INTRO: We present a case of drug-induced liver injury (DILI) associated with N.O.Xplode®, a commonly used creatine blend pre-workout supplement. Due to the lack of stringent regulation of herbal and dietary supplements (HDS), it is important to consider DILI when treating patients with unexplained liver injury. To our knowledge, this is only the second case that can definitively be attributed to this particular supplement. CASE REPORT: A 42-year-old male with no history presented with three weeks of abdominal pain, diarrhea, weight loss, nausea, vomiting, pruritis, and jaundice. An outpatient workup found elevated liver function tests (LFTs), as well as diffuse enlargement of his liver. He was referred to our institution for further workup. On initial evaluation, he endorsed crampy upper quadrant pain worse after eating, as well as constant diarrhea and a 13-pound weight loss. Over the past week, he noticed pale, chalky stools and dark urine but no hematochezia or melena. He denied recent antibiotics, sick contacts, or travels. He admitted to rare use of Tylenol but denied any alcohol or illicit drug use. He worked out 5 days a week and used a weight-building supplement called N.O.Xplode® before each workout. He was on no other medications and had no family history of liver disease. Physical exam found scleral icterus, jaundice, and mild RUQ tenderness on palpation without hepatomegaly or shifting dullness. Laboratory data are detailed in Table 1. Workup for causes of chronic liver disease, including imaging, were negative. After clinical improvement, patient was discharged and an outpatient liver biopsy was performed. Findings were concerning for drug induced injury with no evidence of balloon degeneration, steatosis, plasma cells, fibrosis, or necrosis. The patient discontinued the supplement and was started on ursodeoxycholic acid with resolution of his symptoms.Table: Table. Laboratory dataDISCUSSION: DILI is a leading cause of acute liver failure in the US, with HDS as an increasingly common cause, accounting for more than 7% of cases. Patients on HDS have a more protracted course of liver injury. It took 5 months for our patient's hepatic function to normalize. Risk factors of idiopathic DILI are not clear. Recent data has shown that almost half of U.S. adults use some sort of dietary supplement. Therefore, it may be useful to initiate a population-based study to investigate the causes and incidence in the US, which may help in future regulation of such products.