Tehran University of Medical Sciences Journal of Pharmaceutical Care 2322-4630 13 3 2025 12 03 238 242 Azam Erfanifar Department of Endocrinology, Loghman Hakim Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran Mahdiye Abiyarghamsari Department of Clinical Pharmacy, School of Pharmacy, Shahid Beheshti University of Medical Sciences, Tehran, Iran Afshin Zarghi Department of Pharmaceutical Chemistry, School of Pharmacy, Shahid Beheshti University of Medical Sciences, Tehran, Iran 2025 04 04 2025 08 03 This case report highlights the adulteration of over-the-counter weight gain supplements with undeclared glyburide, culminating in a life-threatening episode of hypoglycemia in a healthy young adult. A previously healthy 23-year-old man was admitted to the emergency department on April 10, 2022, following a brief episode of unconsciousness. Upon arrival, his blood glucose was found to be 30 mg/dL. He reported having taken one herbal weight-gain tablet daily for the preceding three days. His blood glucose level quickly returned to normal after an intravenous dextrose infusion. Liquid chromatography-mass spectrometry (LC-MS) analysis of the tablets detected the presence of glyburide. The patient did not experience any further hypoglycemic episodes while being monitored and was discharged in stable condition after a four-day hospitalization. This case highlights the significant risk posed by undeclared sulfonylurea adulteration in unregulated herbal supplements, as well as the importance of implementing routine post-market quality control and toxicological screening to protect public health and prevent serious adverse events. https://jpc.tums.ac.ir/index.php/jpc/article/view/828 https://jpc.tums.ac.ir/index.php/jpc/article/download/828/424