Semaglutide vs Tirzepatide vs Retatrutide

A physician-led comparison of the single-, dual-, and triple-agonist GLP-1 medications — how they work, expected weight loss, side effects, and availability — so you and your doctor can choose the right fit.

Important: retatrutide is investigational

Retatrutide is an investigational triple agonist that is not yet FDA approved. It is covered here for education and comparison only — we don't market or sell it. Any treatment decision is a clinical one made with a licensed physician. The best first step for anyone is a consultation, where a GOAL.MD physician reviews your health and goals and discusses the options appropriate for you.

Single, dual, and triple agonists: what's the difference?

All three medications are once-weekly injections that help with weight loss by acting on the hormones that regulate appetite, digestion, and metabolism — but they differ in how many pathways they target. Semaglutide (Wegovy, Ozempic) is a single-agonist that mimics GLP-1. Tirzepatide (Zepbound, Mounjaro) is a dual-agonist that adds GIP. Retatrutide is an investigational triple-agonist that also targets glucagon, which may further boost energy expenditure and fat metabolism. More pathways can mean a broader metabolic effect — but retatrutide has not completed the trials or FDA review needed to be prescribed.

Efficacy: how much weight can you lose?

Across separate clinical trials, average weight loss has increased with each added pathway. Semaglutide averaged about 15% of body weight over 68 weeks (STEP-1); tirzepatide reached roughly 20–22% at its highest dose over 72 weeks (SURMOUNT-1); and retatrutide reported around 24% at the top dose over 48 weeks in a phase-2 study. Because these figures come from different trials rather than one head-to-head study, they aren't perfectly comparable, and retatrutide's results still require phase-3 confirmation. On paper retatrutide looks the most powerful — but semaglutide and tirzepatide are the proven, available options today.

Side effects and dosing

All three share a similar side-effect profile — most commonly nausea, diarrhea, constipation, and reduced appetite, typically during dose increases and usually improving over time. Each is started low and titrated up slowly so the body can adjust and GI symptoms stay manageable. The more potent options tend to show dose-dependent GI effects, and retatrutide's complete safety profile is still being established in ongoing trials. Smaller, lower-fat meals and good hydration help with any of them.

Availability and which one to choose

The most important practical difference is availability: semaglutide and tirzepatide are FDA-cleared and can be prescribed today, while retatrutide is not yet FDA approved and cannot be obtained through legitimate medical channels. For now, the real decision is between semaglutide and tirzepatide — and the right pick depends on your goals, medical history, side-effect tolerance, and budget, decided with a physician. At GOAL.MD, pricing is transparent and all-inclusive, with no auto-billing. If retatrutide is approved in the future, our physicians will evaluate it as an option.

Frequently asked questions

What is retatrutide and is it FDA approved?

Retatrutide is an investigational, once-weekly injectable that acts on three hormone pathways — GIP, GLP-1, and glucagon — earning it the nickname 'triple agonist' or 'triple-G.' As of now it is NOT FDA approved and remains in clinical trials. Early phase-2 data has been promising, but it must complete phase-3 studies and FDA review before it is broadly available. This guide covers retatrutide for education only — we don't market or sell it.

Retatrutide vs semaglutide: which is better for weight loss?

In separate clinical trials, retatrutide has posted the larger average weight loss — roughly 24% of body weight at the top dose over 48 weeks in a phase-2 study, versus about 15% for semaglutide (Wegovy, Ozempic) over 68 weeks in STEP-1. Retatrutide targets three pathways (GIP, GLP-1, glucagon) while semaglutide targets one (GLP-1). The important caveat: these are different trials, not a head-to-head study, and retatrutide is still investigational, while semaglutide is FDA-cleared and available today.

Retatrutide vs tirzepatide: which is more effective?

Trial data suggests retatrutide may edge out tirzepatide on average weight loss — about 24% at the highest dose (48-week phase-2) compared with roughly 20–22% for tirzepatide (Zepbound, Mounjaro) over 72 weeks in SURMOUNT-1. Retatrutide adds a glucagon target on top of tirzepatide's GIP + GLP-1 action, which may further raise energy expenditure. Because the numbers come from different studies, they aren't perfectly comparable, and only tirzepatide is FDA-approved and prescribable now.

Retatrutide vs Ozempic and Wegovy?

Ozempic and Wegovy are brand names for semaglutide, a single-pathway GLP-1 agonist. Retatrutide is an investigational triple agonist (GIP + GLP-1 + glucagon). In early data retatrutide produced greater average weight loss, but semaglutide has years of real-world use, FDA approval, and established safety data — while retatrutide is still completing trials.

Retatrutide vs Mounjaro and Zepbound?

Mounjaro and Zepbound are brand names for tirzepatide, a dual GIP + GLP-1 agonist. Retatrutide adds a third target, glucagon. Phase-2 retatrutide results have been strong, but tirzepatide is FDA-approved, widely used, and has a well-characterized safety profile, whereas retatrutide's full profile is still being established in ongoing trials.

What is the difference between single, dual, and triple agonists?

Semaglutide is a single-agonist that mimics GLP-1, a hormone that curbs appetite and slows digestion. Tirzepatide is a dual-agonist that activates both GLP-1 and GIP. Retatrutide is a triple-agonist that adds a third target, glucagon, which may further increase energy expenditure and fat metabolism. Each added pathway is thought to broaden the metabolic effect — but also requires careful physician oversight and titration.

How much weight can you lose on retatrutide?

In a phase-2 trial, participants on the highest retatrutide dose lost roughly 24% of their body weight over about 48 weeks, with results still trending downward at the study's end. Those are early, investigational figures that need phase-3 confirmation, and individual results always vary. For proven, available options, semaglutide and tirzepatide have well-documented outcomes.

Do the three medications have different side effects?

All three share a similar GI-focused side-effect profile — nausea, diarrhea, constipation, vomiting, and reduced appetite — most common during dose increases and usually improving over time. In trials, the more potent options (tirzepatide and retatrutide) tended to show dose-dependent GI effects. Retatrutide's full safety profile is still being established in ongoing trials. Slow titration, smaller lower-fat meals, and hydration help with all of them.

Can I get retatrutide right now?

Retatrutide is investigational, so it isn't sold or advertised as a finished weight-loss product, and we don't promote its purchase. Treatment decisions are individual and clinical, though — the right first step is a consultation. During a physician visit, a licensed GOAL.MD doctor reviews your health history and goals and walks you through the full landscape of appropriate options for you. What's suitable for any given patient is a medical decision made in that visit, not something to shop for online.

When will retatrutide be available?

There is no confirmed availability date. Retatrutide is progressing through phase-3 clinical trials, and FDA approval — if granted — typically follows successful completion and regulatory review, which can take a year or more. As the landscape evolves, our physicians continually evaluate what's appropriate; today, semaglutide and tirzepatide are the proven, established choices.

Where should I start my weight-loss journey?

Start with a conversation. Whatever medication ultimately fits, the highest-impact first step is a physician-led evaluation that looks at your health, goals, and lifestyle — paired with nutrition coaching. A GOAL.MD physician reviews your assessment and recommends the right plan for you. You don't need to have a specific medication in mind to begin; the consultation is where the right path becomes clear.

This guide provides general educational information and is not medical advice. Weight-loss results and medication suitability vary by individual health status. Compounded medications are not FDA-approved. All treatments require a physician evaluation and prescription. Talk to a licensed physician before starting or changing any medication.

Medically reviewed by Dr. Michael Mimlitz, MD (NPI 1508891870), Chief Physician of GOAL.MD. Physician-supervised telehealth. More at goal.md/guides.