Amphetamines are a group of synthetic psychoactive drugs called central nervous system (CNS) stimulants. Medications containing amphetamines are prescribed for narcolepsy, obesity, and attention deficit-hyperactivity disorder.

When amphetamine was first synthesized in 1887, by the German chemist L. Edeleano, the stimulant effects were not noticed. In the early 1930s, when amphetamine's CNS stimulant properties and use as a respiratory stimulant were discovered it was marketed as an inhaler for nasal congestion (Benzedrine©). 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. Now such inhalants have been banned because of their toxicity but are still available by prescription for limited uses.

Amphetamines may produce acute systemic effects, which includes cardiac irregularities and gastric disturbances. Chronic use frequently results in insomnia, hyperactivity, irritability, and aggressive behavior.

Abuse of amphetamine began rising during the 1960s and 1970s with the discovery that the intravenous injection of amphetamines (particularly methamphetamine) produced enhanced euphoric effects with a more rapid onset than oral administration. Amphetamine is also popular with athletes in training because of the enhanced performance consequent on increased cardiac output.