Stimulants include a wide variety of substances that reverse the effects of fatigue. Drugs that fall in this category include a number of common substances that are used by many people every day, including caffeine, the active ingredient in soft drinks, tea and coffee, and nicotine, the active ingredient in tobacco, as well as many controlled substances, such as cocaine and amphetamines.
Stimulants are prescribed by physicians to treat obesity, narcolepsy and attention deficit hyperactivity disorder. As drugs of abuse, stimulants are used to increase activity, reduce appetite, improve mental and physical performance, and "get high." However, the "high" is typically followed by a "crash" characterized by depression, anxiety, cravings for more of the drug and extreme fatigue. Physical side effects of stimulant use include headaches, dizziness, tremors, chest pain with palpitations, excessive sweating, vomiting and cramping. In addition, psychological effects include hostility, agitation, panic, aggression, paranoia, and suicidal or homicidal tendencies.
Stimulants are highly addictive, both physically and psychologically. In addition, tolerance can develop rapidly with these drugs. Death can occur from stimulant use as the drugs interfere with the body's cardiovascular and temperature-regulating systems.