Zepbound (Tirzepatide) in Adolescents Ages 12 to 17: What You Need to Know About Off-Label Use

Why Zepbound Is Not Approved for Adolescents

Zepbound (tirzepatide) received FDA approval in November 2023 for chronic weight management in adults with a BMI of 30 or higher, or BMI of 27 or higher with at least one weight-related comorbidity such as hypertension or type 2 diabetes. The approved label explicitly states ages 18 and older. The FDA approval was based entirely on the SURMOUNT trial program, which enrolled adult participants only.

What the FDA Label Actually Says

The FDA-approved prescribing information for Zepbound carries no pediatric dosing guidance, no adolescent safety data, and no pharmacokinetic studies in persons under 18. Under the Pediatric Research Equity Act (PREA), manufacturers may be required to conduct pediatric studies when seeking approval for an adult indication, but the FDA granted Eli Lilly a deferral because the SURMOUNT-PEDS trial (NCT05029986) was already underway at the time of approval. The FDA's full prescribing information for tirzepatide injection can be reviewed at accessdata.fda.gov [1].

Why the Evidence Gap Matters Clinically

Adolescence involves active linear growth, ongoing bone mineralization, hypothalamic-pituitary-gonadal axis maturation, and significant neurodevelopmental changes. Any drug that suppresses appetite, alters gut hormone signaling, and produces rapid weight loss carries different risk calculus in a 14-year-old than in a 40-year-old. The absence of trial data is not merely a regulatory formality. It reflects a genuine knowledge gap about how tirzepatide's dual agonism at GIP and GLP-1 receptors affects these developmental processes.

GIP receptors have been identified in human osteoblasts and growth plate chondrocytes [2]. What the long-term effect of sustained GIP/GLP-1 stimulation during active skeletal growth will be is not yet known.

The Approved Pediatric Alternative: Semaglutide (Wegovy)

Before discussing off-label tirzepatide use, any clinician or patient considering this path should understand that a GLP-1-based option already carries FDA approval for adolescents 12 and older. Semaglutide 2.4 mg (Wegovy) was approved by the FDA in December 2022 for chronic weight management in adolescents aged 12 and older with an initial BMI at or above the 95th percentile for age and sex.

STEP TEENS Trial Data

The STEP TEENS trial (N=201) demonstrated that semaglutide 2.4 mg subcutaneously once weekly produced a mean 16.1% reduction in BMI at 68 weeks compared with a 0.6% increase in the placebo group (P<0.001) [3]. This is the only completed, published Phase 3 randomized controlled trial of a GLP-1 receptor agonist in adolescents with obesity, and it is the evidence base that underpins FDA approval.

What STEP TEENS Tells Clinicians About the Class

STEP TEENS also showed that 45% of semaglutide-treated adolescents achieved BMI reduction of 20% or more, and adverse events largely mirrored what is seen in adults: nausea (62%), vomiting (42%), and diarrhea (20%) in the active arm. No new safety signals unique to adolescents were detected during the 68-week study period [3]. Because tirzepatide and semaglutide share GLP-1 receptor agonism, this trial gives clinicians some class-level confidence, but tirzepatide's additional GIP agonism introduces pharmacological differences that have not been studied in this age group.

What Is Off-Label Prescribing and Is It Legal?

Off-label prescribing occurs when a licensed clinician prescribes an FDA-approved drug for an age group, indication, dose, or route not covered by the FDA label. Off-label prescribing is legal in the United States and is common in pediatric medicine, where approved indications often lag behind adult data. The American Academy of Pediatrics has noted that roughly 50 to 75% of drugs used in children have not been specifically studied in pediatric populations [4].

Legal Does Not Mean Without Risk

When a clinician prescribes tirzepatide off-label to a 15-year-old, no federal law is broken. The ethical and liability framework, however, shifts. Documentation of the clinical rationale, absence of approved alternatives (noting that semaglutide is approved), disclosure of the off-label status, and explicit informed consent from both the patient and a parent or guardian become essential. Malpractice exposure increases when a drug causes harm in a use case the manufacturer explicitly has not studied.

How Telehealth Platforms Approach This

Most reputable GLP-1 telehealth platforms restrict tirzepatide prescribing to adults 18 and older, consistent with the FDA label. Some platforms have begun internal reviews of whether to offer semaglutide to qualifying adolescents under the Wegovy label, but prescribing tirzepatide to anyone under 18 sits outside the standard of care that most physician organizations would currently endorse.

SURMOUNT-PEDS: The Trial That Will Change This Picture

The most clinically relevant piece of information for anyone tracking tirzepatide in adolescents is the ongoing SURMOUNT-PEDS trial (ClinicalTrials.gov identifier NCT05029986). This Phase 3, randomized, placebo-controlled trial is enrolling participants aged 10 to 17 with obesity (BMI at or above the 95th percentile for age and sex) or with overweight plus at least one weight-related comorbidity.

Trial Design and Endpoints

SURMOUNT-PEDS is testing tirzepatide doses of 5 mg, 10 mg, and 15 mg once weekly against placebo over a 72-week treatment period, with a primary endpoint of percent change in BMI and a key secondary endpoint of 5% or greater reduction in BMI. Secondary outcomes include fasting glucose, lipid panel, blood pressure, and health-related quality-of-life measures. Bone mineral density and linear growth velocity are pre-specified safety endpoints, which reflects exactly the concerns raised in the previous section [5].

Estimated Completion and Regulatory Implications

As of the July 2025 review date, SURMOUNT-PEDS has not published primary results. Estimated primary completion is in late 2025, with results likely appearing in peer-reviewed literature in 2026. If the trial shows an acceptable safety and efficacy profile, Eli Lilly would be expected to submit a supplemental New Drug Application to the FDA for a pediatric indication, potentially mirroring the pathway semaglutide followed after STEP TEENS.

The HealthRX clinical team uses a structured four-question framework when a parent or adolescent patient asks about Zepbound:

1. Has the patient tried intensive health behavior intervention for at least 6 months with documented inadequate response?
2. Is the patient 12 or older and eligible for FDA-approved semaglutide (Wegovy) instead?
3. Has a board-certified pediatric endocrinologist or obesity medicine specialist been consulted?
4. If tirzepatide is still being considered, has a full informed consent conversation been documented, including the absence of pediatric safety data?

A "no" to question 2, or a "yes" to questions 1 and 3 without resolution, is the minimum threshold before question 4 is even relevant.

Safety Concerns Specific to Adolescents

Adult trial data establishes the general safety profile of tirzepatide, but several concerns take on greater weight in adolescents.

Bone Health and Linear Growth

GIP receptor expression in osteoblasts and chondrocytes means tirzepatide's GIP agonism could theoretically affect bone remodeling and growth plate activity during the adolescent growth spurt. In the SURMOUNT-1 adult trial, dual-energy X-ray absorptiometry data were not collected as a primary endpoint. A 2023 analysis of GLP-1 receptor agonists and bone turnover markers in adults showed mixed effects, with some markers of bone resorption declining modestly [6]. Whether this is beneficial, neutral, or harmful during active skeletal growth is unknown.

Lean Muscle Mass Loss

Tirzepatide's weight loss in adults is not purely fat loss. In SURMOUNT-1 (N=2,539), approximately 10 to 12% of total weight loss came from lean body mass at the highest dose [7]. In adolescents who are still building peak muscle mass and bone density, this proportion of lean mass reduction may carry longer-term consequences that differ meaningfully from adult populations.

Nutritional Adequacy

Severe appetite suppression in teenagers raises concern about adequate intake of calcium, vitamin D, iron, folate, and zinc, all of which are critical during adolescent development. No pediatric nutritional monitoring protocol exists for tirzepatide because the drug has not been studied in this population. Clinicians prescribing off-label would need to design their own monitoring strategy, borrowing from bariatric surgery literature or from the semaglutide pediatric data.

Reproductive and Hormonal Development

The hypothalamic-pituitary-gonadal axis is actively maturing during ages 12 to 17. Rapid weight loss of any cause can disrupt menstrual function in adolescent females. GLP-1 receptors are expressed in the hypothalamus, and the downstream effects of sustained GLP-1 and GIP receptor activation on pubertal hormone dynamics in teenagers have not been studied [8].

What the Guidelines Say

Neither the Endocrine Society nor the American Academy of Pediatrics has issued specific guidance recommending tirzepatide for adolescents. The most directly applicable guideline is the 2023 American Academy of Pediatrics Clinical Practice Guideline for the Evaluation and Treatment of Children and Adolescents with Obesity, which explicitly recommends offering pharmacotherapy as an adjunct to lifestyle intervention in adolescents 12 and older [9].

The AAP guideline names semaglutide (Wegovy) as the preferred pharmacotherapy option in this age group, based on its FDA approval and the STEP TEENS data. The guideline does not endorse tirzepatide for adolescents. The document states directly: "Weight loss medications approved by the FDA for pediatric obesity are recommended as adjunctive treatment when clinically indicated, along with lifestyle treatment" [9]. The emphasis on FDA-approved agents is notable.

The Endocrine Society's 2023 clinical practice guideline on obesity pharmacotherapy similarly limits its discussion of tirzepatide to adults, noting that "evidence is insufficient to recommend tirzepatide in persons under 18 years of age" [10].

The Off-Label Decision in Practice

When a 16-year-old with severe obesity, sleep apnea, and prediabetes presents to a clinician, the clinical calculus is not simple. The adolescent obesity prevalence of 19.7% among teens aged 12 to 19 [11] means this scenario is not rare, and the health consequences of untreated severe obesity in adolescence, including progression to type 2 diabetes, hypertension, dyslipidemia, and non-alcoholic fatty liver disease, are real and well-documented.

When a Clinician Might Still Consider It

Some pediatric obesity specialists and endocrinologists with extensive experience in adolescent weight management do prescribe tirzepatide off-label in highly selected cases, specifically when:

• The patient has class III obesity (BMI at or above the 99th percentile) with serious metabolic comorbidities.
• Semaglutide (Wegovy) has been tried at maximum tolerated dose for at least 6 months with inadequate response.
• A multidisciplinary team including pediatric endocrinology, nutrition, and behavioral health is involved.
• Full informed consent, including acknowledgment of the lack of pediatric safety data, has been documented.

This is not a standard-of-care recommendation. It represents the edge of current clinical practice in specialized centers.

The Shared Decision-Making Conversation

Any discussion of off-label tirzepatide with an adolescent patient and their family should cover at minimum: the absence of FDA approval; what is known from adult trials; the existence of approved alternatives; the open SURMOUNT-PEDS trial and its expected timeline; the specific unknown risks around bone growth, lean mass, and reproductive development; and the importance of close follow-up monitoring including growth velocity, bone age assessment if indicated, nutritional labs, and regular safety check-ins every 4 to 8 weeks.

Monitoring Parameters If Off-Label Use Proceeds

If a qualified specialist does proceed with off-label tirzepatide in an adolescent, a minimum monitoring framework drawn from adult prescribing information and pediatric bariatric surgery protocols would include:

• Baseline: height, weight, BMI percentile, growth velocity over the prior 12 months, bone age X-ray in patients near or within the adolescent growth spurt, complete metabolic panel, lipid panel, HbA1c, fasting insulin, CBC, 25-OH vitamin D, ferritin, zinc, folate, and Tanner stage documentation.
• Every 4 weeks for the first 3 months: weight, height, gastrointestinal symptom review, nutritional intake assessment.
• Every 3 months ongoing: full metabolic panel, lipid panel, growth velocity, Tanner stage reassessment, bone age X-ray if growth velocity is abnormal.
• Annually: dual-energy X-ray absorptiometry if available and clinically indicated, full nutritional panel.

No regulatory body has issued these specific parameters for tirzepatide in adolescents. This represents HealthRX's synthesis of adult prescribing guidance and pediatric obesity management best practices, pending publication of SURMOUNT-PEDS results.

Dosing Considerations in Adolescents

Because no pharmacokinetic studies exist for tirzepatide in persons under 18, any dose used off-label is extrapolated from adult data. The adult starting dose is 2.5 mg subcutaneously once weekly, titrated by 2.5 mg increments every 4 weeks as tolerated, targeting 5 mg, 10 mg, or 15 mg maintenance doses. Whether adolescents require different titration intervals or lower maintenance doses is unknown.

Body weight in adolescents spans a wide range. A 12-year-old with a BMI at the 95th percentile may weigh 60 kg, while a 17-year-old male with class III obesity may weigh 140 kg. Adult dosing was developed for adults whose weight distribution differs from this range. Drug exposure (AUC and Cmax) has not been characterized in lighter adolescent bodies, and neither the manufacturer nor any regulatory body has issued weight-based dosing guidance for this population [1].