GLP-1 Medicines for Teenagers: What STEP TEENS and the Adolescent Trials Show About Weight, Doses and Side Effects

Do GLP-1 medicines work for teenagers? In randomized trials, yes, and by a wide margin. In STEP TEENS, adolescents with obesity on weekly semaglutide cut their BMI by 16.1% over 68 weeks while the placebo group's BMI edged up. The same trials also show more stomach side effects, more gallstones than adults get, and weight that returns when the drug stops.

Parents ask about this more and more, often because they or another adult in the house already take one of these drugs. The adult evidence does not transfer neatly. Teenagers are still growing, their BMI is judged against age and sex percentiles, and the trials in this age group are smaller and shorter than the adult ones.

This article covers the three main adolescent trials (semaglutide, liraglutide and tirzepatide), what the label now says about dosing, including the lower 1.7 mg teen maintenance option, the side effects that differ from adults, and the questions that remain open.

Which GLP-1 medicines can teenagers take?

What the label and the trials cover

Semaglutide injection (Wegovy) is labeled for weight reduction in pediatric patients aged 12 years and older with obesity. The current prescribing information on DailyMed, revised in June 2026, lists that use alongside the adult indications, and it pairs the drug with a reduced-calorie diet and increased physical activity rather than presenting it as a stand-alone treatment.

Liraglutide 3.0 mg (Saxenda), a daily GLP-1 injection, is the other labeled option. Its prescribing information, revised in February 2026, covers pediatric patients aged 12 years and older with obesity and a body weight greater than 60 kg. Its pivotal adolescent trial was published by Kelly and colleagues in the New England Journal of Medicine in 2020. Tirzepatide has been tested in youth, but in a different group: SURPASS-PEDS enrolled 10 to under 18 year olds with type 2 diabetes, so its results speak to blood sugar control first and weight second.

Labels are not the only reference point. A 2026 network meta-analysis in JAMA Pediatrics pooled 42 randomized trials with 3835 participants aged 10 to 19 and found that every medicine worked better when combined with structured lifestyle treatment than when used alone. Lifestyle treatment on its own also lowered BMI, by 3.85 points against control.

What did the STEP TEENS trial find?

Weghuber and colleagues, New England Journal of Medicine, 2022

STEP TEENS found that weekly semaglutide 2.4 mg lowered BMI by 16.1% in adolescents with obesity, while BMI on placebo rose by 0.6%. The estimated difference was 16.7 percentage points. The trial randomized 201 participants aged 12 to under 18, two to semaglutide for every one on placebo, and both groups received lifestyle counseling for 68 weeks. 180 of them (90%) completed treatment.

Most teenagers in the semaglutide group reached a clinically meaningful threshold. 95 of 131 (73%) lost at least 5% of their body weight, against 11 of 62 (18%) on placebo. Waist size, HbA1c, most blood lipids and the liver enzyme ALT also improved more with semaglutide than with placebo.

The result was larger than in the liraglutide trial and in the same range as adult semaglutide trials. One caveat is built into the design: everyone, including the placebo group, was receiving lifestyle support, so the numbers show what the drug added on top of counseling.

How many teenagers moved out of the obesity range?

Kelly and colleagues, Obesity, 2023

Close to half did. A post hoc analysis of STEP TEENS found that 44.9% of semaglutide-treated participants ended week 68 in the normal-weight or overweight BMI category, compared with 12.1% on placebo. Because teen BMI categories are set by age and sex percentiles, this is a more intuitive way to read the result than a raw percentage change.

The shift was largest at the severe end. The share of semaglutide-treated participants in class III obesity, the highest category, fell from 37.3% to 13.6%, while it rose in the placebo group. Overall, 73.7% of the semaglutide group improved by at least one BMI category, against 19.0% on placebo.

How did liraglutide compare in adolescents?

Kelly and colleagues, New England Journal of Medicine, 2020

Liraglutide worked, though less strongly than semaglutide did later. The trial randomized 125 adolescents to daily liraglutide 3.0 mg and 126 to placebo, all with lifestyle therapy, for 56 weeks. Liraglutide lowered BMI by 4.64 percentage points more than placebo, and body weight by 4.50 kg more, or 5.01 percentage points.

43.3% on liraglutide reached at least a 5% BMI reduction, against 18.7% on placebo, and 26.1% versus 8.1% reached at least 10%. Adverse events led 10.4% of the liraglutide group to stop treatment, against none on placebo.

The trial also measured what happened next. During a 26-week follow-up after the drug stopped, BMI standard-deviation score rose more in the former liraglutide group than in the placebo group, an estimated difference of 0.15. That pattern of rebound is the same one seen in adults, covered in our article on maintenance after GLP-1 weight loss.

Has tirzepatide been tested in teenagers?

SURPASS-PEDS, Hannon and colleagues, The Lancet, 2025

Tirzepatide has been tested in youth with type 2 diabetes, not in teenagers with obesity alone. SURPASS-PEDS randomized 99 participants aged 10 to under 18, with a mean age of 14.7, to tirzepatide 5 mg, 10 mg or placebo for 30 weeks. All had diabetes that metformin, basal insulin or both had not controlled.

HbA1c fell by 2.23% on pooled tirzepatide and rose by 0.05% on placebo. BMI dropped by 7.4% on 5 mg and 11.2% on 10 mg, against 0.4% on placebo, and the glucose effect held up to 52 weeks. Gastrointestinal effects were the most common side effects, all mild to moderate, and 2 participants (6%) on 5 mg stopped because of an adverse event. These are early numbers in a small group with a different condition, and they say nothing yet about tirzepatide for obesity in otherwise healthy teenagers.

Does semaglutide improve insulin resistance in teenagers?

Arslanian and colleagues, Diabetes Care, 2026

In STEP TEENS it did. A 2026 secondary analysis of 193 participants without type 2 diabetes found that fasting insulin fell by 33.6% on semaglutide versus 10.1% on placebo, and HOMA-IR, a standard estimate of insulin resistance, fell by 35.0% versus 5.3%. ALT, a marker of liver fat and inflammation, dropped by 17.9% versus 3.3%.

Triglycerides, LDL cholesterol, total cholesterol and waist-to-height ratio also improved more on semaglutide. Teenagers who lost at least 20% of their BMI saw larger gains than those who lost less, which suggests that much of the metabolic benefit tracks the weight loss itself. The adult side of this story is in our article on GLP-1 and insulin sensitivity.

What side effects do teenagers get on GLP-1 medicines?

Stomach symptoms, gallstones and the label warnings

Nausea, vomiting and other gut symptoms are the most common side effects in teenagers, as in adults. In STEP TEENS, gastrointestinal adverse events affected 62% of the semaglutide group and 42% on placebo. In the liraglutide trial the figures were 64.8% and 36.5%. Serious adverse events in STEP TEENS were 11% on semaglutide and 9% on placebo.

Gallstones stand out. Five teenagers (4%) on semaglutide in STEP TEENS developed cholelithiasis, and none on placebo. The Wegovy label puts the pediatric rate at 3.8% versus 0%, with cholecystitis at 0.8%, compared with 1.6% versus 0.7% for gallstones in adult weight-loss trials. The label also notes more low blood pressure, rash and hives in pediatric patients than in adults. Rapid weight loss is a known gallstone trigger, explained in our article on GLP-1 medicines and gallstones.

The label's boxed warning applies to teenagers too: semaglutide caused thyroid C-cell tumors in rodents, and whether it does so in humans has not been determined. In the liraglutide trial, one participant died by suicide, which the investigator judged unlikely to be related to treatment.

Do GLP-1 medicines affect mood in teenagers?

Liu and colleagues, Diabetes, Obesity and Metabolism, 2026

The largest study so far did not find higher psychiatric risk. Using electronic health records, the researchers matched 9222 adolescents who started semaglutide, liraglutide or tirzepatide with 9222 on lifestyle treatment and followed them from 30 to 1095 days. Suicide-related events were less common on the medicines, a hazard ratio of 0.74, and so was suicidal ideation, at 0.73.

The authors asked for caution. An observational design cannot rule out that healthier teenagers were more likely to be prescribed a drug, and against metformin as the comparator there was no significant difference. No difference was found for depression, insomnia or eating disorders. Our article on GLP-1 medicines and suicidal thoughts covers the adult regulatory reviews.

Is there a lower dose of semaglutide for teenagers?

The 1.7 mg maintenance option

Yes. The Wegovy label gives a pediatric maintenance dose of 2.4 mg once weekly (recommended) or 1.7 mg once weekly, and tells prescribers to weigh response and tolerability when choosing. Treatment starts at 0.25 mg for 4 weeks and steps up through 0.5 mg, 1 mg and 1.7 mg, with the maintenance dose from week 17 onward.

The 1.7 mg option did not come from a new trial. Strathe and colleagues pooled pharmacokinetic and BMI data from the 201 STEP TEENS participants and about 3100 adults in the STEP program, then modelled what 1.7 mg would do. The model predicted a mean BMI change of -15.2% on 1.7 mg against -17.4% on 2.4 mg, with similar gastrointestinal adverse event profiles. Those results supported adding 1.7 mg to the adolescent label in November 2024.

That is the closest thing to lower-dose evidence in teenagers, and it is still a full therapeutic dose, not a microdose. The slow climb itself follows the same logic described in our article on the gentle ramp: stepping up gradually gives the gut time to adjust.

What is still unknown about GLP-1 medicines in teenagers?

Growth, muscle, bone and the end point

The long-term effects on growing bodies are the biggest gap. Adolescence is when muscle and bone mass build fastest, and a 2026 perspective in Childhood Obesity by Smith and colleagues argues that GLP-1 weight loss may blunt that accrual. The authors stress that longitudinal pediatric data are limited and recommend pairing treatment with resistance training, weight-bearing activity and adequate protein, the same priorities covered for adults in our article on GLP-1 and muscle retention.

The second gap is how treatment ends. A 2026 interview study of 29 adolescents and young adults and 23 caregivers found that teenagers valued the drop in appetite and food noise but worried about stigma, and that families were uncertain about when to stop. Given the rebound seen after liraglutide, that uncertainty is reasonable, and the trials do not yet answer it.

Has microdosing a GLP-1 been tested in teenagers?

What can and cannot be said

No. Every adolescent trial used full doses: semaglutide 2.4 mg weekly, liraglutide 3.0 mg daily, and tirzepatide 5 or 10 mg weekly. The lowest labeled maintenance dose for teenagers is 1.7 mg weekly, and even that rests on modelling. There are no data on sub-therapeutic or microdose regimens in anyone under 18.

The microdosing approaches discussed elsewhere on this site concern adults. For a teenager, GLP-1 treatment is a decision for a pediatrician or pediatric obesity specialist, made alongside a structured lifestyle program, which the JAMA Pediatrics meta-analysis found to be effective on its own and to make every medicine work better.

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