There are two basic kinds of hepatotoxicity. One is the predictable, or toxin-produced, and the other is the unpredictable, or the hypersensitivity response. Toxicity is usually dose-related and is noticed within a fixed time frame from exposure. The more common examples are acetaminophen, carbon tetrachloride, isoniazid, and the toxin of the Amanita phalloides mushroom. Acetaminophen causes toxicity by accumulation of its toxic intermediate when hepatic glutathione reserves are depleted. This occurs most commonly in persons with underlying liver disease and in alcoholics. Carbon tetrachloride and Amanita phalloides cause liver damage through development of free radicals that produce lipid peroxidation in the cell membrane. These cell reactions are precursors to eventual liver cell necrosis; however, the exact mechanism of necrosis is still unknown. Drugs causing unpredictable responses or hypersensitivity include chlorpromazine, allopurinol, alpha-methyldopa, isoniazid, and halothane.