Ampyrone (4-Aminoantipyrine or AAP) is a metabolite of aminophenazone and is an aromatic substance with analgesic, antipyretic and anti-inflammatory properties. When combined with the antineoplastic agents, ampyrone decreased their genotoxic, mutagenic, apoptotic, and phagocytic effects. However, ampyrone usually produces side effects, such as the risk of agranulocytosis. Although ampyrone is scarcely ever administered as an analgesic because of the potential side effects, as a raw material, it is mostly used to produce ampyrone derivatives, which have better biological activities. In addition, it is used as a reagent for biochemical reactions producing peroxides or phenols and can also be used to detect phenols in the environment. Exposure to ampyrone could induce changes in the enzyme catalase structure and function.