Semaglutide vs Tirzepatide

Semaglutide is a glucagon-like peptide-1 receptor agonist, which is how its own FDA label describes it. Tirzepatide is labeled as a glucose-dependent insulinotropic polypeptide receptor and glucagon-like peptide-1 receptor agonist, so it works at two incretin receptors rather than one. Beyond that, the two behave alike in the ways you notice: once weekly, injected under the skin of the abdomen, thigh or upper arm, escalated slowly, and prescribed alongside a reduced-calorie diet and more physical activity rather than instead of them. The pharmacology diverges at exactly one receptor.

The tidy story is that the second receptor buys the extra weight loss. The literature is not that tidy. A 2026 review in Appetite sets out the paradox directly: both activation and blockade of the GIP receptor reduce body weight and improve the results of GLP-1 based therapy, which means the two opposite pharmacologic strategies converge on the same outcome by different biology. The same argument runs in the journal Diabetes, where 2025 papers make the case for GIP receptor agonism in obesity and for GIP receptor antagonism. Read the mechanism as the best current hypothesis for the difference rather than an established cause of it.

One trial has compared these two head to head. SURMOUNT-5 randomized 751 adults with obesity and without type 2 diabetes to the maximum tolerated dose of tirzepatide, 10 mg or 15 mg, or the maximum tolerated dose of semaglutide, 1.7 mg or 2.4 mg, once weekly for 72 weeks; the least-squares mean change in weight was -20.2% with tirzepatide and -13.7% with semaglutide, and waist circumference fell 18.4 cm against 13.0 cm. Those are group averages across 72 weeks, and individual results vary widely around an average of that kind.

Two design facts belong next to that number rather than in a footnote. SURMOUNT-5 was an open-label trial, so participants and investigators both knew which drug had been assigned, which can move self-reported outcomes and escalation decisions. And the semaglutide arm ran at a maximum tolerated 1.7 mg or 2.4 mg, matching how the drug is labeled but leaving this a comparison of tolerated regimens rather than of matched doses. The finding is real and it is the only direct one available. It answers which regimen produced more weight loss. Which receptor produced it is a separate question.

Four brand names sit across these two molecules and the approved uses are not interchangeable. Wegovy, a semaglutide injection, is indicated to reduce excess body weight and maintain weight reduction long term in adults with obesity or with overweight plus a weight-related condition, and to reduce the risk of major adverse cardiovascular events in adults with established cardiovascular disease and obesity or overweight. Ozempic, also a semaglutide injection, is indicated for glycemic control in type 2 diabetes, for cardiovascular risk reduction in type 2 diabetes with established cardiovascular disease, and to reduce the risk of sustained eGFR decline and end-stage kidney disease.

The tirzepatide pair splits the same way. Zepbound is indicated for weight reduction and long-term maintenance, and separately to treat moderate to severe obstructive sleep apnea in adults with obesity, while Mounjaro is indicated as an adjunct to diet and exercise for glycemic control in adults and in children aged 10 and older with type 2 diabetes. If obstructive sleep apnea is part of your picture, only one of these four products is labeled for it, and that is a genuine point of difference rather than a marketing one.

This is where coverage decisions actually get made. A plan that excludes weight-loss drugs is reading the indication on the label, never the ingredient inside the pen, so the pair approved for diabetes and the pair approved for weight are treated as different benefits even when the chemistry behind them overlaps. Which of the four is right for you is a prescribing decision, and none of this is medical advice. Before you compare efficacy at all, find out which of the four your plan will consider and on what documentation.

SELECT was a placebo-controlled superiority trial in 17,604 adults aged 45 and over with preexisting cardiovascular disease and a body-mass index of 27 or greater but no diabetes; a first cardiovascular death, nonfatal myocardial infarction or nonfatal stroke occurred in 6.5% on semaglutide 2.4 mg against 8.0% on placebo, a hazard ratio of 0.80 with a 95% confidence interval of 0.72 to 0.90 over a mean 39.8 months. That result is why a cardiovascular risk-reduction indication appears on the Wegovy label. SURPASS-CVOT asked a different question. It randomized 13,299 adults with type 2 diabetes and atherosclerotic cardiovascular disease to tirzepatide or to dulaglutide, an active comparator already shown to reduce cardiovascular events, and tested for noninferiority; the composite endpoint occurred in 12.2% on tirzepatide and 13.1% on dulaglutide, a hazard ratio of 0.92 with a 95.3% confidence interval of 0.83 to 1.01, meeting noninferiority at P=0.003 and missing superiority at P=0.09.

So one molecule has beaten placebo for cardiovascular events in obesity without diabetes, and the other has matched an active drug in type 2 diabetes. Different populations, different comparators, different questions. Equating the two results would be wrong.

Wegovy starts at 0.25 mg once weekly for four weeks, moves to 0.5 mg through week 8, 1 mg through week 12 and 1.7 mg through week 16, with a maintenance dose of either 2.4 mg or 1.7 mg from week 17 onward, and the label tells prescribers to consider delaying escalation by four weeks if a dose is not tolerated. Zepbound starts at 2.5 mg once weekly for four weeks, moves to 5 mg, then rises in 2.5 mg increments after at least four weeks at each dose, with maintenance at 5, 10 or 15 mg and a 15 mg ceiling.

Lay those schedules side by side and a practical difference shows up that no efficacy percentage captures. Sixteen weeks of escalation gets you to a semaglutide maintenance dose. Reaching the 15 mg tirzepatide ceiling takes at least twenty weeks, because every 2.5 mg step needs its own four weeks. Both labels also permit stopping at a lower maintenance dose, and Zepbound explicitly allows a lower maintenance dose if a higher one is not tolerated. If you settle below the top dose, you are no longer on the regimen the head-to-head trial measured.

In the Wegovy trials, 6.8% of adults on 2.4 mg permanently discontinued because of adverse reactions against 3.2% on placebo, with nausea, vomiting and diarrhea the most common reasons, and 4.3% stopped specifically for gastrointestinal reactions against 0.7% on placebo. In the Zepbound trials, 4.8%, 6.3% and 6.7% discontinued at 5 mg, 10 mg and 15 mg against 3.4% on placebo, gastrointestinal reactions were reported by 56% at every dose against 30% on placebo, and most of those who stopped did so in the first few months.

Now the part most comparisons get wrong, and it is worth being blunt about. Those two percentages were generated in different trial programs, with different participants, different placebo arms and different reporting rules. Lining them up and subtracting produces a number that means nothing at all. The same objection applies to weight-loss percentages quoted from separate STEP and SURMOUNT trials. Within SURMOUNT-5, where both drugs ran under one protocol, the most common adverse events in both groups were gastrointestinal, mostly mild to moderate, and occurred primarily during dose escalation. That is the only tolerability comparison on this page you can read directly.

An online visit for either molecule runs the same shape. You supply height, weight and a weight-related medical history, then a licensed clinician decides whether a prescription is appropriate at all. Two screening questions carry more weight than the rest. Wegovy is contraindicated with a personal or family history of medullary thyroid carcinoma or with Multiple Endocrine Neoplasia syndrome type 2, and with prior serious hypersensitivity to semaglutide, and Zepbound carries the identical contraindications for tirzepatide. Both labels also carry a boxed warning about thyroid C-cell tumors seen in rodents.

The logistics differ more than the medicine does. These are cold-chain products: an unopened Zepbound KwikPen is refrigerated at 2 to 8 degrees Celsius and discarded after 30 days if it has been kept at room temperature, or after four weekly doses once it is in use. That has practical consequences for delivery timing, for travel and for what happens when a shipment is delayed. Ask any service how it handles a missed delivery window before you sign up, because a gap in supply during escalation usually means restarting at a lower dose.

In the STEP 1 trial extension, 327 participants who had lost a mean 17.3% on semaglutide 2.4 mg over 68 weeks regained 11.6 percentage points in the year after both the drug and the lifestyle program stopped, leaving a net 5.6% loss at week 120, with most cardiometabolic improvements drifting back toward baseline. That is roughly two thirds of the loss returning, and the authors concluded that ongoing treatment is required to maintain the improvements.

SURMOUNT-4 tested the same question by randomized withdrawal: after a 36-week open-label tirzepatide lead-in that produced a mean 20.9% reduction, 670 participants either continued tirzepatide or switched to placebo for 52 weeks, and weight then changed by -5.5% on continued tirzepatide against +14.0% on placebo. Neither trial is a criticism of either drug. Together they reframe the decision: the number that matters is not which drug wins at week 72, but what your maintenance plan and your coverage look like in year two and beyond.

CMS publishes the National Average Drug Acquisition Cost, a survey of what retail pharmacies pay for each national drug code. On the 17 June 2026 file, Wegovy 2.4 mg per 0.75 mL was $435.33 per mL, which works out to about $326 for one weekly dose and roughly $1,306 for four. Zepbound was $525.72 per mL in the 15 mg single-dose pen, about $263 a dose, while the same 15 mg dose in the multi-dose KwikPen was $280.75 per mL across 2.4 mL, about $168 a dose and roughly $674 for four. Same drug, same strength, a third less per dose in the multi-dose presentation.

Two things that figure is not. It is not retail and it is not your price, because what you pay turns on coverage, manufacturer self-pay programs and which pharmacy fills it. It is also not evidence that a cheaper generic exists: every semaglutide and tirzepatide code in that file is classified as a brand product. For reference, the same source lists Mounjaro at $538.48 per mL on 19 August 2026 and Ozempic at $331.94 per mL on 22 July 2026.

We publish no single monthly price for either molecule, because there is not one honest number to publish.

Most of what separates one telehealth service from another here is logistical rather than clinical. Start by asking which of the four approved products it can prescribe and dispense, because a service routed to one manufacturer is not offering you this comparison at all. Then ask what the quoted monthly figure covers at 2.4 mg or 15 mg rather than at the starting dose, since escalation changes the pen, and on the tirzepatide side it can change the presentation and the price with it.

After that, ask the maintenance questions, which is where the withdrawal trials above should push you. Who reviews your response and how often, what happens if you stop tolerating a dose, whether the service submits prior authorization for you and what documentation it needs from you to do it, and whether care continues past twelve months. Whether either molecule is appropriate for you, and at what dose, is a prescribing decision made with a licensed clinician. Nothing on this page is medical advice or a recommendation to take either drug.