I found this little chart from the Erowid Vault.
Oral Caffeine Dosages
Threshold 10 - 20 mg
Common 50 - 150 mg
Strong 150 - 400 mg
Heavy 400 + mg
LD50 (Lethal Dose*) 192 mg/kg in rats
Onset : 5 - 10 minutes
Duration : 1.5 - 5 hours
Normal After Effects : up to 24 hours
* LD50 = dose which will kill 50% of the tested animals. It is estimated that fatal doses for humans are between 1 and 4 grams of caffeine, depending
on body weight and tolerance.
[edit on 11/12/2004 by Simulacra]



...i just don't need the caffeine i guess....i drink alot of water and juices and they satisfy my
thirst just fine...oops...other than a few beers every now and then 
