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Ketamine: what the evidence shows

Available today through off-label prescribing. The effect is real; so is the relapse problem. Ketamine is an anaesthetic. For depression it is given at lower doses, usually as an infusion in a clinic. This page covers racemic ketamine; esketamine (Spravato) has its own page.

Not an approved treatment, but established off-label for treatment-resistant depression.

Last reviewed 23 October 2026Re-checked every month7 conditions with published evidence

Is ketamine legal where you live?See country-by-country rules on our Psychedelic Therapy Legality Map

Condition by condition

One card per condition, strongest evidence first. Hover or tap a label to see what it means; the numbers link to sources at the bottom of the page.

Treatment-resistant depression

Used off-label

Strong evidence for fast relief; keeping it going is the hard part.

The rapid antidepressant effect of a single low-dose infusion was first shown in a small placebo-controlled trial in 2006 and has been replicated many times since.12

In a 403-person trial, ketamine was at least as effective as electroconvulsive therapy (ECT) for treatment-resistant depression: 55% responded versus 41% with ECT.3

Relief often fades within days to weeks once infusions stop, and nobody has settled the best maintenance schedule yet.24

Racemic ketamine isn't licensed as an antidepressant, but it can be prescribed off-label; Norway, for example, now funds it in specialist care for treatment-resistant depression under set conditions.5

Compare every substance for treatment-resistant depression →

Alcohol use disorder

Late-stage trials · in progress

Positive Phase 2; a Phase 3 trial is recruiting in the UK.

In the UK KARE trial (96 people), ketamine infusions plus relapse-prevention therapy led to more days without alcohol over six months than placebo.6

MORE-KARE, a Phase 3 trial across NHS sites, is now testing this at scale. No results yet.7

Compare every substance for alcohol use disorder →

Cocaine & stimulant addiction

Early research

One encouraging randomised trial in cocaine use.

In a 55-person randomised trial, a single ketamine infusion plus mindfulness-based therapy kept 48% of people off cocaine in the final two weeks, versus 11% with an active placebo.8

Compare every substance for cocaine & stimulant addiction →

PTSD

Early research

One positive trial, one larger null result.

In a 30-person randomised trial, six infusions over two weeks reduced chronic PTSD symptoms more than an active placebo.9

A larger trial in 158 military personnel and veterans found no significant PTSD benefit over placebo.10

In a US clinic, 117 patients who got at least six infusions with preparation and integration sessions saw their PTSD scores drop by almost half. It's a look back at clinic records with no comparison group.11

Compare every substance for PTSD →

Suicidal thoughts

Early research

Fast, short-lived relief from suicidal thoughts. A bridge, not a cure.

Pooling individual data from 167 patients, one infusion reduced suicidal thoughts within a day, with effects lasting up to a week.12

In a 156-person randomised trial, 63% of inpatients on ketamine were free of suicidal thoughts on day 3, versus 32% on placebo. By six weeks the groups no longer differed.13

Compare every substance for suicidal thoughts →

Anxiety disorders

Early research

Short-lived effects in small studies.

Small studies in treatment-resistant generalised and social anxiety show quick relief that fades within days to a couple of weeks.1415

A systematic review found signals worth researching, but nothing near guideline-level evidence.16

Compare every substance for anxiety disorders →

OCD

Early research

Three small randomised trials, short-term effects.

A 2026 systematic review counted three small randomised trials: rapid anti-obsessional effects, but too little to judge lasting benefit, dosing or safety.17

The first crossover trial (15 adults) dates from 2013.18

A 2025 pilot in 12 people with treatment-resistant OCD found greater short-term improvement than an active control.19

Compare every substance for OCD →

Safety and who it's not for

Bladder and urinary damage (ketamine uropathy) is a recognised risk, best documented in heavy non-medical use; repeated medical use should include urinary checks.20

Experts flag misuse liability with repeated dosing, and long-term safety data are thin.4

Keep reading

Ketamine for Mental HealthHow ketamine works, the evidence for depression, PTSD and pain, safety, and how legal access works.Read the article The Promise of Ketamine Therapy: A Hope for Treatment-Resistant DepressionWhy ketamine can relieve treatment-resistant depression within hours, and how long it lasts.Read the article How Long Does Ketamine Work for Depression?How quickly ketamine acts on depression, and what decides how long the effect holds.Read the article Research databaseNew studies, summarisedHundreds of papers on psychedelics and mental health, each with a plain-language summary and key facts.Browse the database

Looking for care in Europe?

PsyAccess, our sister project, lists verified licensed providers and trial sites.

Sources

Numbered in the order they appear above. We only use peer-reviewed papers, official company announcements (for trial status and topline results), regulators and trial registries.

  1. Zarate CA et al. A randomized trial of an N-methyl-D-aspartate antagonist in treatment-resistant major depression. Arch Gen Psychiatry. 2006Journal
  2. Marcantoni WS et al. A systematic review and meta-analysis of the efficacy of intravenous ketamine infusion for treatment resistant depression. J Affect Disord. 2020Journal
  3. Anand A et al. Ketamine versus ECT for nonpsychotic treatment-resistant major depression. N Engl J Med. 2023Journal
  4. McIntyre RS et al. Synthesizing the evidence for ketamine and esketamine in treatment-resistant depression: an international expert opinion. Am J Psychiatry. 2021Journal
  5. Nye metoder / Beslutningsforum for nye metoder, Norway, 2025Regulator
  6. Grabski M et al. Adjunctive ketamine with relapse prevention-based psychological therapy in the treatment of alcohol use disorder. Am J Psychiatry. 2022Journal
  7. ISRCTN85955128, MORE-KARE, University of Exeter / NIHRTrial registry
  8. Dakwar E et al. A single ketamine infusion combined with mindfulness-based behavioral modification to treat cocaine dependence: a randomized clinical trial. Am J Psychiatry. 2019Journal
  9. Feder A et al. A randomized controlled trial of repeated ketamine administration for chronic PTSD. Am J Psychiatry. 2021Journal
  10. Abdallah CG et al. Ketamine treatment for PTSD in military personnel and veterans: a randomized clinical trial. Neuropsychopharmacology. 2022Journal
  11. MacConnel HA et al. Rapid and sustained reduction of treatment-resistant PTSD symptoms after intravenous ketamine in a real-world, psychedelic paradigm. J Psychopharmacol. 2025Journal
  12. Wilkinson ST et al. The effect of a single dose of intravenous ketamine on suicidal ideation: a systematic review and individual participant data meta-analysis. Am J Psychiatry. 2018Journal
  13. Abbar M et al. Ketamine for the acute treatment of severe suicidal ideation: double blind, randomised placebo controlled trial. BMJ. 2022Journal
  14. Glue P et al. Ketamine's dose-related effects on anxiety symptoms in patients with treatment refractory anxiety disorders. J Psychopharmacol. 2017Journal
  15. Taylor JH et al. Ketamine for social anxiety disorder: a randomized, placebo-controlled crossover trial. Neuropsychopharmacology. 2018Journal
  16. Whittaker E et al. Systematic review of ketamine in anxiety disorders. 2021Journal
  17. Heroiu et al. Ketamine in obsessive-compulsive disorder: a systematic review. 2026Journal
  18. Rodriguez CI et al. Randomized controlled crossover trial of ketamine in obsessive-compulsive disorder. Neuropsychopharmacology. 2013Journal
  19. Beaglehole B et al. Ketamine versus active control in treatment-resistant OCD: randomised pilot trial. 2025Journal
  20. British Association of Urological Surgeons consensus statement on ketamine uropathy. BJU Int. 2024Journal