Tirzepatide vs semaglutide: the head-to-head result and what each costs
One trial put the two molecules against each other in people with obesity and no diabetes. Tirzepatide took off 20.2 percent of body weight at 72 weeks and semaglutide 13.7 percent.
Tirzepatide beat semaglutide in the one trial that put them head to head, SURMOUNT-5. Eli Lilly, which makes tirzepatide, funded it. Both drugs took weight off.
What the head-to-head trial found
SURMOUNT-5 randomly assigned 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. It was open-label, so everyone knew which drug they were on.
| At 72 weeks | Tirzepatide | Semaglutide |
|---|---|---|
| Mean weight change | -20.2% | -13.7% |
| Mean waist change | -18.4 cm | -13.0 cm |
| Most common adverse events | Gastrointestinal in both groups, mostly mild to moderate, mostly during dose escalation | |
An average is not a forecast. Participants in both groups ranged from large losses to almost none, and the trial does not tell you which group you would have been in.
Which name is which
Tirzepatide is sold as Zepbound for weight and Mounjaro for type 2 diabetes. Semaglutide is sold as Wegovy for weight, Ozempic for diabetes and Rybelsus as a daily tablet. Compounded versions of both molecules are made by licensed US pharmacies against a prescription. The FDA does not review compounded products for safety, effectiveness or quality, and they are not the approved medication.
The mechanisms differ. Semaglutide acts on the GLP-1 receptor. Tirzepatide acts on the GLP-1 receptor and the GIP receptor. SURMOUNT-5 did not test which receptor produced the gap. The dose ladders differ too, and both are on our dosing pages: Zepbound, Wegovy, Mounjaro and Ozempic.
What each one costs
Across the 27 programs on our chart the cheapest all-in cash route is $149 a month at Strut Health, checked August 31, 2026, and prices run to $448. Filter the chart by molecule and the two price ranges barely overlap.
Every price we track, free to cite, updated every Monday.
Questions people ask
Is tirzepatide always better than semaglutide?
No. SURMOUNT-5 reports a group average, not a rule for one person. It also tested only the two highest tirzepatide doses against the two highest semaglutide doses in people with obesity and no diabetes, so it says nothing about lower doses, about people with diabetes, or about how either drug suits your own history. Side effects and tolerability decided who stayed on treatment as much as the numbers did.
Which one is cheaper?
Neither molecule has a fixed price. What sets your bill is the route: branded through insurance, branded cash through the maker, or compounded through a telehealth program. Filter the chart by molecule and each route carries the price the program publishes.
Can I switch from one to the other?
People do, usually for cost or for side effects. The doses do not translate across molecules, so a switch means a new ladder rather than the same number on a different pen. Our switching guide covers the gap between programs, and the dose question belongs with your prescriber.
Do compounded versions perform the same?
There is no trial that answers that. SURMOUNT-5 tested the approved products. A compounded product is made by a pharmacy against a prescription, the FDA does not review it for safety, effectiveness or quality, and the formulation can differ from the approved medicine. Confirm the active ingredient and the pharmacy with the prescriber.
Sources
Evidence checked August 31, 2026
Every figure above is taken from the document beside it, the FDA label or the trial that produced it, so you can read the source instead of trusting us. No clinician reviews these pages. What that means.
- The head-to-head weight and waist results at 72 weeks, the trial design, the enrollment and the funderSURMOUNT-5: tirzepatide as compared with semaglutide for the treatment of obesity (NEJM, 2025)
- The earlier head-to-head of the same two molecules in type 2 diabetesSURPASS-2: tirzepatide versus semaglutide once weekly in patients with type 2 diabetes (NEJM, 2021)
- Semaglutide's own registration result in adults with overweight or obesitySTEP 1: once-weekly semaglutide in adults with overweight or obesity (NEJM, 2021)
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