Characteristics of poisonings involving ketamine in the United States, 2019–2021

The use of ketamine, a controlled dissociative anesthetic, has become more widespread in recent years with recreational/nonmedical use increasing and ketamine becoming more widely available in clinics to treat depression. We examined recent trends in adverse effects related to ketamine use. US National Poison Control data were examined, focusing on ketamine exposures among those aged ⩾13 between 2019 and 2021 ( n = 758). We examined quarterly trends in exposure and delineated correlates of patients experiencing a major adverse effect or death. The number of reported exposures increased 81.1% from 2019 Quarter 1 through 2021 Quarter 4, from 37 to 67 ( p = 0.018). The majority of patients were male (57.1%), and the plurality of cases involved intentional misuse or “abuse” (39.5%), followed by suspected suicide attempt (19.7%) and unintentional exposure (18.9%). A fifth (19.6%) experienced a major adverse effect or death. A third (33.4%) co-used other drugs; the drugs most commonly co-used were benzodiazepines (14.6%), alcohol (10.3%), and opioids (8.7%). Co-use of gamma-hydroxybutyrate (GHB; adjusted prevalence ratio (aPR) = 3.43, 95% confidence interval (CI): 1.57–7.46) and opioids (aPR = 2.44, 95% CI: 1.46–4.08) was associated with increased risk for a major adverse effect or death, as was injection-only administration (aPR = 2.68, 95% CI: 1.21–5.92). Although still rare, poisonings involving ketamine have increased in recent years. Polydrug use—particularly with opioids or GHB—appears to be a particular risk factor for more serious adverse effects. As prevalence of use increases, it is important to monitor adverse effects and co-occurring behaviors to inform timely prevention and harm reduction as needed.