The
LD-50 of caffeine (that is the lethal dosage reported to kill 50% of the population) is estimated at 10
grams for
oral intake.
As it is usually the case,
lethal dosage varies from individual to individual according to
weight.
Ingestion of 150mg/kg of caffeine seems to be the average LD-50 for people. That is, people weighting 50
kilos have an LD-50 of about 7.5 grams, people weighing 80 kilos have an LD-50 of about 12 grams.
On one occasion it was reported that a man
survived after
ingesting 24 grams.
The minimum lethal dose ever reported was 3.2 grams taken
intravenously (injected).
Acute caffeine
poisoning gives early symptoms of
anorexia,
tremor, and
restlessness. Followed by
nausea,
vomiting, and
confusion. Serious intoxication may cause
delirium,
seizures, and
hyperglycemia. Super high dose caffeine intake can lead to
nervousness,
irritability,
anxiety,
muscle twitching,
insomnia,
palpitations and
hyperreflexia.
-Information from Desk Reference to the Diagnostic Criteria from DSM-3-R (
American Psychiatric Association,
1987)