what category is caffeine in
Caffeine is a central nervous system (CNS) stimulant of the methylxanthine class of psychoactive drugs. It is the world's most widely consumed psychoactive drug, but unlike many other psychoactive substances, it is legal and unregulated in nearly all parts of the world.affeine is also a common ingredient of soft drinks, such as cola, originally prepared from kola nuts. Soft drinks typically contain 10 to 69 milligrams of caffeine per 12 ounce serving. By contrast, energy drinks, such as Red Bull, can start at 80 milligrams of caffeine per serving.