Methamphetamine also called meth is a very powerful stimulant. Meth has been used primarily for medical treatment in obesity, but this is limited. Meth is a white, odorless, bitter-tasting crystalline powder that dissolves in water and in alcohol. There are many different ways to take meth. The ways that people usually take it is orally, intranasally (snorting the powder), by needle injection, or by smoking. When methamphetamine enters the body it releases dopamine, which is involved in motivation, the experience of pleasure and motor function, and is a common mechanism of action for most drugs of abuse. The central nervous system (CNS) actions that result from taking even small amounts of methamphetamine include increased wakefulness, increased physical activity, decreased appetite, increased respiration, hypothermia, and euphoria. Other CNS effects include irritability, insomnia, confusion, tremors, convulsions, anxiety, paranoia, and aggressiveness. Hyperthermia and convulsions can result in death. Most people go to a rehabilitation to recover from this drug.
Melissa Opatik
AP Psychology

http://www.drugabuse.gov/infofacts/methamphetamine.html
http://www.streetdrugs.org/methamphetamine.htm