Lilly starts phase 3 tirzepatide weight trial in teenagers
A 160-person Lilly study will test whether tirzepatide changes BMI in adolescents aged 12 to 17, an age group where the drug's weight effects have not been established [1].
Eli Lilly has started a phase 3 trial of tirzepatide in teenagers with obesity — the first tirzepatide weight trial in that age group. The study, called SURMOUNT-ADOLESCENTS and registered as NCT06075667, plans to enroll 160 participants aged 12 to 17 [1].
Tirzepatide is the molecule in the diabetes drug Mounjaro and the weight drug Zepbound [1]. To join SURMOUNT-ADOLESCENTS, a teenager must be 12 to 17 years old and have obesity, or have overweight plus at least one weight-related health condition [1]. The record lists 160 as the estimated enrollment, so the final number of teenagers who take part may differ [1].
The main measure is percent change in body mass index at week 72 [1]. BMI is a ratio of weight to height, and percent change in BMI is a common way to compare weight trials; it is not the same as a change in pounds. Participants also have the option to continue into an extension that runs 156 more weeks [1].
The registry lists primary completion — when the last participant is expected to finish the main phase — as June 2, 2026 [1]. No results have been posted [1]. The record does not say whether the trial is placebo-controlled, what doses are being tested, how often the drug is given, or how many participants have enrolled so far. Those details have not been disclosed [1].
This weight study is separate from any pediatric testing of tirzepatide for type 2 diabetes; the record for NCT06075667 covers the weight trial only [1].
Why it matters for patients
For parents and teenagers weighing treatment options, evidence from adults often does not answer what happens in a growing adolescent. This trial is built to measure that in teenagers, but it will not produce answers until the main phase finishes, and nothing has been reported yet [1].
That leaves the central questions open: whether tirzepatide lowers BMI in 12- to 17-year-olds, how large any change is, and what side effects teenagers experience. None of that has been reported [1].
It is also worth separating trial results from prescribing. Participation happens under a study protocol with specific age and weight criteria, not a standard prescription [1]. The study record does not address whether Lilly plans to seek approval of tirzepatide for adolescents, and no timeline for that has been disclosed [1].
What happens next
The main phase carries a listed primary completion date of June 2, 2026 [1]. Some participants may continue in the optional 156-week extension past that point [1]. Results are typically posted to the registry after a trial's main phase ends, but the record gives no date for posting results, and none have been posted [1].
Until those results appear, whether tirzepatide helps teenagers with obesity — and how it compares with other options in that age group — is not known [1].
Sources
Semaglutides.org provides information only, not medical advice. Talk to a licensed provider about your own care before making changes. Some telehealth links are affiliate links and are labeled where they appear.