Amphetamine is a synthetic drug. The drug is a stimulant: it can help people keep the focus and stay awake. It also decreases appetite and fatigue. Chemically, it is similar to methamphetamine. These drugs increase the level of dopamine and norepinephrine in the brain, which can create euphoria. The class of drugs containing amphetamine includes prescription drugs commonly used to treat attention-deficit hyperactivity disorder (ADHD). It is also used to treat symptoms of traumatic brain injury (TBI) and the daytime drowsiness symptoms of narcolepsy, amongst others. Initially, amphetamine was more popularly used to reduce appetite and to control weight.