Rates and Clinical Characteristics of Self-Administered Fatal Ketamine-Related Poisoning in Australia, 2000-2025

Recent years have seen marked increases in the non-medical use of ketamine. We aimed to determine: (i) the population mortality rates of self-administered fatal ketamine-related poisoning cases in Australia, 2000-2022; (ii) the characteristics, toxicology and major autopsy findings of cases in Australia, 2000-2025; and (iii) changes in case characteristics across the period 2000-2025.

Retrospective study of fatal ketamine-related poisoning in Australia retrieved from the National Coronial Information System.

118 cases were identified, 100 (84.7%) of which occurred after 2014. There was a significant upward trend in event rates between 2000 and 2022 (IRR = 1.16). The mean age was 36.2 years and 77.1% were male. The majority (72.9%) of poisonings were unintentional, in 19.5% the final route of ketamine administration was by injection, and a history of substance use problems was documented in 50.8%. There were no significant differences in these case characteristics across the study period. In 14 cases, the decedent was documented as being prescribed take-home ketamine at the time of death and had consumed this medication. The median blood ketamine concentration was 0.20 mg/L (range 0.01-25.0), which did not significantly differ across time. Psychoactive drugs other than ketamine were present in all cases, most frequently hypnosedatives (68.6%) and opioids (62.7%), with a significant difference across time observed in the presence of hypnosedatives (OR 1.45). Cardiomegaly was diagnosed in 13.9% and cardiac fibrosis in 11.1%.

There has been a significant increase in self-administered ketamine-related poisoning deaths. Caution should be exercised in prescribing ketamine for self-administration.