J trials. R2, R3
- Caution GLP-1 class risks: Efinopegdutide acts on the GLP-1 receptor, so the risks known for that drug class (pancreatitis, gallbladder disease, rodent thyroid tumors, low blood sugar with insulin or sulfonylureas, older blood-sugar-lowering pills) are reasonable to expect; see the semaglutide page. Unknown The abstracts we reviewed do not report rates of these events.
- Unknown Heart safety and long-term safety are unknown.
Compounded and gray-market Efinopegdutide: extra risks
- Caution Unregulated "research" vials. Because efinopegdutide is only used inside clinical trials, any vial sold online has no regulatory quality control, and its identity, strength and sterility are unknown.
- Caution Don't stack with other GLP-1 drugs. Taking Efinopegdutide with semaglutide, tirzepatide, retatrutide or similar drugs means two drugs acting on the same receptor, which no trial on this page tested. Unknown
- Caution Measuring mistakes. FDA has reported people hospitalized after drawing up too much from multi-injection GLP-1 vials. The same syringe-marking problem applies here. See the section on measuring mistakes on our semaglutide page.
What we don't know
- Unknown What is actually in a given gray-market vial
- Unknown Whether it improves liver inflammation or scarring R4
- Unknown Results of the phase 2b MASH trial R4
- Unknown Whether Merck will start phase 3
- Unknown Long-term safety
Is it legal?
Not FDA-approved; no Drugs@FDA record was found (openFDA search, Oct 24, 2026). We found no registered phase 3 trial and no announced filing for approval. R4 EU, Japan, China: UNVERIFIED not checked against EMA, PMDA or NMPA. WADA: not named on the 2026 Prohibited List; S0 bans at all times any unapproved substance in development that no other section covers, which describes Efinopegdutide R5. WADA has not ruled on Efinopegdutide by name. As of Oct 24, 2026.
What's in the vial?
Real efinopegdutide is only available inside clinical trials. We have not found published lab tests of gray-market Efinopegdutide. Under the Open Peptide Standard, a GLP-1 vial overfilled by more than 20% is a critical fail (draft threshold). See results at /tests/. A passing test covers one batch, tested on one date. It does not mean the compound itself is safe.
What do users report?
Self-report, not evidence.
Unknown TBD. We'll only list this once we can cite a public source.
Study details
These are doses researchers used, not recommendations. All injections subcutaneous.
R1 Human: Fatty liver (Merck)
| Study | People | Route | Dose used | Follow-up | Reported | Side effects / dropouts | Citation |
|---|---|---|---|---|---|---|---|
| Phase 2a, open-label (Romero-Gómez 2023), NCT04944992 | 145 (72 vs 73) | Subcutaneous | Efinopegdutide 10 mg once weekly vs semaglutide 1 mg once weekly, titrated over 8 weeks | 24 wk | Liver fat −72.7% vs −42.3% (p<0.001); weight −8.5% vs −7.1% (p=0.085) | Slightly more AEs, mainly GI | PMID 37355043 |
R2, R3 Human: Weight and diabetes (Janssen, as JNJ-64565111)
| Study | People | Route | Dose used | Follow-up | Reported | Side effects / dropouts | Citation |
|---|---|---|---|---|---|---|---|
| Phase 2, obesity BMI 35–50, no T2D (Alba 2021) | 474 | Subcutaneous | 5.0, 7.4 or 10.0 mg, no escalation, vs placebo; open-label liraglutide 3.0 mg | 26 wk | Placebo-subtracted −6.8%, −8.1%, −10.0%; liraglutide −5.8% | More nausea and vomiting; 72.4% completed | PMID 33475255 |
| Phase 2, T2D with BMI 35–50 (Di Prospero 2021) | 195 | Subcutaneous | 5.0, 7.4 or 10.0 mg vs placebo | 12 wk | Placebo-subtracted −4.6%, −5.9%, −7.2%; no HbA1c change; fasting glucose rose (5.0, 7.4 mg) | More nausea and vomiting; 73.8% completed | PMID 33475251 |
R4 Ongoing trials (as of Oct 24, 2026)
ClinicalTrials.gov: phase 2b in MASH NCT05877547, 381 enrolled, completed Dec 2025, no results posted. No phase 3 found. FDA: no Drugs@FDA record (openFDA query, Oct 24, 2026). EMA, PMDA, NMPA: UNVERIFIED not checked.
Full reference list (all PMIDs verified on PubMed, Oct 24, 2026)
- Romero-Gómez M, et al. J Hepatol. 2023;79(4):888-897. doi:10.1016/j.jhep.2023.05.013. PMID 37355043
- Alba M, et al. Clin Obes. 2021;11(2):e12432. doi:10.1111/cob.12432. PMID 33475255
- Di Prospero NA, et al. Clin Obes. 2021;11(2):e12433. doi:10.1111/cob.12433. PMID 33475251
- ClinicalTrials.gov. NCT05877547.
- WADA. World Anti-Doping Code International Standard: Prohibited List 2026 (in force Jan 1, 2026). https://www.wada-ama.org/sites/default/files/2025-09/2026list_en_final_clean_september_2025.pdf (text read Oct 24, 2026)
Disclaimer
This page is for education and harm reduction. It is not medical advice and not a recommendation to use Efinopegdutide. Please talk to a clinician you trust before making medical decisions, seek care right away for severe stomach pain or repeated vomiting, and report problems to FDA MedWatch (https://www.fda.gov/safety/medwatch).
Approved for Adam Greene by Dr. Nova Reyes, 2026-10-25.