As more children take GLP-1 drugs for weight loss or diabetes, doctors are flagging a side effect that’s flown under the radar — and it has nothing to do with nausea.
A Question Doctors Weren’t Asking Loud Enough
When GLP-1 medications like Ozempic, Wegovy, and Zepbound exploded into the mainstream, most of the public conversation settled on a familiar set of concerns: nausea, “Ozempic face,” muscle loss, and whether people would regain weight after stopping. Those conversations have been almost entirely adult-focused. But quietly, a separate and much less discussed shift has been happening — these same drugs, or close relatives of them, are increasingly being prescribed to children and teenagers for obesity, prediabetes, and type 2 diabetes.
And a new study suggests that pediatric patients may be facing a risk that has gotten almost no public attention: nutritional deficiencies severe enough to require diagnosis and treatment, occurring during exactly the years when a child’s body is building the bone density, blood supply, and organ systems it will rely on for the rest of its life.
The study, conducted by researchers at Ann & Robert H. Lurie Children’s Hospital of Chicago and published in the journal Childhood Obesity, is one of the first to systematically examine what happens nutritionally to children on these medications over time. The answer is more concerning than most parents — or, frankly, most prescribing doctors — may realize.
What the Study Actually Found
The topline number is striking on its own: nearly one in six young patients — 16.8% — were diagnosed with a nutritional deficiency within the first year after starting GLP-1 treatment.
That’s not a marginal side effect buried in fine print. It’s a rate that would raise eyebrows for almost any pediatric medication, let alone one increasingly prescribed for a condition — childhood obesity — that already disproportionately affects lower-income families with less consistent access to nutritional monitoring and specialist follow-up care.
Among the deficiencies identified, vitamin D emerged as the most common single problem, affecting roughly 12% of children in the study within just one year of starting treatment. Vitamin D might sound like a minor concern compared to the headline-grabbing side effects associated with these drugs in adults, but for a growing child, it’s foundational — critical for bone mineralization, immune function, and even mood regulation during a developmental window that doesn’t get a second chance.
The medications examined in the study included liraglutide (sold under the brand names Victoza and Saxenda), along with other GLP-1 drugs such as Trulicity and Ozempic — medications prescribed to children for weight management, prediabetes, or type 2 diabetes. Liraglutide, notably, accounted for nearly 80% of the study’s participants, making it by far the most commonly prescribed GLP-1 medication among the children studied.
Why This Is Happening: It’s Not a Drug Defect, It’s How the Drug Works
To understand why nutritional deficiencies would show up as a side effect at all, it helps to understand what GLP-1 drugs are actually designed to do.
These medications work by mimicking a naturally occurring hormone called glucagon-like peptide-1, which regulates blood sugar and — crucially — appetite. GLP-1 drugs slow down digestion and send powerful “you’re full” signals to the brain, which is precisely why they’re so effective for weight loss. Patients on these medications eat meaningfully less, and what they do eat moves through their digestive system more slowly.
That’s the entire point of the drug for an adult managing obesity or type 2 diabetes. But for a child or teenager who is still growing — building bone mass, expanding blood volume, developing organ systems, and often entering puberty — eating dramatically less isn’t a neutral side effect of treatment. It’s a direct threat to the nutritional inputs that growth actually requires.
Researchers involved in the study explicitly flagged this mechanism as the likely driver of the deficiencies they observed, noting that the medications can affect appetite and food intake in ways that raise concerns about whether adolescents taking them are receiving adequate nutrition during a critical stage of development. In other words, the drug isn’t malfunctioning — it’s working exactly as intended. The problem is that “working as intended” for weight loss and “getting adequate nutrition during a growth spurt” can be directly at odds with each other in a way that simply doesn’t apply the same way to a fully grown adult.
Why Vitamin D, Iron, and Calcium Specifically Matter So Much Right Now
Justin Ryder, PhD, the study’s senior author and Vice Chair of Research for the Department of Surgery at Lurie Children’s Hospital, along with an Associate Professor role at Northwestern University Feinberg School of Medicine, was direct about why these particular nutrients demand special attention during adolescence. He noted that nutrients like vitamin D, iron, and calcium are of particular concern during this life stage, because deficiencies at this age can carry lasting implications for skeletal health and overall development.
That framing matters because it distinguishes this issue from a typical, correctable adult nutritional gap. An adult who develops mild vitamin D deficiency while on a GLP-1 medication can usually address it with supplementation and monitoring, with the underlying skeletal structure largely already in place. A child or teenager who spends a year or more with inadequate vitamin D, iron, or calcium during a period of rapid bone growth and, in many cases, active pubertal development, may not get a clean do-over. Peak bone mass — the maximum bone density a person will ever achieve — is largely established during childhood and adolescence. A prolonged deficiency during that specific window can shape someone’s skeletal health risk profile decades later, well into adulthood and old age.
Iron deficiency carries its own distinct risks for young people, including impacts on cognitive development, energy levels, and immune function — all of which are particularly consequential during years when a child is also expected to be learning, growing, and physically active.
A Medication Category Moving Faster Than the Research
Part of what makes this study significant is timing. GLP-1 drugs have exploded in popularity across all age groups over the past several years, driven by extraordinary effectiveness for weight loss and diabetes management in adults. As demand and prescribing familiarity grew, use expanded into pediatric populations — sometimes even before long-term safety data specific to children had fully caught up.
Ryder captured this tension directly, noting that as appropriate pediatric use of GLP-1 medications becomes more widespread, the field needs a much clearer understanding of the risks these drugs carry during periods of rapid growth and pubertal development. That’s a notably candid admission from a lead researcher: essentially, prescribing has been outpacing the safety data needed to prescribe responsibly.
This isn’t a new pattern in medicine — plenty of drugs get adopted for pediatric use based on adult safety data and a reasonable extrapolation of benefit, with dedicated pediatric safety research following afterward. But it does mean that families and pediatricians navigating GLP-1 treatment for a child right now are, in a meaningful sense, part of an ongoing real-world safety study, even when that’s not how the prescription conversation is framed at the pharmacy counter.
This Doesn’t Mean the Drugs Shouldn’t Be Used
It’s worth being clear about what this study is not saying. It is not an argument that GLP-1 medications are inappropriate or unsafe for children with obesity, prediabetes, or type 2 diabetes. For many young patients, these conditions carry their own serious, well-documented long-term health risks — cardiovascular disease, liver disease, orthopedic strain, and psychosocial harm among them. GLP-1 medications represent a powerful new tool for managing conditions that, until recently, had frustratingly few effective treatment options for younger patients.
Health outlets covering the study have been careful to frame it this way: GLP-1 drugs are potentially powerful tools in treating childhood obesity, but their use is not without risk, and that risk deserves active monitoring rather than either dismissal or panic.
The more useful takeaway is about how these medications are managed in pediatric patients, not whether they should be prescribed at all. A 16.8% rate of diagnosed nutritional deficiency is a strong argument for building routine nutritional monitoring into pediatric GLP-1 treatment protocols from day one — not a reason to avoid a medication that may be genuinely life-changing for a child struggling with obesity-related health complications.
What This Means for Parents Right Now
If your child or teenager is currently taking a GLP-1 medication, or your pediatrician has recommended starting one, this research points toward a few concrete, reasonable questions worth raising at the next appointment:
Ask about baseline and follow-up bloodwork. Given that vitamin D, iron, and calcium were the specific nutrients flagged as concerns, it’s reasonable to ask whether your child’s levels were checked before starting treatment and whether periodic monitoring is built into their care plan — ideally at intervals more frequent than a routine annual physical, particularly during the first year.
Ask about nutritional counseling, not just the prescription. Because these drugs work by suppressing appetite, a child on GLP-1 treatment may need more intentional guidance on how to make the food they do eat nutritionally dense, rather than simply eating less of whatever they’d normally choose. A referral to a registered dietitian familiar with pediatric GLP-1 use can be a meaningful addition to a treatment plan, not an optional extra.
Watch for supplementation needs. If deficiencies do show up, they are generally treatable with targeted supplementation — but only if they’re caught. Given that this study found deficiencies emerging within the first year, that window deserves particular attention rather than a “we’ll check next year” approach.
Don’t stop or adjust medication without medical guidance. It can be tempting, on reading a headline like this one, to want to pull back on a child’s treatment immediately. That instinct is understandable, but GLP-1 medications, particularly at pediatric doses, should only be started, adjusted, or stopped under a physician’s supervision — the underlying condition being treated often carries its own serious risks if left unmanaged.
The Bigger Picture: A Preventable Blind Spot
What makes this finding particularly frustrating, in a constructive sense, is that it appears to be a genuinely preventable problem rather than an unavoidable consequence of the medication itself. Nutritional deficiencies are, generally speaking, detectable through routine bloodwork and correctable through supplementation and dietary support. This isn’t a side effect on the level of an unpredictable, hard-to-manage organ complication — it’s a monitoring and management gap.
That reframes the real news here. It’s not that GLP-1 drugs are secretly dangerous for children in some previously hidden way. It’s that pediatric prescribing practices for a genuinely new and fast-growing category of medication haven’t fully caught up to the reality of how these drugs affect a still-growing body differently than a fully developed adult one. As Ryder’s team put it, understanding these risks during periods of rapid growth and pubertal development is now essential precisely because pediatric use is expanding so quickly.
For a drug category that has already transformed obesity and diabetes treatment for millions of adults, extending that same transformative potential safely to children may come down to something refreshingly unglamorous: better bloodwork, more consistent follow-up, and dietitians built into the treatment team from the start.
