Introduction: Thyroid storm is a rare but potentially life-threatening metabolic disorder that presents unique management challenges in the emergency department. Thionamides are commonly used as monotherapy for first-line treatment of hyperthyroidism.

Case Report: In this case, a 26-year-old male presented to the emergency department with sore throat, fever, and diarrhea. He was found to have thyrotoxicosis as well as methimazole-induced bone marrow suppression resulting in agranulocytosis.

Conclusion: Thyroid storm is a rare condition that carries a high risk of mortality and can further compromise a patient’s immune system due to complications of common treatment modalities. It can potentially be misdiagnosed as sepsis due to tachycardia, febrile state, and tachypnea. This case report includes a discussion of diagnostic studies, as well as medical and surgical treatment modalities that led to the patient’s recovery.