This is genuinely one of the harder clinical decisions in pediatric endocrinology right now, and the fact that you're thinking about it carefully speaks well of you as a parent.
Let me lay out the evidence as objectively as I can:
The STEP TEENS trial (published in NEJM, 2022) randomized 201 adolescents aged 12-17 with obesity to semaglutide 2.4mg vs placebo for 68 weeks.[1] Key results:
- BMI reduction: -16.1% with semaglutide vs +0.6% with placebo
- Body weight reduction: -14.7% vs +2.8%
- Improvements in cardiometabolic risk factors (waist circumference, lipids, HbA1c)
- Safety profile was broadly consistent with the adult trials
- GI side effects were the most common (nausea ~40%, vomiting ~27%)
The 2-year extension data presented at ENDO 2024 showed sustained benefits with continued treatment. Importantly, linear growth (height) was NOT impacted — this was a key concern going in.
What we DON'T know: long-term effects beyond 2 years in adolescents, impact on puberty timing (no signal so far but limited data), effects on bone mineral density during peak bone accrual years, and whether early use alters the trajectory of adult obesity.
The AAP released updated clinical practice guidelines in 2023 recommending pharmacotherapy for adolescents with severe obesity (BMI ≥120% of the 95th percentile), which your son likely meets at his current stats.[2]
My personal take: at a BMI of ~38 at age 15 with documented failure of behavioral interventions, the metabolic risk of untreated obesity is substantial and well-documented. The risk-benefit calculation favors treatment in most cases.
[2] Hampl SE, et al. "Clinical Practice Guideline for the Evaluation and Treatment of Children and Adolescents With Obesity." Pediatrics. 2023;151(2):e2022060640.