A stimulant drug is a class of drugs that increase the activity of the central nervous system, leading to heightened alertness, energy, and sometimes feelings of euphoria. Stimulants work by speeding up messages between the brain and body, increasing heart rate, blood pressure, and respiration, and enhancing focus, mood, and physical performance. Common examples include caffeine, nicotine, amphetamines, cocaine, and prescription medications like methylphenidate. They are used both medically (e.g., for ADHD, narcolepsy) and recreationally, but they carry risks such as addiction, tolerance, and various health problems.
