What Is Caffeine?:
Caffeine is a naturally occurring substance, first isolated from coffee. It is present in a number of other plants, which means it also finds its way into a number of common foods and drinks. It is considered a psychoactive stimulant drug -- a substance that affects the central nervous system, causing an increase in alertness and awareness.What Foods and Drinks Contain the Most Caffeine?:
Caffeine is a component of many foods and beverages, notably coffee and tea. It is added to many soft drinks and sports/energy drinks as well. Chocolate is another source of caffeine, although the stimulant is usually in lower concentrations than what's found in coffee, espresso, and tea.How Do Caffeine and Headaches Relate Exactly?:
If you consume caffeine on a regular basis and then attempt to eliminate it from your diet, you are in danger of developing caffeine withdrawal. One of the symptoms of withdrawal is headache. A caffeine withdrawal headache may come in many forms, but it is commonly described as coming on slowly, affecting the entire head, and throbbing. Severity varies from person to person, but caffeine withdrawal headaches can be quite painful.Why Some Headache Remedies Contain Caffeine:
There is some evidence to suggest that small doses of caffeine may actually increase the absorption of other medicines, making them a bit more effective in treating headaches. Excedrin and Fioricet are two headache relievers that contain caffeine.What Should I Do If I Get Caffeine Withdrawal Symptoms?:
Along with headaches, other symptoms of caffeine withdrawal include fatigue, sleepiness or drowsiness, difficulty concentrating, irritability, depression or anxiety, and flu-like symptoms. If you suspect that symptoms such as these are being caused by caffeine withdrawal, be sure to contact your healthcare provider. If you feel you need to cut back on caffeine in your diet, he or she can help you do so in a safe manner so as to reduce the chance of developing headaches and other troublesome symptoms. Source:
Graham A.W., Schultz T.K., Mayo-Smith M.F., Ries R.K. & Wilford, B.B. (eds.) Caffeine pharmacology and clinical effects. Principles of Addiction Medicine, Third Edition (pp. 193-224). Chevy Chase, MD: American Society of Addiction)

