# Effects of Intravenous Ketamine on Posttraumatic Stress Disorder (PTSD): A Systematic Review

## TL;DR

This review finds that intravenous ketamine may help reduce PTSD symptoms, but more research is needed to understand how it works and its long-term effects.

## Contribution

The study systematically evaluates the clinical outcomes and potential mechanisms of ketamine for PTSD treatment.

## Key findings

- Ketamine improved PTSD symptoms as measured by CAPS-5 and IES-R in some trials.
- Repeated lower doses of ketamine were more effective than standard single doses.
- Amygdala inhibition by the vmPFC may be linked to symptom improvement in PTSD patients.

## Abstract

Posttraumatic stress disorder (PTSD) is a mental disorder resulting from exposure to traumatic events. Evidence suggests that ketamine may be efficacious in treating PTSD, however, ketamine's mechanisms in treating PTSD remain unclear. Herein, this review aims to evaluate the clinical outcomes of ketamine treatment in persons with PTSD and investigate the possible neurobiological mechanisms underlying ketamine's therapeutic effect in PTSD.

A systematic search was conducted on PubMed and OVID (MEDLINE, Embase, PsychINFO) from inception until September 2025. Randomized controlled trials reporting on the effects of intravenous ketamine to treat PTSD were included.

Seven studies with a total of 323 participants were included in this review. Ketamine administration meaningfully improved PTSD symptoms in two trials as evidenced by significant improvement on the Clinician‐Administered PTSD Scale for DSM‐5 (CAPS‐5) and the Impact of Event Scale‐Revised (IES‐R) compared to control/placebo. Multi‐infusion administration schedules achieved greater clinical outcomes when compared to single‐dose administration schedules. Preliminary evidence suggests that repeated lower doses (0.2mg/kg) of ketamine were more efficacious in sustaining treatment effects than standard doses (0.5mg/kg). For persons receiving ketamine, an association was observed between top‐down inhibition of the amygdala originating in the ventromedial prefrontal cortex (vmPFC) and symptom improvement.

Our results suggest that intravenous ketamine may be efficacious in the treatment of PTSD. Subsequent studies should attempt to evaluate the additive effect of combining ketamine with psychotherapeutic interventions as well as determining mechanistic pathways mediating symptom relief in persons with PTSD.

Summations○Intravenous ketamine administered in certain treatment regimens may be efficacious in the treatment of adults with PTSD.○Ketamine's mechanisms in treating PTSD remain unclear and require further investigation.
Limitations○The methodologies of extant randomized controlled trials which evaluate ketamine in PTSD vary significantly.○The absence of available literature precluded analysis of ketamine's long‐term treatment effects for PTSD.

Summations○Intravenous ketamine administered in certain treatment regimens may be efficacious in the treatment of adults with PTSD.○Ketamine's mechanisms in treating PTSD remain unclear and require further investigation.

Intravenous ketamine administered in certain treatment regimens may be efficacious in the treatment of adults with PTSD.

Ketamine's mechanisms in treating PTSD remain unclear and require further investigation.

Limitations○The methodologies of extant randomized controlled trials which evaluate ketamine in PTSD vary significantly.○The absence of available literature precluded analysis of ketamine's long‐term treatment effects for PTSD.

The methodologies of extant randomized controlled trials which evaluate ketamine in PTSD vary significantly.

The absence of available literature precluded analysis of ketamine's long‐term treatment effects for PTSD.