Survodutide: What the Phase 3 Evidence Shows

Survodutide is an experimental once-weekly injection from Boehringer Ingelheim, licensed from Zealand Pharma, that switches on two hormone receptors: GLP-1, the target of semaglutide, and glucagon.^[5] In its first phase 3 obesity trial, adults without diabetes lost 12.2% to 13.0% of their body weight over 76 weeks, against 5.4% on placebo.^[3] People with type 2 diabetes lost less, 8.2% to 9.8%.^[4] Gut side effects were very common, and the drug also cut liver fat sharply. It is not approved anywhere, and Boehringer has not announced when it will file for approval.^[8]

What survodutide is

Survodutide, code name BI 456906, is a peptide given as a weekly injection under the skin. It belongs to Zealand Pharma, which licensed it to Boehringer Ingelheim; Boehringer alone runs development and would sell it worldwide.^[5] Zealand would earn royalties on sales.^[9]

Its design is the interesting part. Approved drugs like semaglutide act on the GLP-1 receptor, and tirzepatide adds a second hormone, GIP. Survodutide pairs GLP-1 with glucagon instead. Glucagon is best known for raising blood sugar, which sounds like the wrong direction for a diabetes drug. The reason to target it is that glucagon also acts directly on the liver and on how the body burns energy. Boehringer says it is designed to curb appetite, improve blood sugar control and reduce liver fat.^[8] Retatrutide, Lilly’s candidate, hits all three receptors; our retatrutide evidence review covers that drug.

How much weight people lost

Four controlled trials have now reported weight results in journals. The table uses each paper’s main analysis, which counts everyone who started, including people who stopped the drug.

In SYNCHRONIZE-1, about 72% of people on either dose lost at least 5% of their weight, compared with 46.3% on placebo.^[3] In SYNCHRONIZE-2, the figures were 57.6% and 64.5% against 35.1%, and HbA1c, a measure of long-term blood sugar, fell by 0.9 and 0.8 points from a starting average of 7.4%, against 0.2 on placebo.^[4] The higher dose added little weight loss over the lower one in the trial without diabetes; our analysis newer is not stronger looks at what that extra dose cost in side effects.

Why you may see 16.6% instead

The companies headline larger numbers: up to 16.6% for SYNCHRONIZE-1 and up to 13.1% for SYNCHRONIZE-2.^[9][8] Those come from the “efficacy estimand,” which Boehringer defines as the effect “assuming patients remained on treatment for the entire study duration.”^[8] In other words, it sets aside the people who stopped. That is a fair question to ask (what does the drug do if you keep taking it?), but it is not what happened to everyone who started. The journal papers lead with the lower, all-comers figure, and so do we.

Side effects

Like every GLP-1 drug, survodutide mostly causes stomach and gut problems: nausea, vomiting, diarrhea and constipation. They were usually mild to moderate and showed up mostly while the dose was being raised. But they were more common than many readers will expect, and they made a noticeable share of people stop.

Roughly one in five people on survodutide stopped because of gut side effects across the phase 3 trials, several times the placebo rate. Boehringer says the trial rules allowed little flexibility in slowing the dose increase, and that newer trials use gentler titration.^[8] That is plausible, but it is not yet shown. On the serious end, the phase 3 obesity trial reported no deaths,^[3] and in the phase 2 liver trial serious adverse events occurred in 8% on survodutide and 7% on placebo.^[2]

Heart rate: the glucagon question

Glucagon in high doses speeds up the heart and raises blood pressure, which is why cardiologists watch this drug class closely. One dual agonist from another company was dropped partly because of large heart-rate increases.^[7] So far survodutide looks similar to existing GLP-1 drugs. A review in the Journal of the American Heart Association found that survodutide and its peers raised heart rate about as much as GLP-1 drugs alone, and also lowered blood pressure.^[7] In SYNCHRONIZE-MASLD, resting heart rate rose by 3.6 beats per minute on survodutide versus 0.8 on placebo at week 52, with no case of the dangerous QT prolongation regulators look for; systolic blood pressure fell 7.4 mmHg more than on placebo.^[5] Our guide to GLP-1 drugs and heart rate explains why a few extra beats per minute is a known class effect.

The bigger answer is coming. SYNCHRONIZE-CVOT, a heart-safety trial measuring heart attacks, strokes and related events,^[6] finished with 5,531 participants and a primary completion date of June 2026.^[13] Boehringer says it expects to present the results later in 2026.^[8]

The liver data (MASH and fatty liver)

Liver disease may be where survodutide stands out. MASH, short for metabolic dysfunction-associated steatohepatitis, is the inflamed, scarring form of fatty liver disease. In a 48-week phase 2 trial of 293 people with biopsy-confirmed MASH, the disease improved without worsening scarring in 47%, 62% and 43% of people on the three doses, against 14% on placebo.^[2] Scarring improved by at least one stage in 34% to 36% on survodutide and 22% on placebo, a smaller gap.^[2]

The phase 3 SYNCHRONIZE-MASLD trial then measured liver fat by MRI. Counting everyone who started, 68.5% on survodutide cut their liver fat by at least 30%, against 28.6% on placebo.^[5] Its main results were measured at 48 weeks and it recruited in just two countries, limits its authors acknowledge.^[5]

FDA has given survodutide Fast Track designation (May 2021) and Breakthrough Therapy designation (September 2024) for MASH with moderate or advanced scarring.^[8] Those designations speed up FDA’s process; they are not approvals. The phase 3 trial that would support a MASH approval, LIVERAGE, is enrolling patients now; its registry entry puts the main results at the end of 2031.^[12] For the approved options and the wider evidence, see GLP-1 drugs and fatty liver disease.

Is survodutide approved, and when might it be?

No. Boehringer’s own October 2026 release says survodutide “has not been approved for use, and its efficacy and safety have not been established.”^[8] Neither Boehringer nor Zealand has published a date for filing it with FDA. What the companies have said points to what comes first:

• Heart-safety results. SYNCHRONIZE-CVOT results are expected later in 2026.^[8]
• More obesity and diabetes trials. Boehringer has launched SYNCHRONIZE-T2D, a further phase 3 trial in type 2 diabetes, and has phase 3 trials in Japan and China.^[8]
• Liver trials. The two LIVERAGE phase 3 trials in MASH are recruiting.^[12]

Sites quoting an approval year are estimating, not reporting. Our GLP-1 pipeline tracker follows survodutide alongside the other late-stage drugs and is updated as results and filings land.

What is still unknown

• Heart outcomes. A few beats per minute is reassuring in the short term, but only SYNCHRONIZE-CVOT can show whether the drug is safe, or even protective, for the heart over years.^[6]
• Whether the liver results hold up on biopsy at scale. The strong MASH results come from a 48-week phase 2 trial; the large biopsy-based phase 3 trials are years from finishing.^[2][12]
• Muscle versus fat. Boehringer reports that in a 75-person body-scan substudy of SYNCHRONIZE-1, muscle made up no more than 10% of the tissue lost.^[8] That is company-reported and comes from a small group; it has not been published in full.
• Tolerability with slower dosing. Whether gentler dose increases cut the one-in-five dropout rate is what the newer trials are testing.^[8]

Survodutide sold online

Even with no approval, survodutide is sold online as a “research peptide.” FDA names it directly. On its page about unapproved GLP-1 drugs, the agency lists survodutide with semaglutide, tirzepatide, retatrutide and mazdutide as drugs it has warned sellers about for marketing them to consumers, with dosing instructions, under false “research” or not-for-human-use labels. It tells people not to buy them.^[10] Our FDA warning-letter tracker holds two letters to sellers that listed survodutide by name, among them Xcel Research (December 2024), which sold it as “SURVODUTIDE” alongside retatrutide and mazdutide, and NuScience Peptides (August 2026). FDA called each of those products an unapproved new drug.^[14][15]

It is not a legitimate compounded drug either. Under federal law a pharmacy may compound only with an ingredient that has an official USP or NF standard, is part of an FDA-approved drug, or is on FDA’s 503A bulks list.^[11] Survodutide is not part of any approved drug and is not on that list. Our explainers on whether peptides are legal and what cannot legally be compounded cover the rules. A vial bought online has no prescriber, no pharmacy and no check on what is inside it.

Survodutide vs retatrutide

Both drugs use glucagon; retatrutide adds GIP as a third target. They have never been tested against each other, and their trials enrolled different people for different lengths of time, so their headline numbers cannot be ranked directly. Our side-by-side, survodutide vs retatrutide, sets out what each has shown and where the comparison breaks down.