We describe refractory postoperative hypotension due to adrenal insufficiency in a patient treated with steroid-adulterated herbal medicine. A 62-year-old man underwent an elective total hip replacement. Surgery was uneventful, but he became profoundly hypotensive 8 hours later, requiring intensive care unit admission, intubation, vasopressor support, and renal replacement therapy. Subsequent workup revealed that he had been consuming a herbal medication adulterated with prednisolone. Adrenal insufficiency secondary to chronic exogenous steroids was diagnosed following cortisol measurements and an adrenocorticotropic hormone stimulation test. He responded well to steroid therapy and made a full recovery. The use of herbal medicine should not be overlooked.