amphetamine (ămfĕt´əmēn), any one of a group of drugs that are powerful central nervous system stimulants. Amphetamines have stimulating effects opposite to the effects of depressants such as alcohol, narcotics, and barbiturates. They raise the blood pressure by causing the body to release epinephrine, postpone the need for sleep, and can reverse, partially and temporarily, the effects of fatigue. Amphetamines enhance mental alertness and the ability to concentrate, and also cause wakefulness, euphoria, and talkativeness. Benzedrine is the trade name for the drug amphetamine; dextroamphetamine is marketed as Dexedrine. Methamphetamine, a potent stimulant marketed as Desoxyn, is the most rapidly acting amphetamine. They are available by prescription for limited uses; illegal sources include stolen or diverted supplies or clandestine laboratories.
Prescription amphetamines have been used for short periods of time in weight-control programs to suppress appetite and to treat narcolepsy. They were used as vasoconstrictors in inhalant therapy to shrink nasal mucous membranes in such conditions as nasal allergies and asthma; now such inhalants have been banned because of their toxicity. For unknown reasons, amphetamines have a paradoxically calming effect on some hyperactive children, but the use of these drugs to treat such children has been controversial.
Popularly known as bennies, crank, speed, pep pills, wakeups, or uppers, amphetamines are addictive and easily abused: users can become psychologically dependent on the drugs and, developing a tolerance for them, can require increasingly large doses (see drug addiction and drug abuse). When the drugs wear off, a long period of sleep ensues, often followed by hunger and depression, which can lead to further use of amphetamines. Amphetamine addiction has been common among such diverse groups as truck drivers, students, and athletes, who have used the drugs for increased energy, alertness, or endurance. Methamphetamine, made from ephedrine and other chemicals in clandestine laboratories in the the United States or Mexico, experienced a resurgence in use in the United States beginning the mid-1990s, and its abuse also has increased worldwide. Amphetamines are inhaled, taken orally, or injected; as with other injected drugs, needle sharing increases the risk of contracting the AIDS virus. One form of methamphetamine, "ice," is smoked. For law enforcement purposes in the United States, most amphetamines are grouped with such drugs as cocaine and morphine because of the similarity in their effects, medical usefulness, and high potential for abuse.
Amphetamines can produce severe systemic effects, including cardiac irregularities and gastric disturbances. Chronic use often results in insomnia, hyperactivity, irritability, and aggressive behavior. Addiction can result in psychosis or death from overexhaustion or cardiac arrest. Amphetamine-induced psychosis often mimics schizophrenia, with paranoia and hallucinations.