Semaglutide vs Tirzepatide vs Retatrutide Compared
Medically reviewed by Medical Advisory Board Last reviewed 2026-08-03
Single, dual, and triple hormone agonists — one available today, one investigational, both built on the same GLP-1 foundation
Semaglutide (Ozempic/Wegovy), tirzepatide (Mounjaro/Zepbound), and retatrutide are three GLP-1-based weight-loss drugs that target one, two, and three hormone receptors respectively. Semaglutide and tirzepatide are both FDA-approved; retatrutide is still investigational but has shown the largest average weight loss of the three in trials so far. This guide compares all three side by side.
This article is for informational purposes only and is not medical advice. Retatrutide is investigational and not FDA-approved or available for prescribing — consult a physician for medical guidance on any of these medications.
Semaglutide, tirzepatide, and retatrutide sit on the same evolutionary line of GLP-1-based metabolic drugs, each adding one more hormone-receptor target than the last. Semaglutide (Ozempic for diabetes, Wegovy for weight loss) activates only the GLP-1 receptor. Tirzepatide (Mounjaro for diabetes, Zepbound for weight loss) adds a GIP receptor to the mix — a dual agonist. Retatrutide goes one step further, adding a glucagon receptor on top of GIP and GLP-1 — a triple agonist, and still in clinical trials as of 2026, not yet available with a prescription.
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Semaglutide vs Tirzepatide vs Retatrutide: Side-by-Side
| Factor | Semaglutide (Ozempic/Wegovy) | Tirzepatide (Mounjaro/Zepbound) | Retatrutide (investigational) |
|---|---|---|---|
| Receptors targeted | GLP-1 only (single agonist) | GIP + GLP-1 (dual agonist) | GIP + GLP-1 + glucagon (triple agonist) |
| FDA status | Approved (diabetes 2017, weight loss 2021) | Approved (diabetes 2022, weight loss 2023) | Investigational — Phase 3 trials, not yet approved |
| Average weight loss (pivotal trial) | ~14.9% (STEP-1, 68 weeks) | ~20.9% (SURMOUNT-1, 72 weeks) | ~24.2% (Phase 2 trial, 48 weeks, highest dose) |
| Dosing schedule | Weekly injection | Weekly injection | Weekly injection (trial dosing) |
| Cardiovascular outcomes data | SELECT (2023) — 20% MACE reduction | SURMOUNT-MMO ongoing; preliminary data positive | Not yet studied at CV-outcomes scale |
| Available today with a prescription | Yes | Yes | No |
Why Adding Receptors Changes the Results
Each drug in this line adds one more hormone pathway on top of GLP-1, and the trial results track that pattern almost exactly: semaglutide (one receptor) produced the smallest average weight loss, tirzepatide (two receptors) produced meaningfully more, and retatrutide (three receptors) has produced the most in trials run so far. GIP amplifies GLP-1's appetite-suppressing effect and appears to improve fat metabolism directly, which is the main driver of tirzepatide's edge over semaglutide. Adding glucagon receptor activity — retatrutide's distinguishing feature — increases energy expenditure on top of the appetite-suppression effect the other two drugs already provide, which is the leading explanation for its larger trial results.
More receptors targeted isn't automatically "better" for everyone — it also means more potential GI side effects during dose titration, and retatrutide's added glucagon activity is still being studied for its full long-term safety profile, since human data is far more limited than for the two approved drugs.
Availability Is the Deciding Factor Today
The most important practical difference isn't the trial numbers — it's that only two of these three drugs can actually be prescribed right now. Semaglutide and tirzepatide are both FDA-approved and available (subject to insurance, cost, and supply). Retatrutide remains in Phase 3 clinical trials as of 2026, with no confirmed FDA approval date. Anyone considering retatrutide today can only access it through a clinical trial, not a prescription, and compounded or gray-market versions carry meaningful safety and legitimacy risks that FDA-approved drugs don't.
For most people deciding right now, the real choice is between semaglutide and tirzepatide, not a three-way decision — retatrutide is a "watch and wait" option until it clears the FDA process.
The Verdict: How to Think About the Three
Frame the decision by what's actually available to you today:
- If you need a prescription now and cardiovascular risk reduction matters: semaglutide (Wegovy), given its SELECT-trial cardiovascular outcomes data.
- If you need a prescription now and maximizing average weight loss is the priority: tirzepatide (Zepbound), the strongest FDA-approved option available today.
- If you've plateaued on semaglutide or tirzepatide: a switch between the two (see our individual comparison pages) is a real, available option; retatrutide is not, yet.
- If you're simply tracking the pipeline: retatrutide's Phase 3 data is worth watching, but it is not a near-term option for anyone outside a clinical trial.
See our individual comparisons — tirzepatide vs semaglutide, retatrutide vs semaglutide, and retatrutide vs tirzepatide — for the full detail behind each matchup, or take our free assessment to talk through which approved option fits your history.
What to Look For in a Body-Composition Scale
A bioimpedance scale trends body fat and muscle rather than just weight — useful when the number stalls but your composition is improving. The absolute body-fat % isn't lab-accurate, so use it for TRENDS at a consistent time of day. Choose one that syncs to an app so you can watch the trend line.
Frequently Asked Questions
Which produces the most weight loss: semaglutide, tirzepatide, or retatrutide?
In separate trials, retatrutide has produced the largest average weight loss (~24.2% at the highest dose in a 48-week Phase 2 trial), followed by tirzepatide (~20.9% in SURMOUNT-1) and then semaglutide (~14.9% in STEP-1). These are different trials with different populations and follow-up periods, not a single head-to-head study, so the numbers are directional, not a strict ranking.
Is retatrutide FDA-approved like semaglutide and tirzepatide?
No. As of 2026, retatrutide remains in Phase 3 clinical trials and is not FDA-approved or available with a prescription. Semaglutide (Ozempic/Wegovy) and tirzepatide (Mounjaro/Zepbound) are both FDA-approved and available today, subject to insurance and supply.
What's the difference between a single, dual, and triple agonist?
The terms describe how many hormone receptors a drug activates. Semaglutide is a single agonist (GLP-1 only). Tirzepatide is a dual agonist (GIP + GLP-1). Retatrutide is a triple agonist (GIP + GLP-1 + glucagon). Generally, more receptor targets have correlated with more average weight loss in trials so far, though each drug also has its own distinct safety and tolerability profile.
Can I get retatrutide instead of Ozempic or Mounjaro right now?
Not through a standard prescription. Retatrutide is only accessible through enrollment in a clinical trial while it remains investigational. Compounded or gray-market versions exist but carry real safety, quality, and legality risks that FDA-approved semaglutide and tirzepatide products don't, so most clinicians recommend one of the two approved drugs while waiting for retatrutide's approval process to complete.
Should I wait for retatrutide instead of starting semaglutide or tirzepatide now?
For most people, no — there is no confirmed FDA approval date for retatrutide, and delaying treatment has its own metabolic cost. Semaglutide and tirzepatide are both proven, available options today. If you later want to switch to retatrutide once it's approved, that's a conversation to have with your prescriber at that time, not a reason to defer treatment now.
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