What is the black box warning on GLP-1 medications?

GLP-1 medications carry an FDA black box warning - the most serious warning the FDA issues - regarding the risk of thyroid C-cell tumors. This warning is based on rodent studies showing that rodents exposed to GLP-1 agonists developed medullary thyroid carcinoma (MTC) at clinically relevant doses. However, it's important to understand that rodents have much higher densities of GLP-1 receptors in their thyroids than humans, making them more susceptible to this effect. No increased risk of thyroid cancer has been observed in human clinical trials or post-marketing surveillance of millions of patients. The warning states these medications are contraindicated in patients with a personal or family history of medullary thyroid carcinoma or Multiple Endocrine Neoplasia syndrome type 2 (MEN2). For patients without these specific risk factors, the absolute risk appears extremely low. Report any symptoms of thyroid tumors to your doctor: lump in the neck, hoarseness, difficulty swallowing, or shortness of breath.