Ketamine's clinical footprint has expanded substantially beyond treatment-resistant depression. The rapid-onset mechanism that addresses acute clinical needs — suicidality, PTSD with severe symptoms, certain chronic pain conditions, end-of-life psychological distress — distinguishes ketamine from conventional treatment in scenarios where waiting weeks for antidepressant effect is clinically inappropriate. The evidence base varies substantially across these indications; the discipline is to use ketamine where the evidence supports it and integrate it carefully with broader treatment.
The acute suicidality application is one of the most clinically compelling. A single ketamine infusion can reduce suicidal ideation within hours in patients with severe depression and active suicidality. The CTN-0035 trial and subsequent work have supported this application; the use in emergency departments and inpatient settings is increasing. The clinical role is bridging — rapid reduction in immediate suicidality while longer-acting treatment (medication adjustment, ECT, ongoing psychotherapy) takes effect. Ketamine in this scenario is a safety intervention, not a treatment endpoint.
PTSD evidence is meaningful but less mature. Several trials have shown rapid reduction in PTSD symptoms with ketamine treatment, though durability is more variable than in depression. The mechanism plausibility — memory reconsolidation effects, fear extinction support, rapid plasticity supporting trauma-focused therapy — fits the clinical picture. The Veterans Affairs system and some specialty PTSD programs have integrated ketamine into trauma treatment protocols. The integration with trauma-focused psychotherapy (prolonged exposure, EMDR, CPT) during the ketamine treatment window appears to enhance benefit beyond ketamine alone.
OCD has emerging evidence. Several small trials have shown rapid reduction in obsessive-compulsive symptoms following ketamine infusion. The mechanism may involve glutamatergic effects on the cortico-striato-thalamo-cortical circuit involved in OCD. The clinical use in OCD is less established than in depression, and the response is often shorter-lasting than in depression. The role in OCD is likely as augmentation to evidence-based treatment (SSRI plus ERP psychotherapy) when standard treatment has produced inadequate response.
Chronic pain applications cross between psychiatric and pain medicine. Complex regional pain syndrome (CRPS), neuropathic pain, fibromyalgia, and certain refractory chronic pain conditions have responded to ketamine infusion protocols, often higher-dose and longer-duration than psychiatric protocols. The overlap with psychiatric ketamine use is substantial — chronic pain frequently coexists with depression and anxiety, and the rapid relief in either domain may support broader treatment engagement. Coordination between psychiatry and pain medicine matters in patients receiving treatment for both.
End-of-life distress is an emerging application with strong rationale. Patients with advanced illness experiencing depression, anxiety, demoralization, or existential distress may benefit from rapid-onset relief that conventional treatment cannot deliver in the relevant timeframe. The evidence is still developing — smaller trials, often combined with psilocybin protocols where available — but the clinical scenario fits ketamine's profile well. Palliative care integration with ketamine-experienced clinicians is the developing pathway. The discipline is to recognize ketamine's expanded clinical footprint, use it where the evidence supports and where the alternatives are inadequate, and integrate it thoughtfully with the broader treatment plan in each scenario.