On this page
What is the difference between retatrutide, tirzepatide and semaglutide?
The three names refer to different molecules, with different receptor targets and different approval histories. “GLP-3” is an informal nickname for retatrutide’s triple action; it is not the name of an additional GLP receptor.1
| Molecule | Receptor targets | Weight-management context |
|---|---|---|
| Retatrutide | GLP-1, GIP and glucagon | Investigational; studied in clinical trials.1 |
| Tirzepatide | GIP and GLP-1 | Zepbound is an approved prescription product.2 |
| Semaglutide | GLP-1 | Wegovy has approved prescription formulations.3 |
The target count describes how a molecule acts. It does not, by itself, tell you how much weight a particular person will lose. To compare outcomes, match the actual formulation, dose, population and treatment period. Then ask whether the medicines were tested against each other in the same trial.
This guide uses U.S. product labels for dosing and availability. A brand’s formulation or approved use can differ by country, so match any prescription discussion to the local label.
What did the tirzepatide-versus-semaglutide head-to-head trial show?
SURMOUNT-5 directly compared the two medicines. It randomized 751 adults with obesity without type 2 diabetes to weekly injections for 72 weeks. The trial was open-label, meaning participants and researchers knew the assigned treatment.4
| Treatment | Maximum tolerated study dose | Mean weight reduction |
|---|---|---|
| Tirzepatide | 10 or 15 mg weekly | 20.2% |
| Semaglutide | 1.7 or 2.4 mg weekly | 13.7% |
The study found greater average weight and waist reduction with tirzepatide at those regimens.4 The weight difference is 6.5 percentage points, calculated by subtracting the two averages. That is different from saying every participant lost that much more.
The useful advantage of a direct trial is the shared comparison framework. Both groups follow the same study design and assessment period, making the treatment difference easier to interpret than a collection of unrelated headlines.
Does retatrutide produce more weight loss than the other two?
In the published TRIUMPH-1 trial, the retatrutide 12 mg target group averaged 25.0% weight reduction at 80 weeks, versus 3.9% with placebo. The study randomized 2,339 adults without diabetes; those figures use the treatment-regimen analysis, which evaluates the assigned treatment strategy including discontinuation.5
That is substantial weight-loss evidence for retatrutide. It is also a separate trial from SURMOUNT-5, so subtracting its result from the table above would not measure a head-to-head treatment advantage.
TRIUMPH-5 is the dedicated retatrutide-versus-tirzepatide study. Its official record lists an 80-week primary weight endpoint and an active, non-recruiting status. This review includes evidence available by 2 November 2026 and does not include a completed comparative result from that trial.6
When reading a comparison, check four details: who entered the study, how long it ran, which doses were assigned and how the analysis handled stopping treatment. A longer study can answer a different question from a shorter one, and an estimate under continued treatment differs from one that includes discontinuation.
For the outcomes behind retatrutide’s appeal—weight, appetite, waist measurements and body composition—see the retatrutide benefits and research guide.
Does the comparison include Wegovy HD and the Wegovy pill?
The exact semaglutide formulation matters. In March 2026, the FDA approved Wegovy HD, a 7.2 mg weekly injection for weight reduction and maintenance in eligible adults.7 This adds an option beyond the injectable doses used in the earlier head-to-head trial.
The separate STEP UP study compared semaglutide doses in adults with obesity without diabetes. At 72 weeks, mean weight reduction was 18.7% with 7.2 mg, 15.6% with 2.4 mg and 3.9% with placebo under the treatment-policy analysis. That supports a higher-dose comparison within semaglutide; tirzepatide and retatrutide were not study arms.8
Wegovy also has a once-daily tablet formulation, with a 25 mg maintenance dose after escalation. The U.S. pill became available in January 2026 following its December 2025 approval.15
A claim that one molecule “beats Wegovy” should therefore identify which Wegovy dose and formulation was tested. An injection trial cannot automatically settle the comparison with a newer injection dose or an oral product.
How do their weekly schedules and maintenance doses compare?
The numbers below describe trial assignments or approved adult weight-management labels. They show why a milligram number needs a product name and a treatment stage beside it.
| Product or study | Starting stage | Later dose |
|---|---|---|
| Retatrutide, TRIUMPH-1 | 2 mg once weekly | Assigned targets of 4, 9 or 12 mg, reached through four-week escalation steps.9 |
| Zepbound | 2.5 mg weekly for four weeks | Weight-management maintenance doses: 5, 10 or 15 mg weekly. Increases are separated by at least four weeks.2 |
| Wegovy injection | 0.25 mg once weekly | 1.7 mg or the recommended 2.4 mg weekly maintenance dose; selected adults may progress to 7.2 mg.3 |
For the higher Wegovy dose, the label requires at least four weeks of tolerating 2.4 mg and a clinical need for additional weight reduction.3 The table is an overview; the full label contains the intermediate steps and other prescribing details.
A starting amount helps establish the treatment schedule; a maintenance amount describes the later stage. The retatrutide row is a supervised trial protocol, whereas the approved medicines have prescribing instructions. Neither can be selected from a research vial’s total contents.
See retatrutide dosage, titration and reconstitution for its full study schedule and the distinction between milligrams, liquid concentration and device markings.
Compare retatrutide vials and the preloaded pen
10 mg vial · 30 mg vial · 15 mg / 3 mL autoinjector. Check each format’s total quantity and the original vial certificates.
Which side effects matter when comparing the three?
Compare the ability to stay on treatment alongside weight change. In SURMOUNT-5, gastrointestinal effects were the most common adverse events in both groups; most were mild or moderate and occurred mainly during escalation.4
Retatrutide’s TRIUMPH-1 report also describes nausea, diarrhea, constipation, vomiting and altered skin sensations called dysesthesia. In its 12 mg target group, 11.3% stopped because of adverse events, versus 4.9% with placebo.10
STEP UP recorded more gastrointestinal events and dysesthesia with the higher semaglutide dose than with the lower dose.8 A larger target dose therefore brings a tolerability question as well as a potential weight-loss benefit.
The approved labels also require consideration of medical history. Both Zepbound and Wegovy are contraindicated in people with a personal or family history of medullary thyroid carcinoma or MEN 2.23 This is one reason a preference based on headline weight loss is only the beginning of a prescribing discussion.
For a useful comparison, distinguish an uncomfortable symptom from an event that caused treatment to stop. Check how the event was defined and over what period it was counted. Rates from unrelated studies should not be turned into a “safest drug” ranking.
Are these short cycles, or is longer treatment part of the plan?
Maintenance deserves the same attention as the first months of weight loss. In SURMOUNT-4, participants who continued tirzepatide after an initial treatment period maintained and extended their reduction; those switched to placebo regained substantial weight. This was a randomized withdrawal study.11
A semaglutide STEP 1 extension also observed weight regain after stopping treatment. It followed a selected trial-completer group after both study medication and lifestyle support ended, so its design differs from the tirzepatide withdrawal trial.12
For retatrutide, TRIUMPH-6 is studying continued treatment, a lower dose and a switch to placebo after an 80-week lead-in. Its further 36-week comparison is a maintenance-study design, not a published prediction of post-treatment regain.13
The practical questions are how progress will be reviewed, what the maintenance goal is and what support remains if treatment changes. A plan based only on finishing one container leaves those questions unanswered. Treatment duration and a product’s supply duration are different calculations.
Can the doses be converted, combined or swapped?
There is no arithmetic conversion in this comparison. A milligram is a measure of mass, not a standardized unit of appetite effect. Matching the number on two different molecules does not establish matching effects or tolerability.
A tablet amount, an injectable weekly amount and a container’s total contents also describe different things. Do not turn a comparison table into a switching schedule. A prescriber needs the exact product, last dose, time on that dose, treatment response and any side effects to assess a change.
The Zepbound label does not recommend combining it with another tirzepatide product or a GLP-1 receptor agonist.2 Adding a research peptide does not create a validated combined regimen.
A useful medication record names the molecule, brand or source, formulation, strength and dates. “A pen” or “a few units” is not enough information to identify a dose.
How do the retatrutide vial and pen formats compare?
The retatrutide range displayed on this site contains 10 mg and 30 mg powder vials and a 15 mg / 3 mL preloaded pen. The pen’s stated concentration is 5 mg/mL. Those figures describe the containers; they do not choose a clinical weekly amount.
For product comparisons, record three separate values: total peptide, solution volume when applicable and documented concentration. A larger vial contains more material, while a preloaded format changes the preparation workflow. Neither feature establishes that a product is equivalent to the investigational medicine used in a trial.
Open the retatrutide product formats to inspect the original imagery, specifications and Buy buttons. The quality and COA section includes the original vial reports and explains their testing scope. Match a document to the exact lot and format; a vial report does not automatically describe a finished pen.
The FDA states that retatrutide cannot be used in compounding under U.S. federal law. A research listing is therefore a different category from an approved weight-management prescription.14
What should you compare before discussing a treatment choice?
Start with the decision you want the comparison to support. “Which produced more average weight loss in a particular trial?” is a research question. “Which fits my treatment goals and medical history?” needs an individual prescribing assessment.
| Question | What to bring or check |
|---|---|
| What is the goal? | Weight trend, waist measurements, daily function and the health outcomes that matter to you. |
| Which exact product is being discussed? | Molecule, formulation, dose stage, local indication and current label. |
| What happened with previous treatment? | Duration, response, symptoms and reasons for stopping or changing it. |
| What will continuing treatment involve? | Follow-up appointments, monitoring, supply and the maintenance discussion. |
| What is the actual cost over the same period? | Compare written quotes for the same number of weeks and include required consultations or supplies. |
For personal progress tracking, use consistent measurement conditions and record changes in eating, activity and other treatment. A result becomes more informative when you know both what changed and the circumstances around it.
What are the most common comparison questions?
Does triple action mean three times the weight loss?
No. Receptor count is a description of mechanism, not a multiplier. Weight change must be measured in people, with the dose, time point and population specified.
Can I compare before-and-after photographs instead of studies?
Photos can document appearance, but they do not identify the treatment contribution. Dates, measurements, treatment history and other changes provide context that a photograph alone cannot supply.
Is a product’s price per milligram a fair comparison between molecules?
It is a quantity comparison, not a comparison of treatment value. Different molecules and formulations use different schedules. Compare the actual prescribed supply period and associated care costs instead.
Where can I read more about retatrutide itself?
Use the benefits guide for outcomes and body composition, the dosage guide for study schedules and measurements, and the product section for the displayed formats and Buy buttons.
Sources and original records
Original research, official prescribing information and named product documents. Each numerical result refers to the stated population, timeframe and analysis.
- 01Retatrutide terminology, receptor targets and development status ↗
Lilly. Official developer information; status reviewed 2 November 2026. Later-dated trial announcements are excluded.
- 02Zepbound U.S. prescribing information ↗
Eli Lilly label, DailyMed. Updated 28 August 2026. Targets, adult dosing, contraindications and coadministration.
- 03Wegovy U.S. prescribing information ↗
Novo Nordisk label, DailyMed. Updated 18 June 2026. Injectable and tablet formulations, dosing and contraindications.
- 04SURMOUNT-5: tirzepatide compared with semaglutide ↗
Aronne et al. NEJM, 11 May 2025. Direct 72-week comparison in adults with obesity without type 2 diabetes.
- 05TRIUMPH-1: published retatrutide phase 3 results ↗
Jastreboff et al. NEJM, 29 September 2026. Treatment-regimen results at 80 weeks.
- 06TRIUMPH-5: retatrutide versus tirzepatide trial record ↗
NCT06662383. Registry updated 20 July 2026; active, not recruiting. Study design, not a completed result in this review.
- 07FDA approval of Wegovy HD 7.2 mg ↗
FDA, 19 March 2026. Approval of the higher weekly semaglutide injection for eligible adults.
- 08STEP UP: semaglutide 7.2 mg versus 2.4 mg and placebo ↗
Wharton et al. Lancet Diabetes & Endocrinology, 14 September 2025. Adults with obesity without diabetes; 72-week treatment-policy analysis.
- 09TRIUMPH-1 study dose escalation ↗
Lilly, 21 May 2026. Starting dose, four-week escalation and assigned targets.
- 10TRIUMPH-1 tolerability details ↗
Lilly, 6 June 2026. Retatrutide adverse events and discontinuation; TRIUMPH-1 population.
- 11SURMOUNT-4: continued tirzepatide and treatment withdrawal ↗
Aronne et al. JAMA, published 11 December 2023. Randomized maintenance and withdrawal study.
- 12STEP 1 extension: weight change after semaglutide withdrawal ↗
Wilding et al. Diabetes, Obesity and Metabolism, 2022. Exploratory follow-up after medication and lifestyle support ended.
- 13TRIUMPH-6 retatrutide maintenance study ↗
Lilly trial record, NCT06859268. Maintenance study design; reviewed 2 November 2026.
- 14FDA information on unapproved GLP-1 weight-loss products ↗
FDA. Retatrutide approval and U.S. compounding status; reviewed 2 November 2026.
- 15U.S. launch of the Wegovy tablet formulation ↗
Novo Nordisk, 5 January 2026. Tablet availability, maintenance strength and approval timing.