Safety and tolerance of oral ketamine: A systematic review.
Nathalia Novaretti, Rebeca Mendes P Pessoa, Jaime Eduardo Cecilio Hallak, Rafael Guimarães Dos Santos, Marcos Hortes N Chagas
Psychiatry and Clinical Neurosciences May 30, 2026 DOI: 10.1111/pcn.70091 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Systematic review Randomized Placebo-controlled Peer reviewed |
|---|---|
| Sample size | 427 |
| Population | Adults, children, and healthy volunteers |
| Intervention | oral ketamine |
| Topics | Ketamine Esketamine |
| Keywords | Oral administration Adverse effects Safety Tolerability |
| Key findings | Oral ketamine demonstrates a favorable short-term safety profile, though the certainty of evidence is low and long-term safety remains uncertain. |
Abstract
Oral ketamine has gained increasing interest beyond anesthesia, particularly for treatment-resistant depression, chronic pain, and pediatric procedural sedation. Despite expanding off-label use, there is no standardized pharmaceutical formulation, and long-term safety remains uncertain. A synthesis of evidence on safety and tolerability of the oral route is therefore needed to inform clinical practice and regulatory development. This systematic review evaluated the safety and tolerability profile of oral ketamine in humans and characterized dosing strategies across randomized controlled trials. A systematic search was conducted in PubMed, Embase, Scopus, and Web of Science from inception to November 2025 (PROSPERO CRD420251065295). Randomized placebo-controlled trials evaluating oral (es)ketamine in any clinical population were included. Primary outcomes were safety and tolerability. Risk of bias was assessed using the RoB2 tool, and certainty of evidence was evaluated using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) framework. Eighteen trials were included, comprising adults, children, and healthy volunteers. In depression studies (n = 5; 427 participants), adverse effects were predominantly mild and transient. Pediatric premedication trials (n = 239) reported transient neurological effects without clinically significant safety concerns. Pain and experimental studies (n = 372) showed mostly mild adverse events, with dissociative symptoms at higher doses. Comparative analyses indicated higher rates of dizziness, sedation, and dissociative symptoms with ketamine, while serious adverse events were rare. Overall, oral ketamine demonstrates a favorable short-term safety profile. However, the certainty of evidence is low, and long-term safety remains uncertain.
Comparable studies
Other systematic reviews and meta-analyses on ketamine, most cited first.
| Study | Year | Design | Participants |
|---|---|---|---|
| The effect of a single dose of intravenous ketamine on suicidal ideation: a systematic review and individual participant data meta-analysis Depressed patients with suicidal ideation at baseline | 2017 | Systematic review and individual participant data meta-analysis | n = 167 |
| Ketamine use: a review Ketamine users | 2011 | Systematic review | |
| Ketamine and Other NMDA Antagonists: Early Clinical Trials and Possible Mechanisms in Depression Participants with major depression in placebo-controlled, double-blind, randomized... | 2015 | Systematic review and meta-analysis | |
| Ketamine and postoperative pain – a quantitative systematic review of randomised trials Surgical patients from 25 countries | 2004 | Systematic review | n = 2,839 |
| Side-effects associated with ketamine use in depression: a systematic review. Patients with depression | 2018 | Systematic review |
Citations in the library
Cites 16
- Efficacy of Esketamine Nasal Spray Plus Oral Antidepressant Treatment for Relapse Prevention in Patients With Treatment-Resistant Depression JAMA Psychiatry June 5, 2019
- A Consensus Statement on the Use of Ketamine in the Treatment of Mood Disorders JAMA Psychiatry March 1, 2017
- Side-effects associated with ketamine use in depression: a systematic review. The Lancet Psychiatry 2018
- Comparative efficacy of racemic ketamine and esketamine for depression: a systematic review and meta-analysis Journal of Affective Disorders September 23, 2020
- The effect of intravenous, intranasal, and oral ketamine in mood disorders: A meta-analysis. Journal of Affective Disorders November 1, 2020
and 11 more in the library