Eli Lilly has alerted the public to the potential dangers associated with compounded versions of tirzepatide mixed with vitamin B12[3]. Laboratory tests revealed high levels of the impurity, which is produced by a chemical reaction between tirzepatide and vitamin B12[3]. The company stated that nothing is known about the short-term or long-term effects of this impurity on the human body[3]. Possible risks include reduced drug efficacy, toxicity, and immune responses[3]. Tirzepatide is approved and tested only in the form of subcutaneous injections, not in compounded forms with additives[2]. Eli Lilly has informed the FDA of its findings and is calling on the FDA to ban bulk sales of unapproved compounded versions of tirzepatide[3]. People receiving tirsepatide with vitamin B12 from telemedicine companies, pharmacies, or wellness centers should be aware that they may be using a potentially dangerous product with unknown risks[3].