Survodutide vs Retatrutide: Weight Loss, Side Effects and Status

Survodutide vs retatrutide comes down to one extra receptor and a gap in weight loss. Both drugs activate the GLP-1 and glucagon receptors, and only retatrutide also activates GIP. Counting everyone randomized, retatrutide 12 mg averaged 25.0% weight loss at 80 weeks in TRIUMPH-1, and survodutide 6.0 mg averaged 13.0% at 76 weeks in SYNCHRONIZE-1. Neither drug is approved anywhere, and no trial has put them head to head.

The side-by-side comes first, then the weight numbers with each trial's counting method spelled out, liver data, side effects and each drug's status as of October 2026. For the wider field, see new weight loss drugs.

Survodutide vs retatrutide side by side

Every row below that compares numbers is cross-trial. The people, the lengths and the dose steps differ.

Sources: the TRIUMPH-1 NEJM paper and Lilly release, the TRIUMPH-2 Lancet paper, the SYNCHRONIZE-1 and SYNCHRONIZE-2 NEJM papers and Boehringer's and Zealand Pharma's releases. Survodutide's 16.6% is Boehringer's "up to an average" figure, and the release doesn't say which dose produced it.

How the two drugs differ in mechanism

Glucagon is the shared piece. Its signaling is thought to raise energy use and lower liver fat, which is why both drugs get discussed for fatty liver disease. GLP-1 curbs appetite. The only receptor retatrutide adds is GIP, the one tirzepatide also hits. Lilly describes retatrutide as a single molecule that activates the GIP, GLP-1 and glucagon receptors.

That makes survodutide a test of whether the third receptor matters. Our read: the weight gap in the table is large enough to suggest GIP helps, but the trials differ in dose steps, length and starting weight, so we can't isolate GIP's share. Other GLP-1 and glucagon drugs, like mazdutide, give a second chance to test that idea.

How much weight does survodutide cause compared with retatrutide?

The same drug can look like it lost 13% or 16.6%, depending on how the trial counts. The treatment-regimen estimand counts everyone randomized, including people who stopped. The efficacy estimand assumes everyone stayed on the drug. Boehringer led with the second; the NEJM paper's primary analysis is the first.

In SYNCHRONIZE-1, 725 adults without diabetes got survodutide or placebo for 76 weeks. On the treatment-regimen estimand, weight fell 12.2% on 3.6 mg and 13.0% on 6.0 mg against 5.4% on placebo, and 71.9% of the 6.0 mg group lost at least 5%, against 46.3% on placebo. That placebo group lost more than TRIUMPH-1's (3.9%), which shrinks survodutide's placebo-adjusted gain to about 7.6 points (our subtraction), against 21.0 for retatrutide 12 mg in TRIUMPH-1 (the paper's difference).

In type 2 diabetes the gap holds. Per the SYNCHRONIZE-2 NEJM abstract, survodutide 6.0 mg averaged 9.8% against 3.9% on placebo over 76 weeks (752 participants), with A1C down 0.8 points. In TRIUMPH-2, retatrutide 12 mg averaged 18.8% against 5.1% over 80 weeks, with the paper's difference at 13.8 points. Efficacy-estimand figures from the releases are "up to" 13.1% for survodutide and 20.8% for retatrutide 12 mg, again cross-trial.

Retatrutide's full dose-by-dose numbers are on our retatrutide weight loss results page.

Liver data and MASH

Survodutide has the stronger liver case so far. In its Phase 2 trial in biopsy-proven MASH with fibrosis (NEJM 2024; 293 people, 48 weeks), MASH improved without worsening of fibrosis in 62% on 4.8 mg and 43% on 6.0 mg, against 14% on placebo. Fibrosis improved by one stage or more in 34% to 36% on survodutide against 22% on placebo.

In SYNCHRONIZE-MASLD (Nature Medicine; 216 adults, survodutide 6.0 mg or placebo, 48 weeks), 84.2% on survodutide had at least 30% less liver fat against 24.3% on placebo (efficacy estimand), and 68.5% against 28.6% counting everyone randomized. The Phase 3 MASH trials, LIVERAGE (about 1,800 people, estimated primary completion December 2031) and LIVERAGE-Cirrhosis (about 1,590, June 2029), were still recruiting per ClinicalTrials.gov in October 2026.

Retatrutide's liver data is thinner. A substudy of the Phase 2 obesity trial (Nature Medicine 2024) enrolled 98 people with at least 10% liver fat. At 48 weeks, relative liver fat fell 86.0% on 12 mg against 4.6% on placebo, and 93% of people on 12 mg had normal liver fat (under 5%) by 48 weeks. Scan data covered only 43.9% of participants by then. We found no retatrutide biopsy trial that has reported.

The two sets don't line up. Retatrutide's trial reported average relative change in liver fat; survodutide's Phase 3 reported the share of people with at least a 30% drop. Lilly's SYNERGY-Outcomes trial (NCT07165028) is testing retatrutide in adults with MASLD at higher risk of liver outcomes, but it hasn't reported.

Side effects and stopping rates

Both drugs bring the usual incretin stomach effects. In SYNCHRONIZE-1, gastrointestinal events hit 80.9% on 3.6 mg and 89.7% on 6.0 mg, against 47.9% on placebo; the NEJM abstract calls them typically mild to moderate and reports no deaths. In TRIUMPH-1, 12 mg brought nausea in 42.4% (placebo 14.8%), diarrhea in 32.0% (13.5%), constipation in 26.1% (10.9%) and vomiting in 25.3% (4.8%). Dysesthesia, an oversensitive or burning skin feeling, hit 12.5% on 12 mg against 0.9%. Retatrutide's trials listed symptoms one by one, while survodutide's abstract gives one combined stomach figure, so these can't be matched row for row.

Stopping rates are the better yardstick, and the data is patchy. In TRIUMPH-1, 11.3% on 12 mg stopped for an adverse event, against 4.9% on placebo. In SYNCHRONIZE-2, Zealand Pharma's release says 18% on survodutide (dose not given) stopped for stomach side effects, against 1.2% on placebo, mostly during dose escalation. We couldn't find an adverse-event stopping rate for SYNCHRONIZE-1 in the sources we opened, and the two figures measure different things, so don't treat 18% against 11.3% as a tie-breaker.

For what retatrutide's side effects feel like in practice, see retatrutide side effects.

Dosing and how the trials stepped up

Both are weekly subcutaneous injections in trials. Retatrutide's Phase 3 trials started at 2 mg and rose every 4 weeks; the 12 mg arm in TRIUMPH-1 went through 2, 4, 6 and 9 mg first. Survodutide's SYNCHRONIZE trials gave doses adjusted up to 3.6 mg or 6.0 mg, and the abstracts mention a prolonged escalation period, but we didn't find the step schedule in a source we could open. Dose decisions in a trial belong to the trial team, and neither drug has a label to follow.

Where each drug is in development

Retatrutide has Phase 3 data from six trials. Lilly last said, on September 29, 2026, that it plans to submit retatrutide to the FDA in the first quarter of 2027 as a Biologics License Application (BLA). On October 2, 2026, the FDA decided that retatrutide is a drug, not a biological product, so an application would need to be filed under section 505 of the Federal Food, Drug, and Cosmetic Act. Lilly's appeal on that question is pending in the Seventh Circuit, and we found no ruling as of October 31, 2026. See the retatrutide release date for the timeline.

Survodutide's two obesity trials, SYNCHRONIZE-1 and -2, have reported, and Boehringer said in April 2026 that more results would read out during 2026. Zealand Pharma's October 1 release looks ahead to cardiovascular outcomes results later this year. We found no filing date or regulator submission from Boehringer.

Neither drug can be legally bought outside a trial. Lilly says retatrutide "cannot be legally sold or marketed for human use", so any vial sold as retatrutide for sale online isn't Lilly's product, and the FDA has also warned companies selling unapproved survodutide online.

Which one fits which question?

If the goal is the most weight loss on current data, retatrutide's numbers are ahead, though TRIUMPH-1's people started heavier (112.7 kg against 108.8 kg). If liver disease is the main concern, survodutide has the biopsy and Phase 3 liver-fat data, and a doctor treating MASH would want to know that. Neither choice exists yet outside a trial, and the approved comparison most readers need right now is retatrutide vs tirzepatide.

Ask a doctor which approved drug fits your weight and liver situation today, and check back after Lilly's TRIUMPH-5 trial against tirzepatide reports. It's the first Phase 3 comparison of retatrutide against tirzepatide.