Coastwise Health Blog
Updated May 23, 2026
Written by the Coastwise Clinical Team
Ketamine is one of the most studied medications in psychiatry, and one of the most poorly understood by the general public. The medication has been used in surgical and emergency anesthesia since the 1970s and in psychiatric research since the late 1990s. The first randomized controlled trial showing rapid antidepressant effects was published in 2000. Since then, hundreds of studies have examined ketamine for depression, suicidality, PTSD, and anxiety, with FDA approval of an esketamine formulation (Spravato) coming in 2019.
This post walks through what the research actually shows: the foundational studies, the strongest evidence base (suicidality and treatment-resistant depression), the PTSD trials, the more limited anxiety literature, and what the research does not yet show.
The story of ketamine in psychiatry starts at Yale in the late 1990s. Researchers were investigating the role of the brain's glutamate system in depression. They tested a sub-anesthetic dose of ketamine, which blocks NMDA receptors and modulates glutamate, in seven patients with depression.
Berman and colleagues published the result in 2000 in Biological Psychiatry: rapid and clinically significant reduction in depressive symptoms within hours, lasting up to 72 hours. This was a striking finding because every existing antidepressant took weeks to work. Berman's paper was small but it changed the trajectory of depression research.
Six years later, Zarate's team at NIH published the first randomized controlled trial in Archives of General Psychiatry (2006). The study enrolled patients with treatment-resistant depression and showed that a single intravenous infusion of ketamine produced rapid antidepressant effects within 2 hours, with benefits lasting up to 7 days. This trial established the modern paradigm: ketamine works fast, often when nothing else has, and through a different mechanism than SSRIs.
Krystal and colleagues described the implications of this in Neuron in 2019. The fact that a single dose produces rapid effects suggested depression involves something more than serotonin, the dominant theory for 30-plus years, and that targeting the glutamate system opened up a new class of treatments. Spravato (esketamine), FDA-approved in 2019, came out of this line of research.
Treatment-resistant depression (TRD) is depression that has not responded to at least two adequate trials of standard antidepressants. By some estimates, roughly one-third of patients with major depression meet this criterion. For these patients, the conventional toolkit has run out.
Ketamine has the strongest evidence base in this population. Multiple meta-analyses since Zarate 2006 have confirmed rapid and clinically meaningful reductions in depressive symptoms in TRD with both racemic ketamine (off-label, IV or IM) and esketamine (FDA-approved, intranasal). Response rates in clinical trials are typically in the 50 to 70 percent range, which is substantially higher than what's achieved with another SSRI trial in this population.
What the research clearly supports for TRD: rapid relief, clinically meaningful improvement, comparable safety to other treatments when delivered with appropriate clinical monitoring.
What the research is still working out for TRD: optimal dosing schedules for sustained response, who responds best, and how to integrate ketamine with ongoing psychotherapy and medication.
One of the most consistent findings in the ketamine literature is the rapid reduction of suicidal ideation. The clinical implication is significant: suicidal ideation is a medical emergency, and existing antidepressants take weeks to work, leaving a high-risk window where the patient is at acute risk while waiting for medication to take effect.
Wilkinson and colleagues published an individual participant data meta-analysis in the American Journal of Psychiatry in 2018, pooling data from multiple RCTs of single-dose intravenous ketamine. A single ketamine infusion produced clinically significant reduction in suicidal ideation within 24 hours, with effects lasting several days. The effect was independent of the broader antidepressant effect, meaning ketamine reduces suicidal thoughts even in patients whose overall depression score doesn't fully respond.
This finding has reshaped acute psychiatric care in some settings. Some emergency departments and crisis services now use ketamine for high-risk presentations, with the goal of bridging the patient to longer-term treatment.
The PTSD evidence base is solid and growing. Feder's 2014 RCT in JAMA Psychiatry was the first randomized controlled trial showing that a single dose of IV ketamine produced clinically meaningful reduction in chronic PTSD symptoms within 24 hours. The effect was independent of the antidepressant effect, meaning ketamine appeared to be doing something specific to PTSD symptoms, including intrusive memories, hyperarousal, and avoidance, rather than just lifting overall mood.
Feder's follow-up trial in 2021, published in the American Journal of Psychiatry, looked at repeated dosing. Patients with chronic PTSD received six infusions over two weeks and showed sustained improvement compared to placebo. This is meaningful because PTSD often doesn't respond to SSRIs, and adding a treatment with a different mechanism opens real options for clients who have been stuck.
For trauma-driven substance use, which is a common dual diagnosis pattern, the implications are practical. Many clients have a primary trauma history that drives their use, and standard antidepressants don't fully address it. Ketamine paired with trauma-focused therapy is increasingly used for this combination.
The evidence base for anxiety disorders is more limited than depression or PTSD, but it's growing. Smaller trials and open-label studies have shown ketamine produces rapid reduction in generalized anxiety, social anxiety, and OCD symptoms in some clients. Mechanism research suggests the same glutamate modulation that helps with depression and PTSD is relevant to anxiety as well.
What the field doesn't yet have for anxiety: large multi-site RCTs comparable to the depression and PTSD literature. Clinical use for anxiety is generally based on extension from the broader evidence and individual response.
Most of the foundational ketamine research used IV infusions delivered without psychotherapy. The KAP model, pairing ketamine with structured psychotherapy, is newer, and the formal RCT evidence is still developing.
Dore and colleagues published a retrospective analysis in the Journal of Psychoactive Drugs in 2019, looking at outcomes from three KAP practices treating over 200 clients with depression and anxiety. The data showed clinically meaningful improvement in symptoms, with KAP appearing to extend the duration of benefit compared to ketamine alone. The mechanism is intuitive: ketamine creates a window of cognitive flexibility, and psychotherapy uses that window to support new patterns.
What the KAP-specific research supports: clients with depression, anxiety, and trauma who participate in structured KAP show clinically meaningful improvement, often with longer duration of benefit than ketamine-only protocols. What it doesn't yet show in large RCTs: the precise added value of psychotherapy versus ketamine alone, or the optimal psychotherapy modality to pair with ketamine. Those studies are in progress.
Several open questions remain:
The honest position: the evidence supports ketamine as a meaningful clinical option for treatment-resistant depression, acute suicidality, and chronic PTSD. It does not yet support ketamine as a first-line treatment for everyone with these conditions, and it does not have the same long-term safety record as SSRIs, which have 30-plus years of post-market data.
At Coastwise, our KAP program is built around what the research supports:
If your situation calls for IV infusion, we coordinate with infusion partners in Los Angeles and continue therapy support around those sessions.
Therapy sessions in clinical KAP are covered by most major insurance plans. The medication itself is often out of pocket. Spravato (FDA-approved esketamine) is covered with prior authorization for treatment-resistant depression. Our admissions team verifies what your specific plan covers. Call (424) 536-3002 or verify online.
If you're trying to decide whether ketamine therapy fits your situation, a free consultation with our admissions team can help. We'll go through your treatment history, what you've tried, what your insurance covers, and whether KAP looks like a fit. If it isn't, we'll tell you that.
Call (424) 536-3002 or request a consultation online. Monday through Saturday, 9:00 AM to 8:00 PM.
Located at 1366 W 7th Street, San Pedro, CA.
The first randomized controlled trial of ketamine for depression was published by Berman in 2000 in Biological Psychiatry. Zarate's 2006 RCT in Archives of General Psychiatry showed rapid antidepressant effects in treatment-resistant depression. Multiple meta-analyses since have shown ketamine produces clinically meaningful reductions in depressive symptoms within hours to days, especially for treatment-resistant cases. The FDA approved esketamine (Spravato) in 2019 specifically for treatment-resistant depression.
Yes. Wilkinson's 2018 individual participant data meta-analysis in the American Journal of Psychiatry pooled data from multiple RCTs and found that a single dose of intravenous ketamine produces rapid (within 24 hours) and clinically significant reduction in suicidal ideation, with effects that often last several days. This is one of the strongest evidence bases for ketamine's clinical use in acute psychiatric crisis.
Yes. Feder's 2014 RCT in JAMA Psychiatry was the first controlled trial showing ketamine produces clinically meaningful reduction in chronic PTSD symptoms within 24 hours of a single dose. Feder's 2021 follow-up trial in the American Journal of Psychiatry showed that repeated infusions produced sustained improvement over a 2-week course. PTSD evidence for ketamine is now well-established, though more limited than the depression literature.
Dore's 2019 retrospective analysis in the Journal of Psychoactive Drugs reported on outcomes from three ketamine-assisted psychotherapy practices treating over 200 clients. The data showed clinically meaningful improvement in depression and anxiety symptoms, with KAP appearing to extend the duration of benefit compared to ketamine alone. KAP-specific RCTs are still emerging, but the clinical outcomes data is consistent with the medication-only research.
Several open questions remain. Long-term outcomes beyond 12 months are less well-studied. Optimal dosing schedules for sustained benefit are not standardized. Predictors of who responds versus who doesn't are not fully understood. The relative advantage of ketamine plus psychotherapy (KAP) versus ketamine alone is supported by clinical experience and observational data but not yet by large RCTs. Anxiety disorder evidence is more limited than depression and PTSD evidence.
Esketamine (Spravato) is FDA-approved for treatment-resistant depression. It was approved in 2019 as the first new mechanism for depression in over 30 years. Racemic ketamine is not FDA-approved for psychiatric conditions and is used off-label in clinical practice, which is legal and clinically well-established.
The first call is free, confidential, and without pressure. We'll help you figure out whether KAP fits, and if not, we'll point you somewhere that does.
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