Amphetamine drug, molecular model. Amphetamine (C9H13N) is a stimulant and appetite suppressant that is illegal in most countries. It is commonly known by the slang name speed". Atoms are shown as spheres and are colour-coded: carbon (grey), hydrogen (white) and nitrogen (blue). As well as being taken recreationally for its energising effects, the drug is also used as an appetite suppressant by those wanting to lose weight, and as a stimulant by those who want to stay awake, for instance for long night shift work. In medicine the drug is used to treat narcolepsy (uncontrollable sleeping) and attention deficit hyperactivity disorder (ADHD)."