High-dose opioid administration is associated with significant adverse events. Evidence suggests that low-dose ketamine infusions improve perioperative analgesia over conventional opioid management, but usage is highly variable. Ketamine's adverse drug effects (ADEs) are well known, but their prevalence during low-dose infusions in a clinical setting and how often they lead to infusion discontinuation are unknown. The purposes of this study were 3-fold: (1) to identify patient factors associated with initiation of ketamine infusions during spine surgery, (2) to identify specific spine procedures in which ketamine has been used most frequently, and (3) to identify ADEs associated with postoperative ketamine infusions and which ADEs most frequently led to discontinuation. Spine surgery was chosen because of its association with moderate to severe pain and a relatively high use of ketamine infusions in this population at our hospital.