The consumption of caffeine, especially in the forms of coffee and tea, cola, chocolate, and cocoa, is ubiquitous in the United States. Other common sources of caffeine are over-the-counter analgesics, cold preparations, and stimulants. Although the existence of a caffeine withdrawal headache is well established, the syndrome is not severe enough to warrant clinical attention.
The essential features of this disorder are such characteristic effects of recent use of caffeine-containing substances such as restlessness, nervousness, excitement, insomnia, flushed face, diuresis, and gastrointestinal complaints. These symptoms appear in some people following ingestion of as little as 250mg of caffeine per day, while others may require much larger doses. At levels of more than 1g/day, there may be muscle twitching, rambling flow of thought and speech, cardiac arrhythmia, periods of inexhaustibility, and psychomotor agitation. Mild sensory disturbances such as ringing in the ears and flashes of light have been reported at higher doses. With doses exceeding 10g of caffeine, grand mal seizures and respiratory failure may result in death. This disorder has been called Caffeinism. A rough guide to calculating caffeine intake follows: coffee contains 100-150 mg of caffeine per cup; tea is about half as strong; a glass of cola is about a third as strong. Most caffeine-containing prescriptions and over-the-counter medications are one-third to one-half the strength of a cup of coffee. Two notable exceptions are migraine medications and over-the-counter stimulants that contain 100mg per tablet.
Complications include developing or aggravating gastrointestinal and heart disease. Caffeine can produce epigastric distress and, occasionally, peptic ulcer and hematemesis. In addition to arrhythmia with extremely high doses, the substance can cause marked hypotension and circulatory failure.
Manic episodes, Panic Disorder, and Generalized Anxiety Disorder can cause a clinical picture similar to that of Caffeine Intoxication. The temporal relationship of the symptoms to caffeine use establishes the diagnosis.