Caffeine, a white bitter substance found in coffee, tea, and chocolate,
is the world's most widely used drug. It is also found in some cough and
cold remedies, soft drinks and even aspirin. High doses of caffeine may
cause nausea, trembling, headache and nervousness. Scientists have found
that people who stop using caffeine have withdrawl symptoms that include
mood changes and headaches. Caffeine is a drug that can cause serious damage.