The study, led by Clement P. Buclin of Geneva University Hospitals and the University of Geneva together with colleagues across Swiss and Canadian institutions, was conducted between March and June 2025. The researchers embedded questions on GLP-1 receptor agonist use into an omnibus survey run with the Swiss Federal Office for Statistics, using a probabilistic sampling design so that the 5,818 respondents surveyed could be weighted to represent 7.43 million individuals nationwide. This approach matters because most existing evidence on GLP-1 uptake comes from prescription databases or insurance claims, which capture only the formal, physician-mediated pathway. By asking people directly, the team could detect use that never appears in any pharmacy record, including medications bought abroad, obtained through informal networks, or shared within households.

The headline prevalence figure of 2.5 percent, with a 95 percent confidence interval of 2.1 to 3.0 percent, may sound modest, but it translates into a substantial population burden for a drug class that requires ongoing injections, careful dose titration, and monitoring for gastrointestinal and other adverse effects. Semaglutide emerged as the most frequently reported agent, consistent with its dominance in both diabetes and obesity treatment guidelines and its outsized presence in public discourse. The finding that weight loss, rather than glycemic control, was the primary indication among most users underscores how thoroughly these agents have been repositioned in the public mind from diabetes drugs to lifestyle medications, a shift that regulators and clinicians are still catching up with.

Statistically, the survey revealed that use was strongly patterned by body size and, intriguingly, by perceived weight status. In multivariable models adjusting for other factors, participants reporting important overweight had nearly seven times the odds of using a GLP-1 receptor agonist compared with those reporting normal weight, with an odds ratio of 6.94 and a confidence interval of 3.01 to 16.02. Among those with a body mass index of 35 kilograms per square meter or higher, the odds ratio climbed to 8.54, with a confidence interval of 4.34 to 16.81. These gradients are exactly what clinical guidelines would predict, since obesity indications are typically reserved for people with a BMI of 30 or above, or 27 and above with weight-related comorbidities. The fact that the observed association tracks BMI so cleanly suggests that, at the population level, the drugs are at least reaching the populations for which they were designed.

One of the more unexpected results concerned gender. Despite the intense marketing of these drugs toward women in popular media, and despite women’s generally higher engagement with weight-loss interventions, the survey found no independent association between gender and GLP-1 receptor agonist use once age, BMI category, and self-reported weight status were accounted for. Age, by contrast, was independently associated with use, with the relationship varying across the lifespan in ways the authors suggest reflect both the epidemiology of obesity and prescribing caution in older adults. This dissociation between perceived demand and actual use patterns is a useful corrective to anecdotal impressions and highlights why representative surveys remain indispensable even in an era of big prescription data.

The most policy-relevant finding, however, lies in the informal access pathway. Among users, 7.3 percent reported obtaining the medication at least once outside physician-led prescribing pathways, or passing it forwards to family and friends. Weighted to the national level, that corresponds to more than 13,500 individuals in Switzerland. In practical terms, this means vials and pens intended for a single named patient are being split, lent, or sold within social networks, a practice with real pharmacological consequences. GLP-1 receptor agonists require individualized dose escalation, screening for contraindications such as personal or family history of medullary thyroid carcinoma or pancreatitis, and monitoring for red-flag symptoms. A medication borrowed from a friend arrives with none of that scaffolding, and the person receiving it may not even know the correct injection technique or storage requirements.

Perhaps most telling is who these informal users are. The study found that people reporting informal access were younger, more likely to be single, and more likely to report normal weight than formal-pathway users. That profile, young, socially connected, and not meeting conventional obesity thresholds, paints a picture of cosmetic or preventive use flowing through peer networks rather than medical channels. It also raises the possibility that informal access functions as a workaround for people who cannot obtain a prescription because they do not meet clinical criteria, or who face cost barriers, waiting lists, or reluctance to discuss weight with a physician. Whatever the mechanism, the direction is clear: the tighter the formal gatekeeping, the greater the incentive to find the drug elsewhere, and the younger the population doing so.

The clinical implications extend beyond Switzerland. Semaglutide and related agents such as tirzepatide act on the GLP-1 receptor to slow gastric emptying, enhance satiety, and improve insulin secretion in a glucose-dependent manner, effects that translate into substantial average weight reductions in trials but also into nausea, vomiting, and, rarely, more serious events such as pancreatitis and gallbladder disease. Discontinuation typically leads to weight regain, meaning these are long-term therapies, not short courses. When use migrates into informal channels, the risks multiply: no baseline assessment, no titration schedule, no adverse-event reporting, and no mechanism for detecting counterfeit or improperly stored products. Regulators across Europe and North America have already warned about compounded and counterfeit semaglutide circulating outside legitimate supply chains, and the Swiss data provide a quantitative estimate of how much informal circulation may underlie those warnings.

The authors argue that informal access among younger adults with lower BMI warrants both clinical and policy attention, and the survey gives policymakers a baseline against which future interventions can be measured. Possible responses include clearer public communication about who benefits from these drugs and who does not, tighter stewardship of the supply chain, and better access to structured obesity care so that patients are not pushed toward informal sources by default. The study also demonstrates the value of the omnibus survey model: by piggybacking a small set of well-designed items onto an existing national survey, the team produced actionable prevalence estimates at modest cost, funded by the Department of Medicine at Geneva University Hospitals, with no role for the funder in design, analysis, or reporting.

As GLP-1 receptor agonists continue their march from specialty clinics into everyday life, the Swiss survey offers a template for surveillance that other countries would do well to copy. It quantifies not just how many people use these drugs, but who uses them, why, and through which channels, revealing a hidden layer of informal circulation concentrated among the young and the slim. If the global trajectory of these medications mirrors what Switzerland is already experiencing, the coming years will see informal access grow alongside legitimate prescribing, and health systems will need data of exactly this kind to keep the balance between access and safety. For now, the message is sobering: the Ozempic era is not only bigger than prescription records suggest, it is also less visible, less supervised, and younger than most clinicians might assume.

Subject of Research: Population-level use and informal access pathways of GLP-1 receptor agonists in Switzerland

Article Title: Use and informal access to GLP-1 receptor agonists in Switzerland: a national survey

Article References: Buclin, C. P., Bonnet, R., Mongin, D., de Marcos, L., Reny, J.-L., Agoritsas, T., & Courvoisier, D. S. (2026). Use and informal access to GLP-1 receptor agonists in Switzerland: a national survey. BMC Medicine. https://doi.org/10.1186/s12916-026-05206-y

Image Credits: AI Generated

DOI: 10.1186/s12916-026-05206-y

Keywords: GLP-1 receptor agonists, semaglutide, obesity, weight loss, Switzerland, national survey, informal access, prescription drugs, self-medication, BMI, public health, drug safety