The most common withdrawal symptom is a throbbing and/or pressure headache, usually located at the temples but occasionally at the back of the head or around the eyes. A vague muscular headache often follows. Of course, caffeine cures the symptom; but this is not the answer. Dietary guidelines and supplements may help with this and other withdrawal problems.

Let us now look at the wide range of uses of caffeine in the food and drug industries. Caffeine and caffeinelike xanthines are contained in coffee, many teas, cola, and chocolate. Of the teas, all "black" teas or common teas contain theophylline and theobromine, as do some "green" teas. Both contain less caffeine than coffee. These teas and coffee also contain tannic acid, which is a mild irritant to the gastrointestinal mucosa, and may further bind and reduce absorption of minerals, such as manganese, zinc, and copper. Most herbs do not contain caffeine, although maté and guarana are fairly high in caffeine. The kola nut and the cocoa bean also contain caffeine. All of these are natural products that have been used as stimulants throughout history; today, caffeine and its related stimulating xanthines are used in many artificial products, including soft drinks such as Coca-Cola, Pepsi Cola, Mountain Dew, Dr. Pepper, and Jolt, plus many chocolate bars. (Some of the soft drink companies are now making caffeine-free drinks.)