MDMA (3,4-Methylenedioxymethamphetamine), also known as Ecstasy (abbreviated E, X, or XTC), molly (U.S.), or mandy (U.K.), is a psychoactive drug with stimulant and psychedelic effects that is primarily used as a recreational drug. Drugs sold under the street names ecstasy, molly, or mandy are often advertised as pure MDMA, but are often mixed with multiple other drugs. MDMA can cause feelings of euphoria (extreme happiness) and altered sensations. Bad side effects include insomnia, nausea, rapid heartbeat, and addiction. It causes an initial increase in neurotransmitters that is followed by a short-term drop in neurotransmitters, which can lead to severe depression after coming down from the high.