Semaglutide or tirzepatide? Start with what matters to you.
The larger weight-loss number is worth knowing. It is only part of the choice.
First, untangle the names
Semaglutide is the ingredient in FDA-approved medicines including Wegovy, Ozempic and Rybelsus. Tirzepatide is the ingredient in Zepbound and Mounjaro. A compounded preparation is a separate product and is not FDA-approved.
Semaglutide activates a hormone target called the GLP-1 receptor, involved in appetite and blood sugar. Tirzepatide activates that target and the receptor for GIP, another gut hormone, as the Zepbound (tirzepatide) label explains. The extra target doesn't decide which medicine fits a person.
What the weight comparison found
The SURMOUNT-5 trial studied adults with obesity without type 2 diabetes. By week 72, participants assigned tirzepatide had lost 20.2% of body weight on average; those assigned semaglutide averaged a 13.7% loss. Participants received the highest study doses they could tolerate.
Eli Lilly, the maker of tirzepatide, funded the trial. It was open-label, meaning participants and researchers knew which medicine was assigned. This is a useful direct comparison, rather than two unrelated study headlines placed together.
The result describes averages, not what every participant experienced. It leaves room for a practical question: does this study address your reason for considering treatment?
The comparison tested manufactured medicines, not compounded preparations. Its percentages do not establish what a compounded version will do. The product distinction matters alongside the study population.
Three studies, three questions
A weight result cannot stand in for every other benefit.
| Study | People & time | Finding | What it can answer |
|---|---|---|---|
| SURMOUNT-5 | Obesity without type 2 diabetes. | Greater average weight loss with tirzepatide at 72 weeks. | A direct weight comparison; the sponsor and open-label design are described above. |
| SURPASS-2 | Type 2 diabetes. | Greater blood-sugar and weight reductions with tirzepatide. | In this trial, participants in the semaglutide group received 1 mg weekly. |
| SELECT | Aged 45 or older; established heart or blood-vessel disease; body mass index (BMI) at least 27; no diabetes. | Lower combined risk of death from heart or blood-vessel disease, nonfatal heart attack or nonfatal stroke with semaglutide. | Against placebo; no tirzepatide group. |
Read the weight, diabetes and heart-outcome findings with their different groups in mind.
Why the diabetes result needs its own space
The diabetes comparison measured HbA1c, a marker of blood sugar over several months, as well as weight. The semaglutide amount studied was lower than the highest diabetes strength now approved. That limits how broadly we can use its result.
It doesn't settle every comparison between the two medicines. More detail belongs beside a result when it could change the meaning.
Leave room for the safety questions
The Wegovy (semaglutide) and Zepbound (tirzepatide) labels warn about digestive problems and more serious risks. Both carry a boxed warning about tumors in thyroid C cells, a particular type of thyroid cell, seen in rodents. Whether these medicines cause those tumors in humans is unknown. Our effects page explains the semaglutide cautions.
The Zepbound label has a specific warning about hormonal birth-control pills. It instructs prescribers to advise a non-oral method or added barrier protection for four weeks after starting and after each dose increase. That's label information to discuss with the prescriber.
A useful comparison ends with your circumstances back in the picture. What is treatment meant to change, which warnings matter to your history, and who will review how it's going?