Caffeine is a naturally occurring xanthine derivative.
Other xanthine derivatives include the bronchodilator theophylline and theobromine, a compound found in cocoa and chocolate. Caffeine is found in many beverages and soft drinks. Clinically, it is used parenterally as a respiratory stimulant in neonates. It also is sold without a prescription in products marketed to treat drowsiness. Caffeine was first approved by the FDA for use in a drug product in 1938.