Caffeine is classified by the Food and Drug Administration as  generally recognized as safe  (GRAS). Toxic doses, over 10 grams per day for an adult, are much higher than typical dose of under 500 milligrams per day. A cup of coffee contains 80–175 mg of caffeine, depending on what bean (seed) is used and how it is prepared (e.g. drip, percolation, or espresso).