Q & A
Published: January 24, 2011
Q. Can too much caffeine kill you?
A. In very rare cases, overdoses of caffeine have been fatal. The estimated fatal oral dose, which varies because of factors like weight, is 5 grams to 10 grams.
It would be very hard, probably impossible, to ingest enough caffeine to kill yourself by drinking ordinary coffee. According to government estimates, an eight-ounce cup of brewed coffee contains 60 to 120 milligrams of caffeine. Assuming a caffeine content on the high side and a fatal dose on the low side, you would have to drink at least 42 cups at a sitting.
But caffeine is found in higher amounts in energy drinks, medications and herbal preparations.
Concentrations of caffeine in blood plasma that are higher than 15 milligrams per liter of blood can cause toxic reactions, and caffeine overdoses are a relatively common cause of poisoning emergencies, with 4,183 such cases reported by the American Association of Poison Control Centers in 2007.Only one death occurred among those cases.