You can overdose on caffeine. 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. The symptoms of caffeine
intoxication may include restlessness, nervousness, excitement,
insomnia,increased urination, gastrointestinal
disturbance, muscle twitching, a rambling flow of thought and speech,
irritability, irregular or rapid heart beat .
