Characteristics of caffeine intoxication-related death in Tokyo, Japan, between 2008 and 2013.

Objectives: Caffeine is widely available in beverages and over-the-counter products; however, in large doses, it can lead to lethal arrhythmia. This study aims to clarify the characteristics of caffeine intoxication-related deaths in Tokyo, Japan.

Subjects: Among the 4754 forensic autopsy cases between 2008 and 2013 in which a toxicological investigation was performed, cases in which the blood concentration of caffeine exceeded toxic levels (15 μg/ml) were selected (N = 22). We examined subjects' ages, medical histories, direct/underlying causes of death, and manner of death. We also assessed concurrent drug substance detection and identified the origin of the caffeine.

Results: More than 60% of the subjects were between the ages of 20 and 49 years (n = 14, 63.6%). Sixteen cases (72.7%) showed a history of psychiatric diseases such as depression and sleep disorders. The underlying cause of death for all cases except two was caffeine intoxication, and manner of death was classified as undetermined (n = 11), accidental (n = 7), suicide (n = 2), or others (n = 2). Toxicological analysis revealed the presence of ingredients common to analgesics/cold remedies in 12 cases (54.5%). The origin of the caffeine was identified in 11 cases (50.0%); the proportion of identification was significantly lower among the cases in which analgesic/cold remedy ingredients were not detected (20.0%).

Conclusions: Caffeine intoxication-related deaths mainly occurred in young and middle-aged persons with common psychiatric diseases. Psychiatrists should take note of caffeine dependence while diagnosing common psychiatric symptoms. In half of the cases, the origin of the caffeine was unidentified; nevertheless, dietary sources or over-the-counter drugs containing caffeine were suspected. As it becomes easier to obtain caffeinated products, continuous monitoring of the number of deaths from caffeine intoxication, in addition to detailed investigations of the caffeine's origin, will be necessary.