Warning Issued Over Potentially Dangerous 'Off-Brand' GLP-1 Medications

Daily Technology

13/03/2026

Eli Lilly, the manufacturer of popular GLP-1 drugs like Mounjaro and Zepbound, has issued a public warning regarding compounded versions of their medications. These "off-brand" alternatives, often mixed with ingredients like vitamin B12, may contain concerning impurities and pose unknown risks to patients seeking a more affordable option.

Key Takeaways

Compounded GLP-1 medications, often marketed as cheaper alternatives, may contain dangerous impurities.
Eli Lilly has identified "significant levels of an impurity" in tirzepatide-B12 products.
Health authorities and drug manufacturers are urging caution against these custom formulations.
Compounded drugs bypass the rigorous safety and effectiveness testing required for FDA-approved medications.

The Risks of Compounded GLP-1s

Compounded drugs are custom-made medications prepared by pharmacies. While this service has its place, it has been exploited to create unauthorized versions of GLP-1 drugs, such as semaglutide (Ozempic, Wegovy) and tirzepatide (Mounjaro, Zepbound), especially during periods of shortage. These compounded versions have been significantly cheaper than the brand-name counterparts, which are often not covered by insurance.

Pharmacies have claimed to customize these drugs by adding ingredients like vitamin B12, glycine, pyridoxine, and others, marketing them as enhanced formulations. However, the U.S. Food and Drug Administration (FDA) has attempted to curb the mass marketing and distribution of these compounded GLP-1s, deeming them likely illegal. Both Eli Lilly and Novo Nordisk (maker of semaglutide) have taken legal action against distributors of these copycat drugs.

Eli Lilly's Findings

As part of its efforts to combat these unauthorized products, Eli Lilly conducted tests on compounded tirzepatide and B12 mixtures. The company reported finding impurities that could result from a chemical reaction between tirzepatide and vitamin B12. These findings have been shared with the FDA.

Eli Lilly stated, "People receiving tirzepatide-B12 products from compounders, telehealth companies, medspas, or anyone else should be aware that they may be using a potentially dangerous product with unknown risks."

Regulatory Concerns and Adverse Events

The FDA has received reports of compounded GLP-1s being inadequately refrigerated or made with low-quality ingredients. In some instances, patients have received compounded medications labeled as coming from pharmacies that did not actually produce them or may not even exist. Adverse events associated with these compounded drugs have included redness, swelling, pain at the injection site, and lumps.

Recently, Hims, a prominent provider of compounded GLP-1s, announced it would cease marketing these drugs as part of an agreement with Novo Nordisk. This development, coupled with increasing legal pressure and the declining prices of authorized GLP-1 medications, may signal a shift away from the compounded market.

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