Coffee, tea, chocolate, coca cola and Anadin analgesic preparation, all of which contain caffeine. Caffeine is a stimulant found naturally in coffee beans, tea, cocoa beans and cola nuts. It is also added to other products such as analgesic preparations. Small amounts of caffeine reduce fatigue and stimulate the skeletal muscles, the heart and the kidneys. Excess can cause agitation and palpitations; continual use can result in dependence.