New analysis of multiple clinical trials finds intravenous ketamine can produce very fast relief from severe depressive symptoms and suicidal thinking, often within hours, while effects may fade and repeat treatments or close monitoring are usually required.
Ketamine started life as an anesthetic and has been repurposed in psychiatry because it can lift mood quickly when traditional antidepressants take weeks to work. Researchers pooled data from many trials and say a single infusion often eases depressive symptoms within hours and cuts suicidal thoughts sharply within a day. That speed is the headline advantage clinicians are watching closely.
The review covered dozens of studies and more than a thousand participants, with roughly half receiving ketamine and half serving as controls. Most people had major depressive disorder while a minority had bipolar-related depression. Across trials, the immediate mood benefits were clear, though the size and duration of benefit varied from study to study.
Compared with placebo, a single infusion often reduced depression in about four hours and dropped suicidal ideas within 24 hours. Patients reported fewer symptoms at one week and some retained reduced suicidal thinking for up to a month after one dose. Repeated infusions produced similar reductions by the end of multiweek treatment courses.
Side effects tended to be short lived and manageable for most patients, including headaches, numbness, dissociation, nausea, dizziness and visual disturbances that resolved within hours. More serious events such as hospitalization or suicide attempts were rare and frequently judged unrelated to the drug. Still, the review stresses careful monitoring because ketamine can have risks and some patients may misuse it.
“When all existing treatment options fail, patients with severe depression could consider ketamine infusions,” lead author Taeho Greg Rhee, PhD, of the University of Connecticut School of Medicine, said. He added that ketamine’s rapid action can be lifesaving in emergency settings for people who present with active suicidal thinking.
At the moment, intravenous ketamine is not FDA approved specifically for depression, but clinicians sometimes use it off label for severe or high-risk cases. “While intravenous ketamine is not yet FDA-approved for treating depression, it may still be used with off-label indications for those with severe depression and/or with a high risk of suicidal behaviors,” Rhee said. That unsettled regulatory status means patients and providers must weigh benefits, costs and follow-up plans carefully.
Psychiatrists with clinical experience with ketamine report dramatic, immediate relief for some patients who had exhausted other options. “For a small subset of patients in a major depressive episode or struggling with suicidal thoughts, intravenous ketamine can be genuinely lifesaving,” Bazzi, who has treated patients with infusions, said. She warns that infusions belong in supervised clinic settings, not informal or recreational environments.
The pattern seen across trials is familiar: rapid benefit that often fades, so many patients need repeated sessions to keep symptoms down. Clinics are experimenting with schedules to extend benefit while minimizing risk of dependence or adverse effects. Doctors also point out that some study participants may have known they received the drug, and that awareness can influence reported outcomes.
Limitations of the evidence include small sample sizes in many studies and differences in how trials were run, which complicates broad conclusions for the general population. Long-term outcomes remain under-studied, so the durability and safety of repeated infusions over months or years is not fully known. Still, when patients are at very high risk and other treatments have failed, ketamine often becomes a considered option.
“It should only be used medically,” he advised. Anyone thinking about ketamine treatment should discuss risks, realistic expectations and monitoring plans with a qualified clinician before pursuing infusions.
