A 28-year-old man, recently emigrating from the Philippines, was noted to have a positive tuberculin skin test result in the clinic. His chest radiograph showed no active tuberculosis, and he denied any symptoms of this infection, including weight loss, cough, or night sweats. To prevent future disease, daily dosing with isoniazid was recommended for the next 9 months. Two weeks after initiating therapy, the patient reported progressive fatigue, intermittent bouts of nausea, and abdominal pain. He also noticed darkening of his urine and light-colored stools. His sister noted a gradual yellowing of his eyes and skin. Blood tests showed a marked increase in serum bilirubin and aminotransferases. The isoniazid was discontinued, and his symptoms subsided with normalizing of his liver enzymes
