Organic compound, prototype of a class of synthetic amphetamine drugs (e.g., Benzedrine, Dexedrine, methamphetamine), that stimulates the central nervous system. It was first synthesized in 1887. Amphetamines cause wakefulness, euphoria, decreased fatigue, and increased ability to concentrate. Since they dull the appetite, they have been used for weight reduction. Often called speed, they are used (often illicitly) to stay awake. In children with attention deficit (hyperactivity) disorder, they have a calming effect, helping them concentrate. Undesirable effects include overstimulation, with paranoia, restlessness, insomnia, tremor, and irritability, and a deep depression when the drug wears off. This, along with rapid development of tolerance requiring increased doses, can lead to drug addiction.