If you were to ask a group of people sitting in a
             coffee shop what the most commonly used drug in America is, you
             might hear several answers. One person, thinking of illegal
             drugs might say cocaine. Another, thinking of medications, might
             say aspirin. A third person could identify alcohol or nicotine
             as the most commonly abused legal substance. They would all be
             wrong. Although it is not generally associated with the harmful
             effects of drug abuse, the most commonly taken drug in the United
             States, and possibly in the world, is caffeine.
             Caffeine is a common ingredient in beverages such as
             coffee, tea, soft drinks and cocoa. It is also in chocolate
             candy, chocolate ice cream, and other chocolate foods. Caffeine
             is even an ingredient in some common pain relievers. It could
             also, be obtained in tablet form without a prescription.
             Caffeine is a drug. A drug in any substance that changes how the
             body works. Caffeine has a stimulating effect on the brains and
             nerves, the heart and circulatory system, and the stomach and
             intestines. It also acts as a mild diuretic, which means that it
             helps increase urination and helps eliminate water from the body.
             Caffeine also has advantages and disadvantages. When taken in
             small to moderate amounts, caffeine can be harmless and even
             beneficial. It makes people feel more alert, helps them
             concentrate, and helps them work longer. It is used as an
             ingredient in some pain relievers because it has been shown to
             help relieve headaches. Caffeine is also found as an active
             ingredient in a variety of prescription drugs.
             Chemically, caffeine is one of a class of drugs called
             methylxanthines. It is odorless and has a slightly bitter taste
             in its pure form. As a drug, caffeine is considered a stimulant
             because it stimulates the central nervous system. It is also
             called a psychoactive drug because it can...