Tirzepatide vs Semaglutide: Head-to-Head Trial Evidence

Searches for “Mounjaro vs Ozempic” often combine two different questions: glucose control in type 2 diabetes and weight management in people without diabetes. Two head-to-head trials help answer those questions, but their results should not be mixed into a single universal ranking.

This page explains the evidence. For device, coverage and appointment questions, see our practical Mounjaro and Ozempic comparison.

SURPASS-2: adults with type 2 diabetes

SURPASS-2 randomly assigned 1,879 adults with type 2 diabetes in an open-label, 40-week trial. It compared tirzepatide 5, 10 or 15 mg weekly with semaglutide 1 mg weekly. Average HbA1c fell by 2.01, 2.24 and 2.30 percentage points in the tirzepatide groups, versus 1.86 with semaglutide. Average weight losses were 7.6, 9.3 and 11.2 kg, versus 5.7 kg. Frías et al., 2021

The population had diabetes, and the comparator was semaglutide 1 mg. This study does not directly answer how tirzepatide compares with semaglutide 2.4 mg in adults without diabetes. That distinction matters when a headline describes the trial simply as “Mounjaro beats Ozempic.”

SURMOUNT-5: adults with obesity without diabetes

SURMOUNT-5 randomly assigned 751 adults with obesity without type 2 diabetes. It was open-label and lasted 72 weeks, comparing maximum tolerated tirzepatide doses of 10 or 15 mg with semaglutide 1.7 or 2.4 mg. Average weight change was −20.2% versus −13.7%, a difference of 6.5 percentage points. Gastrointestinal events were the most common adverse events in both groups, usually mild to moderate and occurring during dose escalation. Eli Lilly funded the trial. Aronne et al., 2025

That result supports a greater average weight reduction with tirzepatide under this trial's conditions. It is not a promise that an individual will lose that amount, tolerate the tested dose or have access to either regimen. This comparison concerns obesity-treatment doses, not a direct comparison of every Mounjaro and Ozempic prescription.

Read the result in five steps

1. Check who enrolled. A study in people with diabetes may answer a different question from one excluding diabetes.
2. Check the dose. Comparing ingredient names alone leaves out part of the intervention.
3. Check the outcome and time. HbA1c, kilograms and percentage weight change are different measures; 40 and 72 weeks are different follow-up periods.
4. Check the distribution. An average compresses different individual responses into one number. It is not a personal target.
5. Check the practical fit. A trial cannot tell you your insurance coverage, preferred device or individual tolerability.

This reading checklist is our editorial framework for interpreting a comparison, rather than a treatment recommendation.

What the trials do not settle

These trials do not establish that one option is best for every person or every treatment goal. Their open-label designs meant participants and investigators knew treatment assignments. That is a feature to consider when interpreting the results, alongside the randomized design and prespecified outcomes.

Avoid using an obesity trial to claim an approved indication for a differently named product. For current product indications and safety information, consult the prescribing information and your clinician. Our tirzepatide overview links the relevant manufacturer documents.

Evidence checked September 9, 2026. This explainer preserves the difference between trial results and an individual prescribing decision; it does not supply a dose conversion or switching plan.