We consume caffeine in coffee, tea, cocoa, chocolate, some soft drinks, and some drugs. The actual source of caffeine is the coffee bean, tea leaf, kola nut and cacao pod.
Pure caffeine is odorless and has a bitter taste.
Effects of Caffeine on the Nervous System Caffeine is classified as a central nervous system stimulant . In massive doses, caffeine is lethal. Caffeine enters the bloodstream through the stomach and small intestine and can have its effects as soon as 15 minutes after it is consumed. Once in the body, caffeine will stay around for hours - it takes about 6 hours for one half of the caffeine to be eliminated. Caffeine belongs to the xanthine chemical group.