Methamphetamine is a powerful stimulant that activates certain systems in the brain. It is closely related chemically to amphetamine, but the central nervous system effects of methamphetamine are greater. Both drugs have some medical uses, primarily in the treatment of obesity, but their therapeutic use is limited. 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.
Illicit methamphetamine, which is almost exclusively methamphetamine hydrochloride, is sold in powder, ice, and tablet forms. Powder methamphetamine, the most common form available in the United States, is produced domestically and also is smuggled into the country from Mexico. Traditionally, Asian-produced ice was almost exclusively found in Guam, Hawaii, and parts of California; however, increased domestic production of this form of methamphetamine has increased availability to several other areas of the country previously untouched by exposure to ice. Methamphetamine tablets, primarily manufactured in Burma, have been smuggled into the United States, especially to northern California and the Los Angeles area.