Ketamine has been found to help accelerate response to antidepressant treatment. In a four week-trail of participants who initiated a new antidepressants medication, half were randomly assigned to Ketamine infusion while the other half were assigned to placebo. The Ketamine infusion group created a quicker response time to treatment and did not suffer any noted side effects.

Ketamine has also been found to be a useful short-term treatment for suicidal ideation. Controlling for age, diagnosis, and other current therapies/medications, data from eight randomized trails suggest those who began Ketamine treatment noticed greater improvement within one day of treatment, and more patients (compared to controls) stopped experiencing suicidal ideation by day seven. While improvement began within the first day, the main effects were only noticed in the first week. While Ketamine infusion may not be a long-term solution for suicidal individuals, it can create a sense of relief and release that no other medication would be able to.

In a randomized clinical trial with individuals with major depressive disorder exhibiting significant suicidal ideation (N=80), Ketamine infusion therapy was compared with midazolam, a short-acting benzodiazepine anesthetic. Those individuals that received Ketamine exhibited a greater reduction in suicidal ideation within 24 hours.