The short answer
Survodutide activates two receptors, GLP-1 and glucagon; retatrutide activates those two and GIP as well. Neither is approved. In their own phase 3 trials, survodutide averaged 12–13% weight loss at 76 weeks counting everyone, and retatrutide’s top dose about 25–28% at 80 weeks.
Side by side
| Compared | Survodutide | Retatrutide |
|---|---|---|
| Category | Metabolic & GLP-1 | Metabolic & GLP-1 |
| Also known as | BI 456906, BI456906, Survo | LY3437943 |
| What it is | A weekly shot that activates two receptors: GLP-1, for appetite and blood sugar, and glucagon, which clears fat from the liver and, in mice, raises energy use. | The first triple agonist to reach phase 3: it activates GLP-1, GIP and glucagon receptors at once, and the glucagon arm adds extra calorie burn (shown in mice). |
| How it works | Glucagon and GLP-1 receptor dual agonist: a 29-amino-acid peptide built on the glucagon sequence, carrying a C18 fatty acid that binds albumin for once-weekly dosing. It fully activates the GLP-1 receptor (appetite, insulin) and partly activates the glucagon receptor, which raises energy expenditure (shown in mice) and draws down liver fat (the liver-fat drop is measured in people). Developed by Boehringer Ingelheim with Zealand Pharma; its phase 3 (SYNCHRONIZE) results were published in 2026, and it is not approved. | Triple GIP/GLP-1/glucagon receptor agonist. Produces large weight loss through appetite suppression and improved metabolic function; the glucagon arm adds energy expenditure, shown so far in mice. Its trials step the dose up every 4 weeks because GI side effects rise with the dose; in phase 2 they were milder with a 2 mg start than a 4 mg one. |
| Commonly reported | Less appetite and early fullness, with nausea or vomiting during the long dose climb and a resting heart rate a few beats higher. Average weight loss at 76 weeks was 12–13% counting everyone and up to 16.6% for people who stayed on it, and most people in its liver trial cut their liver fat by at least 30%. | Appetite suppression even stronger than tirzepatide, GI side effects after each step-up, and a higher resting heart rate. Its top dose averaged about 25–28% weight loss at 80 weeks in phase 3; it isn't approved yet. |
| Studied range | Research range: 0.3–6 mg, starting dose 0.3 mg. Studied in research — not a recommendation. | Research range: 1–12 mg, starting dose 2 mg. Studied in research — not a recommendation. |
| How often | Weekly | Weekly |
| Half-life | Long enough for once-weekly dosing: a fatty-acid chain binds it to albumin; phase I measured it in people (Jungnik 2023), but the figure is not in the trial summaries | ~6 days (measured in early trials in people) |
| Route | SubQ injection | SubQ injection |
| Typical run | Phase 3 trials run it continuously for 76 weeks after a slow climb of about 24 weeks. Not approved; Boehringer Ingelheim expects its cardiovascular outcomes trial to report later in 2026. | Phase 3 trials use continuous dosing. Community mirrors this — long-term with slow titration. |
| Evidence | Established: clinical trials or FDA-approved use exists | Established: clinical trials or FDA-approved use exists |
| Common side effects | Nausea, vomiting, diarrhea, constipation, decreased appetite, fatigue, higher resting heart rate | Nausea, vomiting, diarrhea, constipation, decreased appetite, fatigue, abdominal pain |
- Category
- SurvodutideMetabolic & GLP-1
- RetatrutideMetabolic & GLP-1
- Also known as
- SurvodutideBI 456906, BI456906, Survo
- RetatrutideLY3437943
- What it is
- SurvodutideA weekly shot that activates two receptors: GLP-1, for appetite and blood sugar, and glucagon, which clears fat from the liver and, in mice, raises energy use.
- RetatrutideThe first triple agonist to reach phase 3: it activates GLP-1, GIP and glucagon receptors at once, and the glucagon arm adds extra calorie burn (shown in mice).
- How it works
- SurvodutideGlucagon and GLP-1 receptor dual agonist: a 29-amino-acid peptide built on the glucagon sequence, carrying a C18 fatty acid that binds albumin for once-weekly dosing. It fully activates the GLP-1 receptor (appetite, insulin) and partly activates the glucagon receptor, which raises energy expenditure (shown in mice) and draws down liver fat (the liver-fat drop is measured in people). Developed by Boehringer Ingelheim with Zealand Pharma; its phase 3 (SYNCHRONIZE) results were published in 2026, and it is not approved.
- RetatrutideTriple GIP/GLP-1/glucagon receptor agonist. Produces large weight loss through appetite suppression and improved metabolic function; the glucagon arm adds energy expenditure, shown so far in mice. Its trials step the dose up every 4 weeks because GI side effects rise with the dose; in phase 2 they were milder with a 2 mg start than a 4 mg one.
- Commonly reported
- SurvodutideLess appetite and early fullness, with nausea or vomiting during the long dose climb and a resting heart rate a few beats higher. Average weight loss at 76 weeks was 12–13% counting everyone and up to 16.6% for people who stayed on it, and most people in its liver trial cut their liver fat by at least 30%.
- RetatrutideAppetite suppression even stronger than tirzepatide, GI side effects after each step-up, and a higher resting heart rate. Its top dose averaged about 25–28% weight loss at 80 weeks in phase 3; it isn't approved yet.
- Studied range
- SurvodutideResearch range: 0.3–6 mg, starting dose 0.3 mg. Studied in research — not a recommendation.
- RetatrutideResearch range: 1–12 mg, starting dose 2 mg. Studied in research — not a recommendation.
- How often
- SurvodutideWeekly
- RetatrutideWeekly
- Half-life
- SurvodutideLong enough for once-weekly dosing: a fatty-acid chain binds it to albumin; phase I measured it in people (Jungnik 2023), but the figure is not in the trial summaries
- Retatrutide~6 days (measured in early trials in people)
- Route
- SurvodutideSubQ injection
- RetatrutideSubQ injection
- Typical run
- SurvodutidePhase 3 trials run it continuously for 76 weeks after a slow climb of about 24 weeks. Not approved; Boehringer Ingelheim expects its cardiovascular outcomes trial to report later in 2026.
- RetatrutidePhase 3 trials use continuous dosing. Community mirrors this — long-term with slow titration.
- Evidence
- SurvodutideEstablished: clinical trials or FDA-approved use exists
- RetatrutideEstablished: clinical trials or FDA-approved use exists
- Common side effects
- SurvodutideNausea, vomiting, diarrhea, constipation, decreased appetite, fatigue, higher resting heart rate
- RetatrutideNausea, vomiting, diarrhea, constipation, decreased appetite, fatigue, abdominal pain
Typical run: Community practice — opinions vary. Not a clinical recommendation.
Week by week
Each entry’s cards by day window, as the compound pages show them. Day 1 is the day you start it.
Survodutide
- Day 1–14 · 0.3 mg The 0.3 mg start
- Day 15–168 The slow climb
- Day 99+ · 3.6 mg 3.6 mg, the lower phase 3 dose
- Day 141+ · 6 mg 6.0 mg, the top phase 3 dose
- Day 169–336 Liver fat: where the glucagon arm shows
Retatrutide
- Day 1–28 · 2 mg Triple-agonist is kicking in
- Day 29–84 · 4 mg Dose-response steepens
- Day 60+ · 9 mg Watch for dysesthesia at higher doses
- Day 84+ This is a maintenance medication, not a course
- Day 85–168 · 8 mg Higher steps: strong satiety
- Day 169–336 No plateau yet at week 48
- Day 337–476 Phase 3 territory: the headline numbers
Questions people ask
How long do survodutide and retatrutide last?
The half-life of survodutide is long enough for once-weekly dosing: a fatty-acid chain binds it to albumin; phase I measured it in people (Jungnik 2023), but the figure is not in the trial summaries. The half-life of retatrutide is ~6 days (measured in early trials in people).
How often are survodutide and retatrutide taken?
Survodutide: weekly. Route: SubQ injection. Retatrutide: weekly. Route: SubQ injection.
How are survodutide and retatrutide dosed in research?
The research range for survodutide is 0.3–6 mg, with a 0.3 mg starting dose. The research range for retatrutide is 1–12 mg, with a 2 mg starting dose. Studied in research — not a recommendation.
What are the common side effects of survodutide and retatrutide?
For survodutide, the library lists: nausea, vomiting, diarrhea, constipation, decreased appetite, fatigue, higher resting heart rate. For retatrutide: nausea, vomiting, diarrhea, constipation, decreased appetite, fatigue, abdominal pain.
Each one in full
PepVault for iPhone
Track either one in PepVault
Log every dose of survodutide or retatrutide, with reminders on your schedule. 7 days free on the yearly plan for new subscribers.
