Trends in poisonings involving ketamine in the United States, 2019-2023

Background: Off-label prescribing of ketamine to treat psychiatric disorders has been increasing, as has recreational use and availability of illicit ketamine. It is important to examine trends in ketamine-related poisonings to inform public health efforts.

Methods: We examined data from poisonings (exposures) involving ketamine reported to Poison Centers in the US between 2019 and 2023 (n = 1519). Annual trends were examined for number of exposures and characteristics of exposures, and we delineated correlates of major (life-threatening) adverse effects and death compared to less severe outcomes.

Results: The number of reported ketamine exposures increased from 205 in 2019 to 414 in 2023. Most cases involved ketamine ingestion (57.2 %), and a plurality involved misuse or "abuse" (36.2 %) and moderate effects (44.8 %). The percentage of cases involving suspected suicide attempts doubled from 12.7 % in 2019 to 25.9 % (a 103.9 % increase; P < 0.001); ingestion use increased from 46.0 % to 65.2 % (a 41.7 % increase; P < 0.001), and cases involving ketamine in liquid form decreased from 65.1 % to 41.2 % (a 36.7 % decrease; P < 0.001). Cases with major effects or death decreased from 23.4 % in 2019 to 15.6 % in 2023 (a 33.2 % decrease; P = 0.039). A major event or death was experienced by 18.6 % of cases, but prevalence was lower for those who inhaled ketamine (aPR=0.49, 95 % CI:0.29-0.85) compared to those who did not inhale.

Discussion: Poisonings involving ketamine are at their highest in reporting history. Both medical and recreational ketamine use and related adverse events need to be monitored, especially as off-label prescribing of take-home oral formulations appears to be increasing.