Retatrutide vs Tirzepatide
Retatrutide and tirzepatide are Eli Lilly's two flagship next-generation obesity peptides — closely related 39-amino-acid molecules with one defining difference. Tirzepatide is a dual GIP/GLP-1 receptor agonist, FDA-approved as Mounjaro (type 2 diabetes) and Zepbound (chronic weight management, and obstructive sleep apnea in adults with obesity). Retatrutide adds a third receptor — glucagon — and is the first triple agonist to complete pivotal Phase 3 obesity trials: TRIUMPH-1 (NEJM, September 2026) reported 25.0% mean weight loss at 12 mg over 80 weeks, and TRIUMPH-2 (Lancet, September 2026) reported 18.8% in adults with type 2 diabetes. Retatrutide is not FDA-approved; Lilly plans to submit it to the FDA in Q1 2027. This comparison is the honest 'dual vs triple' breakdown, with the trade-offs that the cross-trial weight-loss numbers conceal.
Tirzepatide is the proven, commercially available standard: FDA-approved for type 2 diabetes (Mounjaro), chronic weight management (Zepbound), and obstructive sleep apnea in obesity; head-to-head superiority over semaglutide in SURMOUNT-5 (20.2% vs 13.7%); published maintenance-dose data; and growing pleiotropic data in cardiovascular, renal, NASH, HFpEF, and OSA endpoints. Retatrutide is the investigational triple agonist with the larger weight-loss numbers, produced by adding glucagon-receptor agonism to drive hepatic fat oxidation and thermogenesis on top of the dual GIP/GLP-1 appetite suppression. In Phase 3 TRIUMPH-1 (NEJM, September 2026) it produced 25.0% mean weight loss at 12 mg over 80 weeks, against 20.9% for tirzepatide 15 mg over 72 weeks in SURMOUNT-1. Both figures use the same treatment-regimen estimand, but they come from different trials, so this is a cross-trial comparison, not a head-to-head result. The gap looks similar in type 2 diabetes (18.8% in TRIUMPH-2 vs 14.7% in SURMOUNT-2). The caveats are real: the head-to-head trial (TRIUMPH-5) has not reported, retatrutide raises resting heart rate somewhat more, Phase 3 surfaced a dose-related dysesthesia (abnormal skin sensation) signal, its cardiovascular-outcome data are so far inconclusive, and it is not FDA-approved (Lilly plans to submit in Q1 2027). For most patients today the choice is straightforward — tirzepatide is the option that actually exists in the pharmacy. Retatrutide will be the consequential decision once it's approved, especially in patients where the extra ~4 percentage points of weight loss or the glucagon-driven liver-fat reduction matters more than the longer safety record tirzepatide has accumulated.
Retatrutide
An investigational triple agonist (GIP/GLP-1/glucagon) from Eli Lilly. Not FDA-approved. In Phase III TRIUMPH-1 (NEJM, September 2026) the 12 mg dose produced 25.0% mean weight loss at 80 weeks, and TRIUMPH-2 (Lancet, September 2026) showed up to 18.8% in adults with obesity and type 2 diabetes. Lilly plans to file with the FDA in Q1 2027.
Tirzepatide
A dual GIP/GLP-1 receptor agonist FDA-approved for diabetes and weight management, producing the largest weight loss seen in clinical trials.
| Category | Retatrutide | Tirzepatide |
|---|---|---|
| Receptor Mechanism | Triple agonist — GIP + GLP-1 + glucagon | Dual agonist — GIP + GLP-1 |
| Molecule | 39-amino-acid synthetic peptide (LY3437943) with C-20 fatty diacid for albumin binding | 39-amino-acid synthetic peptide (LY3298176) with C-20 fatty diacid for albumin binding |
| Sponsor | Eli Lilly (investigational) | Eli Lilly (commercial — Mounjaro / Zepbound) |
| FDA Status | Not approved. The pivotal Phase 3 obesity trials were published in September 2026 (TRIUMPH-1 in NEJM, TRIUMPH-2 in the Lancet), and Lilly plans to submit to the FDA in Q1 2027, which puts any approval in 2027 at the earliest. Access outside clinical trials is limited to a US compassionate-use pathway opened in mid-2026. | FDA-approved as Mounjaro (T2D, May 2022) and Zepbound (chronic weight management, November 2023; obstructive sleep apnea in obesity, December 2024). |
| Headline Weight Loss | 25.0% mean at 12 mg over 80 weeks in Phase 3 TRIUMPH-1 (NEJM 2026; 17.6% at 4 mg and 23.7% at 9 mg, vs 3.9% on placebo; treatment-regimen estimand). TRIUMPH-4 (Lilly topline, December 2025; obesity with knee osteoarthritis, 68 weeks) reported 28.7% at 12 mg on the efficacy estimand and 23.7% on the treatment-regimen estimand. Phase 2 (NEJM 2023, Jastreboff et al.): 24.2% at 12 mg over 48 weeks. | 20.9% at 15 mg over 72 weeks in SURMOUNT-1 (Phase 3; treatment-regimen estimand, vs 3.1% on placebo); 20.2% over 72 weeks in SURMOUNT-5 head-to-head vs semaglutide (13.7%) |
| Direct Head-to-Head Trial | Under way, not yet reported. TRIUMPH-5 (NCT06662383) randomizes about 800 adults with obesity to retatrutide or tirzepatide, with estimated primary completion in November 2026. Until it reports, every retatrutide-vs-tirzepatide comparison is cross-trial. | Same trial. Cross-trial figures differ in trial duration (80 vs 72 weeks), populations, and placebo response, so the size of any real-world gap is unknown until TRIUMPH-5 reports. |
| Type 2 Diabetes (HbA1c and Weight) | Phase 3 TRIUMPH-2 (Lancet 2026; obesity with T2D, baseline HbA1c 7.7%): HbA1c fell 1.4–1.6 points vs 0.2 on placebo (Lilly-reported, efficacy estimand), and weight fell 11.9%, 16.8%, and 18.8% at 4, 9, and 12 mg vs 5.1% at 80 weeks (treatment-regimen estimand). TRANSCEND-T2D-1 (Lancet, June 2026; monotherapy, 40 weeks): HbA1c -1.69% to -1.94% vs -0.81% on placebo. Phase 2: up to -2.02% at 36 weeks. | -2.0 to -2.4% HbA1c across SURPASS-1 through SURPASS-5 in T2D; superior to semaglutide 1 mg in SURPASS-2 (-2.30% vs -1.86%). In SURMOUNT-2 (obesity with T2D, 72 weeks), weight fell 12.8% at 10 mg and 14.7% at 15 mg vs 3.2% on placebo (treatment-regimen estimand). |
| MASH / Liver Fat | Phase 2a MASLD substudy (Sanyal et al., Nature Medicine 2024): relative liver-fat reduction of 81–82% at 24 weeks on 8–12 mg, with liver fat normalized (below 5%) in 79–86% of participants vs 0% on placebo. Measured by MRI, not biopsy, so this is fat clearance rather than proven MASH resolution; histology-based MASH results are still pending. Glucagon-driven hepatic fat oxidation is the mechanistic differentiator here. | SYNERGY-NASH Phase 2 showed superior fibrosis improvement and MASH resolution versus placebo; effective but without the glucagon-receptor liver-fat oxidation that retatrutide adds |
| OSA | Not an approved indication. In the TRIUMPH-1 OSA substudy (NEJM 2026; 243 adults with obesity and OSA), the apnea-hypopnea index fell by about 34 and 32 events per hour at 9 and 12 mg vs about 10 on placebo over 80 weeks (ITT). An OSA trial within TRIUMPH-2 has not yet reported. | FDA-approved December 2024 for moderate-to-severe OSA in adults with obesity, on the strength of SURMOUNT-OSA Phase 3 data |
| Cardiovascular Outcomes | No completed outcome trial. TRIUMPH-3 (Lilly topline, July 2026; severe obesity with established cardiovascular disease) met its weight endpoints, but MACE events were fewer than anticipated and its cardiovascular hazard ratios were inconclusive. The dedicated cardiovascular and kidney outcomes trial, TRIUMPH-Outcomes (NCT06383390, about 10,000 participants), is ongoing with estimated completion in 2029. | SURPASS-CVOT (13,165 adults with T2D and established cardiovascular disease, median 4 years) found tirzepatide non-inferior to dulaglutide on a composite cardiovascular outcome; a pre-specified exploratory analysis (2026, Lancet Diab Endo) showed a 23% reduction in major kidney events vs dulaglutide. The placebo-controlled outcome trial in obesity without diabetes (SURMOUNT-MMO) is ongoing. |
| Body Composition | Phase 2 DXA substudy in T2D (Coskun et al., Lancet Diabetes Endocrinol 2025): total fat mass fell up to 26% at 36 weeks, and the share of weight lost as lean mass was similar to other obesity treatments. Whether the larger weight loss at 12 mg comes with proportionally more lean-mass loss remains under study. | SURMOUNT-1 body-composition data: lean mass typically 25–40% of total weight loss, with the remainder fat mass; ratio broadly comparable to other major weight-loss interventions |
| Maintenance Strategy | No published withdrawal or dose-reduction data yet. TRIUMPH-6 (NCT06859268; about 640 adults with obesity) gives everyone retatrutide for 80 weeks, then randomizes them to continue, switch to a second dose, or stop (placebo) for 36 weeks; estimated primary completion is 2028. Until it reports, weight regain after stopping is assumed to mirror other incretin drugs. | SURMOUNT-MAINTAIN (2026, Lancet): a 5 mg maintenance dose after the maximum tolerated dose preserved -16.6% from baseline at 112 weeks, versus -9.9% on placebo and -21.9% continuing the MTD. Dose reduction works; stopping doesn't. |
| Dosing | Once-weekly SC, investigational (trial protocols, not labeling). Phase 2 used 1, 4, 8, and 12 mg. Phase 3 TRIUMPH uses 4, 9, and 12 mg maintenance doses, starting at 2 mg and stepping up every 4 weeks (2 → 4 → 6 → 9 → 12 mg) | Once-weekly SC. 2.5 mg starting dose, titrated through 5, 7.5, 10, 12.5, and 15 mg at 4-week intervals as tolerated |
| GI Tolerability | Class-typical incretin GI profile — nausea, vomiting, diarrhea, constipation — dose-related and concentrated at titration. In TRIUMPH-1 (Lilly topline), nausea affected 29–42% across doses vs 15% on placebo, and vomiting 11–25% vs 5%. Discontinuation for adverse events was 4–11% vs 5% on placebo in TRIUMPH-1 and 4–12% vs 5% in TRIUMPH-2. | Class-typical — nausea (~30% at the higher maintenance doses), vomiting, diarrhea, constipation. Generally well-managed with slow titration and dietary adjustment. |
| Cardiac Effects (Beyond MACE) | Modest, dose-dependent resting heart-rate elevation (in Phase 2 it peaked around week 24 and then declined; a 2026 meta-analysis puts it at about +3.5 bpm vs placebo, against about +2 bpm for tirzepatide), attributed partly to the glucagon-receptor component. In Phase 3 TRIUMPH-2, hypotension was more frequent than on placebo (1–6% vs <1%). | Modest resting heart-rate elevation — a mean increase of 1–3 bpm vs no increase on placebo in the Zepbound label's pooled SURMOUNT-1/SURMOUNT-2 data; class effect of GLP-1 agonism. Not associated with increased arrhythmia or MACE in completed trials. |
| Glycemic Profile Caveat | The glucagon-receptor component can produce transient HbA1c excursions or modest hyperglycemia in early titration. Net effect in Phase 3 was clearly glucose-lowering: in TRIUMPH-2, HbA1c fell 1.4–1.6 points and about 79% of participants on 9 or 12 mg reached an HbA1c of 6.5% or lower, vs 26% on placebo (Lilly-reported, efficacy estimand). | Predictably glucose-lowering across the dose range; no glucagon-component excursions. Longer track record in T2D, approved as Mounjaro since May 2022. |
| Dysesthesia (Phase 3 Signal) | Dose-related dysesthesia (abnormal skin sensation) emerged in Phase 3: 5.1–12.5% vs 0.9% on placebo in TRIUMPH-1, 4.5–7.3% vs 0.7% in TRIUMPH-2, and 8.8% (9 mg) and 20.9% (12 mg) vs 0.7% in TRIUMPH-4 (Lilly toplines). Lilly described events as generally mild to moderate, mostly resolving during treatment and rarely leading to discontinuation. Mechanism not established. | Listed in the Zepbound label but rare: 0.2–0.4% across doses vs 0.1% on placebo in pooled SURMOUNT-1 and SURMOUNT-2 data. |
| Compounding Status | Not a legal 503A compounding product — no FDA-approved reference product, no validated bulk drug substance list entry. Grey-market vendors notwithstanding. | FDA-resolved off the drug-shortage list in 2024; commercial compounding pathway is now narrow/closed. Patient access is through the branded product. |
| Sports / WADA Status | Not named on WADA Prohibited List, but WADA S0 captures unapproved investigational substances. Athletes should treat as prohibited. | Not currently on the WADA Prohibited List, but increasingly scrutinized as performance-relevant in body-composition-sensitive sports. TUE pathway under discussion. |
| Defining Differentiator | The added glucagon receptor — drives extra hepatic fat oxidation, energy expenditure, and among the largest mean weight losses reported in Phase 3 obesity trials (25.0% at 12 mg in TRIUMPH-1). Trade-offs: no completed outcome trial, long-term safety beyond about two years uncharacterized, a dose-related dysesthesia signal, and an extra mechanistic axis to monitor (heart rate, glycemic excursions). | Maturity and breadth of evidence — FDA approval across three obesity-adjacent indications (T2D, weight management, OSA), head-to-head superiority over semaglutide, published maintenance-dose data, growing pleiotropic outcomes in CV, renal, NASH, HFpEF, and psoriasis trials. |
In depth
The same molecule, plus one receptor
Tirzepatide and retatrutide are sister molecules. Both are 39-amino-acid synthetic peptides from Eli Lilly. Both carry a C-20 fatty diacid for albumin binding and weekly dosing. Both activate GIP and GLP-1 receptors centrally to suppress appetite. The defining difference is one extra receptor — retatrutide adds glucagon agonism, which drives hepatic fat oxidation, increases energy expenditure, and produces some of the largest weight-loss numbers reported in obesity pharmacotherapy. That one mechanistic addition is the entire story. In cross-trial comparisons, retatrutide at 12 mg produced 25.0% mean weight loss over 80 weeks in the Phase 3 TRIUMPH-1 trial (NEJM, September 2026), while tirzepatide at 15 mg produced 20.9% over 72 weeks in SURMOUNT-1. Both figures use the treatment-regimen estimand, which counts everyone randomized whether or not they stayed on the drug, so the analysis method is matched. The pattern holds in type 2 diabetes: 18.8% at 12 mg over 80 weeks in TRIUMPH-2 (Lancet, September 2026) versus 14.7% at 15 mg over 72 weeks in SURMOUNT-2. Lilly's headline figures often use the efficacy estimand instead, which assumes everyone stayed on treatment and runs higher (28.3% at 12 mg in TRIUMPH-1; 28.7% in TRIUMPH-4, whose treatment-regimen figure was 23.7%), so those numbers should not be set against SURMOUNT's treatment-regimen results. Even with matched estimands, these are different trials with different durations, populations, and placebo responses (3.9% in TRIUMPH-1 vs 3.1% in SURMOUNT-1). They are not a head-to-head result. The direct comparison, TRIUMPH-5 (NCT06662383), randomizes adults with obesity to retatrutide or tirzepatide and has an estimated primary completion in November 2026. The honest position today is that retatrutide appears to produce roughly 4 percentage points more weight loss than tirzepatide, and the size of that advantage in a true head-to-head trial is unknown until TRIUMPH-5 reports.
Why glucagon matters mechanistically
The argument for adding glucagon-receptor activation to dual GIP/GLP-1 agonism is straightforward: GLP-1 and GIP reduce calorie intake by suppressing appetite, but they don't change the energy-expenditure side of the equation. Glucagon does. Glucagon-receptor activation increases hepatic fat oxidation, elevates resting energy expenditure, and drives thermogenesis. The classical problem with glucagon — its hyperglycemic effect — is offset by the glucose-lowering action of the GLP-1 and GIP components, so the net glycemic effect of the triple agonist is still strongly favorable (HbA1c fell 1.4–1.6 points in Phase 3 TRIUMPH-2 and up to 2.02 points in Phase 2). The 2026 metabolomics substudy (Pearson et al., n=495) provided the first mechanistic decomposition of retatrutide's weight-loss signature in humans. Higher doses drove a coordinated increase in fatty-acid oxidation markers (3-hydroxybutyrate, acetylcarnitine, free carnitine, long-chain acylcarnitines) plus reductions in insulin-resistance markers (branched-chain amino acids, 2-aminoadipic acid, urate). Mediation analysis attributed approximately 23.2% of the weight-reduction effect in non-T2D participants to the acylcarnitine cluster alone — direct human evidence that the glucagon-receptor-driven fatty-acid oxidation pathway is a meaningful contributor to retatrutide's weight loss, not just a pharmacological hypothesis.
Liver fat: where retatrutide's mechanistic story shines hardest
If weight loss is where retatrutide's advantage is real but contested, liver fat is where the mechanistic case is strongest. The Phase 2a MASLD substudy (Sanyal et al., Nature Medicine 2024) reported relative liver-fat reductions of 81–82% at 24 weeks on the 8 and 12 mg doses, with liver fat back in the normal range (below 5%) in 79–86% of those participants. Liver fat was measured by MRI rather than biopsy, so this shows fat clearance rather than proven MASH resolution, and histology-based MASH results are still pending. Tirzepatide's SYNERGY-NASH Phase 2 trial, which used biopsy endpoints, showed meaningful MASH resolution and fibrosis improvement. The two programs used different endpoints, so their liver effects cannot be ranked directly, but retatrutide's direct glucagon-receptor action on the liver is the mechanistic reason to expect a larger liver-fat effect. For patients whose primary cardiometabolic problem is hepatic steatosis or MASH rather than (or in addition to) weight, the retatrutide profile is mechanistically the more aligned one.
Where tirzepatide's mature evidence base is the bigger asset
For most actual prescribing decisions today, the question is not which molecule has the bigger headline number — it's which one has the evidence base, the regulatory approval, and the access pathway. Tirzepatide wins all three by a wide margin. It is FDA-approved for type 2 diabetes (Mounjaro, May 2022), chronic weight management (Zepbound, November 2023), and obstructive sleep apnea in adults with obesity (Zepbound, December 2024). It has a completed head-to-head superiority trial against semaglutide (SURMOUNT-5: 20.2% vs 13.7%). It has a completed cardiovascular outcome trial — SURPASS-CVOT found it non-inferior to dulaglutide on cardiovascular events in people with type 2 diabetes. It has growing pleiotropic data — a 23% reduction in major kidney events in SURPASS-CVOT's exploratory analysis (Lancet Diab Endo 2026), significant improvements in HFpEF symptoms and exercise capacity in a dedicated trial, superior fibrosis improvement in MASH, and a 2026 Phase 3b trial in psoriasis with obesity that quintupled simultaneous skin-clearance and weight-loss rates versus ixekizumab alone. It has SURMOUNT-MAINTAIN (Lancet 2026), the trial that established 5 mg as a viable maintenance dose for preserving weight loss after the maximum tolerated dose. And it has approximately four years of post-marketing real-world safety data that retatrutide will need years more to accumulate. Retatrutide's Phase 3 program has now delivered most of its weight-loss readouts. TRIUMPH-4 (knee osteoarthritis) reported topline results in December 2025, TRANSCEND-T2D-1 was published in the Lancet in June 2026, TRIUMPH-3 (severe obesity with cardiovascular disease) reported topline results in July 2026, and TRIUMPH-1 and TRIUMPH-2 were published in NEJM and the Lancet on 29 September 2026. What it still lacks is outcome data. TRIUMPH-3 recorded fewer major cardiovascular events than anticipated, so its cardiovascular results were inconclusive, and the dedicated cardiovascular and kidney outcomes trial (TRIUMPH-Outcomes, NCT06383390) runs to 2029. The head-to-head trial against tirzepatide (TRIUMPH-5) and the maintenance trial (TRIUMPH-6, NCT06859268) have not reported either.
Safety and tolerability: heart rate and dysesthesia
Both drugs share the class-typical GI profile — nausea, vomiting, diarrhea, and constipation, concentrated at dose-escalation steps and easing on maintenance. Phase 3 put numbers on retatrutide's version. In TRIUMPH-1, nausea affected 29–42% of participants across doses versus 15% on placebo, and discontinuation for adverse events was 4–11% versus 5%; in TRIUMPH-2 it was 4–12% versus 5%. TRIUMPH-4, run only at 9 and 12 mg, saw adverse-event discontinuations of 12–18% versus 4%; Lilly said these tracked with baseline BMI and included people stopping for perceived excessive weight loss, and among participants with a BMI of 35 or higher the rates were 9–12%. Slow titration manages most GI effects. The first difference worth watching is heart rate. Both molecules raise resting heart rate through GLP-1-class effects; retatrutide raised it somewhat more (about +3.5 bpm vs placebo in a 2026 meta-analysis, against about +2 bpm for tirzepatide), while the Zepbound label reports a mean increase of 1–3 bpm for tirzepatide. The glucagon-receptor component is thought to add a small thermogenic and chronotropic effect. This has not produced a clear cardiovascular safety signal so far, but the outcome data needed to rule one out are not in yet. TRIUMPH-2 also recorded more hypotension than placebo (1–6% vs <1%). The second is dysesthesia, an abnormal and often unpleasant skin sensation that emerged as a dose-related signal in Phase 3. It occurred in 5.1–12.5% of retatrutide participants versus 0.9% on placebo in TRIUMPH-1, 4.5–7.3% versus 0.7% in TRIUMPH-2, and 20.9% at 12 mg versus 0.7% in TRIUMPH-4 (Lilly topline figures). Lilly described the events as generally mild to moderate, mostly resolving during treatment and rarely leading to discontinuation, and no mechanism has been established. The Zepbound label lists dysesthesia for tirzepatide too, but at 0.2–0.4% versus 0.1% on placebo. The third, specific to the glucagon component, is the transient HbA1c excursion that can occur in early titration before the GLP-1/GIP glucose-lowering effects fully offset glucagon's hyperglycemic action. It has not translated into poor glycemic control: in TRIUMPH-2, HbA1c fell 1.4–1.6 points versus 0.2 on placebo.
Access
For the patient asking which one they should be on today, the answer is currently structural rather than mechanistic. Tirzepatide is an approved, commercially available drug, sold at US pharmacies as Mounjaro (T2D indication) or Zepbound (obesity / OSA indication). Retatrutide is not FDA-approved. Access is limited to Lilly's clinical trials and, since mid-2026, a US compassionate-use pathway, and it is not legally available through compounding (no approved reference product, no validated bulk drug substance entry). Grey-market and research-chemical vendors advertise retatrutide, but those products carry unresolved regulatory and quality concerns; a 2026 case report described online-sourced retatrutide complicating impending diabetic ketoacidosis in a person with type 1 diabetes. Patients doing well on tirzepatide today are not giving up a future option by staying on it. If retatrutide is approved, whether to switch will be a clinical decision made at that point, informed by TRIUMPH-5's head-to-head data.
How to choose
If you're choosing today: tirzepatide is the answer for essentially everyone, because retatrutide isn't approved and is available only through trials or limited compassionate use. If you're choosing once retatrutide is approved: the calculus shifts to which mechanism aligns with the dominant clinical problem. For weight loss alone, retatrutide's cross-trial advantage of roughly 4 percentage points is real but modest at the population level, and TRIUMPH-5 will show how much of it holds up head to head. For weight loss plus hepatic steatosis, retatrutide's glucagon-driven liver-fat effect is the larger mechanistic advantage, though histology-based MASH data are still pending. For weight loss plus established type 2 diabetes, both are highly effective; tirzepatide has the longer track record and the cleaner glycemic profile, while retatrutide produced more weight loss in TRIUMPH-2 than tirzepatide did in SURMOUNT-2 (18.8% vs 14.7%, cross-trial). For weight loss plus OSA, tirzepatide is the labeled choice; retatrutide's TRIUMPH-1 substudy showed large apnea-hypopnea reductions, but it has no OSA indication. For patients with significant pre-existing tachycardia or atrial fibrillation, tirzepatide's smaller heart-rate footprint may be preferable.
Bottom line
In cross-trial data, retatrutide is the more potent molecule on weight loss and liver fat. Tirzepatide is the mature molecule on regulatory approval, outcome-trial evidence, real-world evidence, pleiotropic indications, and maintenance-dose data. Today the choice is forced — tirzepatide is the only one that exists in the pharmacy. Once retatrutide is approved (Lilly plans to submit in Q1 2027, so approval is 2027 at the earliest), the choice will turn on whether the extra mechanistic firepower of glucagon-receptor agonism matches the patient's dominant cardiometabolic problem, whether the extra heart-rate effect and the dysesthesia signal are acceptable, and whether the depth of long-term safety data justifies waiting for the post-marketing record to mature. For the average patient with obesity alone, tirzepatide is likely to remain the default for some time after approval; retatrutide will be the consequential choice in the subset where weight-loss magnitude or hepatic-fat reduction is the dominant clinical priority.
These peptides are often used together. See our stack profiles for combination details.