Low-Dose Ketamine for Treatment-Resistant Depression

Low dose ketamine depression treatment may provide rapid, short-term symptom relief for some adults with treatment-resistant depression, but it requires careful clinical assessment and monitoring. Treatment-resistant depression usually means depression that has not improved enough after adequate antidepressant treatment attempts. Intravenous racemic ketamine is commonly used off label in this setting, while intranasal esketamine, marketed as Spravato, is FDA approved for treatment-resistant depression when used with an oral antidepressant.

Ketamine is not a replacement for emergency care. A person in immediate danger or considering self-harm should call or text 988 in the United States, contact local emergency services, or go to the nearest emergency department.

What treatment-resistant depression means

Treatment-resistant depression, or TRD, is major depressive disorder that has not responded adequately to prior treatment. Definitions vary across studies and clinical settings, but failure to improve after two adequate antidepressant trials is a common threshold used in research and practice.

TRD can be difficult to manage because symptoms may persist despite medication, psychotherapy, or both. The National Institute of Mental Health describes depression as a condition that can interfere with daily functioning and may require a combination of treatments. If standard approaches have not helped enough, a psychiatric clinician can review whether prior trials were adequate and discuss next steps. Our guide to treatment-resistant depression next steps outlines questions that can help structure that review.

How ketamine may work in depression

Ketamine is an anesthetic medicine that affects glutamate signaling, including N-methyl-D-aspartate, or NMDA, receptors. At subanesthetic doses, researchers think its effects may involve changes in glutamate activity and downstream pathways related to synaptic plasticity. Synaptic plasticity is the brain's ability to change the strength and organization of connections between nerve cells.

Mechanisms remain an active area of research. Laboratory and animal findings involving AMPA receptors, brain-derived neurotrophic factor, or BDNF, and mechanistic target of rapamycin, or mTOR, help explain possible pathways, but they do not by themselves predict how any individual patient will respond. Read more about the proposed biology in neuroplasticity and ketamine.

What clinical studies show

Clinical trials have found that ketamine can improve depressive symptoms rapidly for some people with major depressive episodes, including people with TRD. In a 2006 randomized, placebo-controlled study, Zarate and colleagues reported a rapid antidepressant effect after a single 0.5 mg/kg intravenous ketamine infusion in patients with treatment-resistant major depression. The study was small, and its results should be interpreted alongside later trials and reviews.

According to a 2021 systematic review and meta-analysis published in The Lancet Psychiatry, ketamine was associated with greater short-term response and remission than placebo in adults with major depressive episodes, although study designs and follow-up periods varied.

The key practical limitation is durability. A single treatment may help for days rather than months, and symptoms can return. Some clinics use a short series of treatments and then reassess whether maintenance treatment is appropriate. There is no universally established schedule for racemic ketamine, so treatment frequency should follow an individualized clinical plan rather than a fixed promise. For a closer look at timing questions, see how far apart low-dose ketamine treatments may be spaced.

Intravenous ketamine and intranasal esketamine are different options

Racemic ketamine contains two mirror-image forms of ketamine and is often administered intravenously in research and clinical settings. For depression, this use is generally off label in the United States. Esketamine is one form of ketamine. The FDA approved intranasal esketamine, Spravato, for adults with treatment-resistant depression in combination with an oral antidepressant and for certain adults with depressive symptoms associated with acute suicidal ideation or behavior.

These approaches differ in formulation, administration, evidence base, monitoring programs, availability, and cost. They should not be treated as interchangeable. The FDA prescribing information for Spravato describes required monitoring for sedation, dissociation, and blood pressure increases after administration.

Rapid changes in suicidal thinking require clinical care

Ketamine has been studied for rapidly reducing suicidal thinking, and some trials have reported improvement over a short time frame. That finding does not mean ketamine alone prevents suicide or replaces a safety plan, crisis support, hospitalization when needed, or ongoing depression treatment. A clinician should evaluate immediate risk and arrange the level of care that fits the situation.

Side effects and monitoring

Common short-term effects can include dissociation, dizziness, nausea, sedation, perceptual changes, and temporary increases in blood pressure or heart rate. Dissociation is a feeling of being detached from oneself, one's surroundings, or both. Effects often occur during or soon after treatment, but intensity and duration vary.

Ketamine can create additional risk for people with certain cardiovascular conditions, uncontrolled hypertension, psychosis, or a history of problematic substance use. It can also interact with other medicines or substances. Alcohol and sedating medications may increase impairment or sedation risk, so patients should review all prescriptions, over-the-counter medicines, supplements, and substance use with the treating clinician. See our overview of ketamine and alcohol safety risks for related considerations.

Ketamine is a Schedule III controlled substance in the United States. Structured assessment, observed administration when indicated, vital-sign monitoring, transportation planning after treatment, and follow-up can help clinicians manage foreseeable risks. Do not drive, operate machinery, or make important decisions until a clinician says it is safe to do so.

Who may be a candidate

A person may be considered for ketamine-based treatment when depression has persisted despite appropriate prior care and a clinician believes potential benefits outweigh risks. A thorough evaluation should confirm the diagnosis, review previous treatments, assess bipolar-spectrum symptoms and psychosis, check cardiovascular history and blood pressure, and discuss substance-use history.

Ketamine may not be a suitable option for everyone. Active psychosis, uncontrolled medical conditions, uncontrolled hypertension, pregnancy-related considerations, or a clinical history that raises concern about misuse can change the decision. The treating team should also review whether psychotherapy, medication changes, transcranial magnetic stimulation, electroconvulsive therapy, or other approaches are relevant.

Questions to ask before choosing a ketamine provider

A useful consultation should make the treatment plan and its limits clear. Ask how the provider evaluates treatment resistance, who performs psychiatric assessment, what monitoring occurs during and after treatment, how medication interactions are handled, and what follow-up happens if symptoms return or worsen.

What to expect from a responsible treatment plan

A responsible plan has more than a dosing visit. It includes informed consent, screening for contraindications and medication interactions, monitoring during treatment, a plan for post-treatment impairment, symptom measurement, and coordination with ongoing mental health care. Psychotherapy may be part of a broader care plan, though the best way to combine it with ketamine is still being studied.

It is reasonable to ask how success will be measured. A clinician may use validated symptom scales, functional goals, and direct discussion of mood, sleep, anxiety, and safety. Improvement should be reviewed over time, not assumed from a single positive experience. People considering treatment can also review our article on common ketamine side effects before an appointment.

Bottom line

Low dose ketamine depression treatment has evidence for rapid symptom improvement in some people with TRD, especially over the short term. The evidence is strongest when treatment is part of qualified psychiatric care with clear screening, monitoring, and follow-up. Discuss the full range of options with a licensed clinician who knows your medical and psychiatric history.