Caffeine is commonly used as a stimulant, and fatal
caffeine overdoses are increasing. In the present
study, two case reports showing a fatal blood concentration
of caffeine were reported and compared
to previously published case reports.
Case 1: A 19-year-old female was found dead in
her room. It was speculated that she ingested 84
tablets （100 mg） of a sleep-inhibitor product. The
caffeine levels in her cardiac blood and stomach
were 116 μg/ml and 619 μg/ml, respectively. There
was no macroscopic indication of any natural or unnatural
cause of death.
Case 2: The condition of a 47-year-old male deteriorated
suddenly. Hypothermia and excess sweating
were observed. After vomiting several times, he lost
consciousness. At autopsy, severe pulmonary edema
was observed. His cardiac blood caffeine level was
determined to be 171 μg/ml, which exceeds fatal
blood caffeine levels. However, there is no evidence
of his ingesting massive amounts of caffeine.
The blood caffeine concentration in previously
reported fatal caffeine ingestions ranged from 33 to
350 μg/ml. The two present cases are within this
range. The accumulation of data on blood caffeine
concentrations and ingestion amounts is helpful to
predict the intake amount of caffeine.