Nebraska study finds compounded GLP-1 weight-loss prescriptions reached 86% of compounded weight-loss prescriptions in 2025

Researchers analyzed Nebraska prescription dispensing records to describe the composition of compounded GLP-1 weight-loss medicines, a category that includes GLP-1 receptor agonists mixed with other active ingredients. The study, published in JAMA, found that compounded GLP-1 prescriptions increased from zero in 2018 to 86% of all compounded weight-loss prescriptions in 2025. The authors said the products are often obtained online and paid for in cash, making them difficult to detect in ordinary insurance claims.

The evidence is observational. Using Nebraska's unusually complete prescription tracking system, the team counted filled compounded weight-loss prescriptions and identified coformulated ingredients. The most common additives were vitamin B12 analogs, including cyanocobalamin, and levocarnitine, a molecule involved in metabolism. These additives are marketed as reducing GLP-1 side effects, but the study notes there is little evidence they work and no safety testing for the combinations. The data show dispensing patterns, not patient outcomes. Nebraska's tracking system may not represent other states.

The finding sits at the intersection of drug supply and regulation. FDA-approved GLP-1 drugs were tested as defined products, while compounded versions can be mixed in pharmacies under state oversight, often with ingredients that do not have FDA-reviewed evidence for the final combination. Because many users pay cash and buy online, routine claims-based safety monitoring can miss adverse events. The study authors call for better tracking and safety standards for compounded medicines.

The stakes are large because GLP-1 use has expanded rapidly and compounded products may reach patients who are not captured in pharmacy records. The study cannot show harm from B12 analogs or levocarnitine, nor prove that compounded products are unsafe; it shows an unmonitored market where composition and quality may be unverifiable. The next evidence should link dispensing records to clinical outcomes, adverse-event reports, and laboratory testing of product composition in representative users.