Objective: To review the pharmacology, pharmacokinetics, adverse effects, and drug interactions associated with caffeine and to raise awareness of the caffeine content of many prescription, nonprescription, and herbal drugs, beverages, and foods.
Data sources: Articles in English retrieved through a MEDLINE search (1966-August 2000) using the terms caffeine, human, and systemic. Additional product information was obtained from manufacturers' Web sites, through direct communications with manufacturers or distributors, and via Internet searches using the AltaVista search engine and the term caffeine. Only the first 10 Web sites selling caffeine products identified were visited.
Study selection: All articles and correspondence items from data sources were evaluated, and all information deemed relevant was included. Priority was given to information provided by manufacturers.
Conclusion: With the increase in consumers' use of over-the-counter products for health maintenance and self-care, it is imperative for pharmacists to be knowledgeable about the caffeine content of all drug and herbal products. It is important to be familiar with patients' self-treatment habits in order to identify potential caffeine-drug interactions or caffeine-laboratory interactions resulting in false laboratory values. These interactions increase health care costs by creating adverse effects and causing misdiagnoses.