甲基苯丙胺或甲基安非他命（methamphetamine），其盐酸盐或硫酸盐又称冰毒，微带苦味，呈白色或无色，为结晶体或粉末状，易溶于水，是一种人工合成的兴奋剂。属苯乙胺类。甲基苯丙胺可使机体产生强烈快感，并具成瘾性。此物质呈对映异构现象，分别为左、右旋甲基苯丙胺。

Methamphetamine (contracted from N-methylamphetamine) is a strong central nervous system (CNS) stimulant that is mainly used as a recreational drug and less commonly as a treatment for attention deficit hyperactivity disorder and obesity. Methamphetamine was discovered in 1893 and exists as two enantiomers: dextromethamphetamine and levomethamphetamine. Methamphetamine properly refers to a specific chemical, the racemic free base, which is an equal mixture of levomethamphetamine and dextromethamphetamine in their pure amine forms. It is rarely prescribed due to concerns involving human neurotoxicity and potential for recreational use as an aphrodisiac and euphoriant, among other concerns, as well as the availability of safer substitute drugs with comparable treatment efficacy. Dextromethamphetamine is a much stronger central stimulant than levomethamphetamine. Both enantiomers are neurotoxic and addictive.