An acute overdose of caffeine, usually in excess of about 300 milligrams, dependent on body weight and level of caffeine tolerance, can result in a state of central nervous system over-stimulation called
caffeine intoxication,
[79] colloquially "caffeine jitters". The symptoms of caffeine intoxication are not unlike overdoses of other
stimulants. It may include restlessness,
nervousness, excitement, insomnia, flushing of the face,
increased urination,
gastrointestinal disturbance,
muscle twitching, a rambling flow of thought and speech, irritability,
irregular or
rapid heart beat, and
psychomotor agitation.
[77] In cases of much larger overdoses
mania,
depression, lapses in judgment,
disorientation, loss of social inhibition,
delusions,
hallucinations,
psychosis,
rhabdomyolysis, and
death may occur.
In cases of extreme overdose, death can result. The median lethal dose (
LD50) given orally, is 192 milligrams per kilogram in rats.
[1] The LD50 of caffeine in humans is dependent on weight and individual sensitivity and estimated to be about 150 to 200 milligrams per kilogram of body mass, roughly 80 to 100 cups of coffee for an average adult taken within a limited time frame that is dependent on
half-life. Though achieving lethal dose with caffeine would be exceptionally difficult with regular coffee, there have been reported deaths from overdosing on caffeine pills, with serious symptoms of overdose requiring hospitalization occurring from as little as 2 grams of caffeine.
[82][83][84][85] Death typically occurs due to
ventricular fibrillation brought about by effects of caffeine on the
cardiovascular system.