Increased effect/toxicity w/ barbiturates, carbamazepine, hydantoins, INH, rifampin, chronic ethanol abuse. Increased hepatotoxic potential w/ sulfinpyrazone. Enhanced effect of warfarin. Decreased effect w/ barbiturates, carbamazepine, hydantoins, rifampin. Decreased analgesic effect w/ sulfinpyrazone. Decreased absorption w/ cholestyramine & food. Increased risk of acetaminophen-induced hepatotoxicity w/ ethanol. Decreased levels w/ St John's wort.