Caffeine, a methylxanthine CNS stimulant, raises safety concerns due to increasing access to tablets and concentrated anhydrous caffeine, which allow rapid ingestion of lethal doses. We report a fatal caffeine tablet overdose and review caffeine-related deaths examined at the National Forensic Service (NFS) from 2020 to 2025. Cases were analyzed according to year and age group. In the representative case, gastric contents, heart blood, and peripheral blood were analyzed by Gas chromatography-mass spectrometry(GC-MS) after liquid-liquid extraction(LLE). Twelve caffeine-related deaths were identified during the study period(2020-2025), with annual case counts of 1, 1, 2, 3, 1, and 4, respectively. Of these 11 (91.7%) involved individuals identified aged 10–39 years. One representative case was that of a woman in her 30s. Caffeine concentrations were 383 mg/L in heart blood and 376 mg/L in peripheral blood, within reported lethal ranges, with a large amount detected in gastric contents. Acute caffeine intoxication was determined as the cause of death. These findings underscore the need for public awareness of caffeine misuse among younger populations. The representative case illustrates how concentrated caffeine products can enable the rapid ingestion of fatal doses. Overall, these findings may provide baseline data to support forensic surveillance and public education regarding caffeine-related fatalities.