Excess drinking of coffee and tea may lead to addiction to caffeine as a stimulant, resulting in tension, headache, insomnia, racing heart and in severe cases, malnutrition through loss of appetite. Caffeine is used medically in tablet form as a stimulant, against headache and in certain cases for the treatment of asthma, but its abuse induces tolerance and mental dependence. Caffeine abuse, which is often coupled with nicotine abuse, may go unrecognized because coffee drinking is commonplace and socially acceptable; it is fully recognized as a drug problem.
According to a 1991 FDA report, the average American consumes 200 mg of caffeine (2-3 cups of coffee) per day.
Caffeine, while recognized as a drug, is beneficial in moderation. Even when the body builds tolerance, caffeine consumption elevates mood, decreases fatigue, enables hard work, stimulates clear thinking and in some cases wards off depression. Although caffeine withdrawal may cause headache and fatigue, such symptoms last only a few days. Some suggest caffeine is not a drug but a food-additive.