A direct randomized comparison
SURMOUNT-5 was a 72-week, open-label, randomized phase 3b trial involving 751 adults with obesity and without type 2 diabetes. It compared the maximum tolerated weekly injected tirzepatide dose of 10 or 15 mg with semaglutide at 1.7 or 2.4 mg. Eli Lilly funded the study.[source]
Open-label means the assigned treatment was known rather than masked. Both groups received diet and activity counseling. Randomization makes this more informative for the studied comparison than placing unrelated trial averages beside each other.[source]
The main result in ordinary units
At week 72, the reported mean body-weight change was −20.2% for tirzepatide and −13.7% for semaglutide. The difference is 6.5 percentage points. These results use the treatment-regimen estimand, rather than representing a guaranteed outcome for every person who remained on treatment.[source][source]
The 95% confidence intervals were −21.4% to −19.1% and −14.9% to −12.6%, respectively. Those intervals describe uncertainty around the group estimates; they are not the range in which every individual’s response will fall.[source]
The trial does not establish a universal safety winner
Gastrointestinal events were the most common adverse events in both groups, generally mild or moderate and often occurring during escalation. The sponsor reported treatment discontinuation due to adverse events in 6.1% of the tirzepatide group and 8.0% of the semaglutide group.[source]
The sponsor explicitly notes that the study was not powered to compare safety and tolerability. Those descriptive rates should not be converted into a claim that one drug is always safer.
What was not compared
The trial did not study current oral Wegovy, the newer 7.2 mg Wegovy HD regimen, compounded preparations or competing telehealth providers. Current Wegovy labeling includes formulations beyond the comparator used here.[source]
It also does not settle treatment choice for a person with diabetes, a different medical history or a different clinical goal. A direct result is strong evidence for its actual question, not every neighboring question.
Use the result as one part of the consultation
Discuss the finding alongside the current label, relevant health conditions, tolerability, access and ability to continue care. Do not turn the group average into a personal forecast or a reason to switch treatment without a prescriber.
Our provider comparison evaluates the access model. CoreAge Rx’s commercial first position is unrelated to this trial and does not imply that its compounded products produced these results.
Sources & further reading
Provider pages establish what a brand markets. Clinical and regulatory sources establish the limits of the evidence. Each source has its own last-checked date below.
- Aronne et al., NEJM 2025: tirzepatide compared with semaglutide for obesityPrimary randomized trial abstract; SURMOUNT-5, 751 adults without diabetes, 72 weeks; funded by Eli Lilly · Checked October 8, 2026
- Lilly: complete SURMOUNT-5 results and trial designTrial sponsor report; treatment-regimen estimand and safety-comparison limitations · Checked October 8, 2026
- Wegovy prescribing informationManufacturer labeling; formulation-specific directions and safety information · Checked October 8, 2026