Ketamine for Depression: What You Need to Know

Published by Battaglia Integrative Psychiatry | battagliaintegrativepsychiatry.com

Depression is one of the most common and disabling conditions we treat. For many patients, standard antidepressants — SSRIs, SNRIs, and others — provide meaningful relief. But for roughly one in three people with major depressive disorder, those medications simply don't work well enough. This group, often diagnosed with treatment-resistant depression (TRD), has historically had very limited options. Ketamine has changed that conversation dramatically.

Here's what you need to know about ketamine as a treatment for depression: how it works, what the evidence shows, what to expect in terms of side effects, how it's given, what the FDA has approved — and importantly, how it differs from other substances in the psychedelic space that you may have heard about.

A Brief History of Ketamine

Ketamine has been FDA-approved as a surgical anesthetic since 1970 and has a long track record of safe use in hospitals and emergency settings worldwide. Researchers began noticing something unexpected decades ago: patients who received ketamine for anesthesia sometimes reported dramatic, rapid improvements in mood — even patients who had struggled with depression for years. This observation launched a new era of psychiatric research, leading to the development of esketamine (Spravato®) and a growing body of evidence for ketamine's role in mental health care.

How Does Ketamine Work?

Most traditional antidepressants target monoamine neurotransmitters — primarily serotonin, norepinephrine, and dopamine. Ketamine works through an entirely different mechanism. It is an NMDA receptor antagonist, meaning it blocks a specific type of glutamate receptor in the brain. Glutamate is the brain's most prevalent excitatory neurotransmitter, and blocking NMDA receptors appears to trigger a cascade of effects that rapidly promote synaptic plasticity and neurogenesis — essentially helping the brain form new connections.

This is a fundamentally different way of treating depression, which helps explain why ketamine can work in patients who haven't responded to conventional approaches.

What Is Ketamine FDA-Approved For?

This is an important distinction for patients to understand.

Racemic ketamine (the form that contains both mirror-image molecular structures of the compound) has been FDA-approved as an anesthetic since 1970. When psychiatrists administer IV ketamine infusions for depression, this is considered off-label use — meaning it is not FDA-approved for that specific indication, but it is a legally and medically accepted practice supported by substantial clinical evidence.

Esketamine (Spravato®), the S-enantiomer of ketamine delivered as a nasal spray, has received specific FDA approvals for psychiatric conditions:

• 2019: Approved as an adjunctive treatment for treatment-resistant depression (TRD) in adults — meaning patients who have tried at least two adequate antidepressant courses without sufficient benefit.
• 2020: Approved for major depressive disorder (MDD) with acute suicidal ideation or behavior in adults.
• January 2025: The FDA approved Spravato as the first standalone treatment for TRD — a significant milestone, as it can now be used without requiring a concurrent oral antidepressant.

Esketamine is dispensed under a Risk Evaluation and Mitigation Strategy (REMS), which means it must be administered and monitored in a certified healthcare setting. Patients self-administer the nasal spray but must remain under clinical observation for at least two hours following each dose.

Efficacy: What Does the Evidence Show?

The evidence for ketamine's antidepressant effects is compelling, and what sets it apart from every other treatment in psychiatry is the speed of response.

Where traditional antidepressants typically take four to six weeks (or longer) to produce meaningful benefit, ketamine can produce noticeable improvements in mood within hours to days of administration. This rapid onset is especially significant for patients experiencing acute suicidal ideation, where time matters enormously.

Key efficacy findings include:

• In multiple randomized controlled trials, a significant proportion of patients with TRD achieved response (meaningful symptom reduction) or remission after a series of ketamine or esketamine treatments.
• Depression affects approximately 5.7% of adults worldwide, and about one-third of those develop TRD. Ketamine represents one of the few treatment options with robust evidence in this difficult-to-treat population.
• Both IV ketamine and intranasal esketamine have demonstrated comparable acute effectiveness in head-to-head studies, with neither clearly superior.
• Ketamine's anti-suicidal effects are well-documented and occur rapidly, making it a valuable tool in acute psychiatric settings.

It's important to note that ketamine is not a permanent cure. The antidepressant effects can fade over time, and many patients require maintenance infusions or ongoing treatment to sustain benefit. Combining ketamine with psychotherapy and other integrative approaches can help extend and deepen its effects.

Modes of Administration

Ketamine can be delivered in several ways, each with different clinical profiles:

Intravenous (IV) Infusion The most widely studied route for psychiatric use. A carefully calibrated dose (typically 0.5 mg/kg) is infused over 40–60 minutes. This allows precise dosing and rapid clinical adjustment. A standard course usually involves six to eight infusions over two to four weeks, followed by maintenance sessions as needed. IV administration requires a clinical setting with monitoring equipment.

Intramuscular (IM) Injection Ketamine can also be injected directly into muscle tissue. Studies comparing IM to IV ketamine have found comparable antidepressant effects, with IM being somewhat simpler to administer. It is a viable option for some patients and clinical settings.

Intranasal (Esketamine / Spravato®) The FDA-approved route for psychiatric indications. Patients self-administer the nasal spray in a certified clinic and are then monitored for at least two hours. This format is more accessible than IV infusion and allows for standardized, regulated dosing.

Oral Ketamine Oral formulations exist and are sometimes used, but they are not FDA-approved for psychiatric conditions and carry more variable absorption. The FDA has specifically cautioned healthcare providers about potential risks associated with compounded oral ketamine products used for psychiatric disorders.

Side Effects and Tolerability

Ketamine has a strong overall safety profile when used in supervised medical settings. The vast majority of side effects are temporary, dose-dependent, and resolve within one to two hours of administration.

Common side effects include:

• Dissociative symptoms (feeling detached from one's body or surroundings, a dreamlike or "floaty" quality)
• Dizziness and blurred vision
• Nausea
• Transient increases in blood pressure and heart rate
• Headache
• Anxiety during the session

At a clinical research level, studies involving low-dose ketamine infusions in over 160 patients found no serious drug-related adverse events, with side effects such as dissociation, visual shifts, and mild disorientation peaking within an hour and fully resolving within two.

Important monitoring considerations: The cardiovascular effects of ketamine — particularly transient blood pressure elevation — require monitoring during and after administration. This is one reason why ketamine treatment must always occur in a medical setting with appropriate oversight. Patients with certain cardiovascular conditions may require additional evaluation before starting treatment.

Longer-term considerations: Frequent, high-dose, or unsupervised ketamine use is associated with risks that do not apply to clinical psychiatric dosing — including bladder problems (ketamine cystopathy) and potential for psychological dependence. At therapeutic doses in monitored settings, the risk of abuse or addiction appears low, and studies have not demonstrated cognitive decline or increased craving over three-month follow-up periods. That said, ketamine is a Schedule III controlled substance, and its use warrants careful clinical oversight.

How Ketamine Differs from "Classic" Psychedelics: Psilocybin, DMT, and MDMA

As public interest in psychedelic-assisted therapy grows, patients often ask how ketamine relates to substances like psilocybin (magic mushrooms), DMT (found in ayahuasca), and MDMA (ecstasy). While all of these substances can alter consciousness and are being studied for mental health applications, they are pharmacologically quite different from one another — and from ketamine.

Mechanism of Action

This is the most fundamental distinction:

Ketamine is a dissociative anesthetic that works primarily by blocking NMDA glutamate receptors. Its altered states are a byproduct of its glutamatergic activity, not the primary mechanism of its antidepressant effect. Ketamine does not act significantly on serotonin receptors.

Psilocybin and DMT are classic serotonergic psychedelics. They work primarily as agonists at the 5-HT2A serotonin receptor. This mechanism produces profound changes in perception, thought, and emotion — the classic "psychedelic trip." The same receptor activation triggers a glutamate surge in specific brain regions, which may explain their neuroplasticity-promoting properties.

MDMA is technically an empathogen or entactogen — not a classic hallucinogenic psychedelic. It works by massively increasing the release of serotonin, dopamine, and norepinephrine, producing emotional warmth, feelings of connectedness, and reduced fear. MDMA is not primarily a hallucinogen, and its mechanism is pharmacologically distinct from both ketamine and classical psychedelics.

The Quality of Experience

The subjective experience differs meaningfully across these substances:

Ketamine tends to produce a more internal, dissociative experience — a gentle detachment from the body and ordinary thought patterns, sometimes described as "stepping outside one's mental loops." Visuals are usually subtler than with classic psychedelics.

Psilocybin and DMT produce experiences that can be intensely visual, emotionally profound, and spiritually significant. They often involve dramatic alterations in perception, a dissolution of the ordinary sense of self, and experiences that patients frequently describe as among the most meaningful of their lives. The intensity can also be challenging, and set and setting matter enormously.

MDMA produces emotional openness, heightened empathy, and reduced defensiveness — qualities that have made it particularly interesting in the context of trauma therapy. The experience is often described as feeling safe, connected, and emotionally accessible.

Legal Status and Clinical Availability

This is perhaps the most practically important distinction for patients today:

Ketamine is Schedule III (lower abuse potential than Schedule I or II drugs) and is legally available for use in clinical settings. IV ketamine and esketamine (Spravato®) are both available at psychiatric practices like ours right now.

Psilocybin and DMT remain Schedule I controlled substances at the federal level in the United States, meaning they are classified as having no currently accepted medical use, though this classification is increasingly contested. Psilocybin is in late-stage clinical trials for depression and has shown promising results, but it is not yet legally available outside of approved research settings in most states.

MDMA is also Schedule I. It had received FDA Breakthrough Therapy Designation for PTSD, and clinical trials showed impressive results — in one major study, 67% of participants no longer met criteria for PTSD after MDMA-assisted therapy. However, as of now MDMA has not received FDA approval and remains in the research phase.

In short: ketamine offers many of the therapeutic qualities people are seeking from psychedelic-assisted therapy — altered consciousness, rapid mood improvement, neuroplasticity — with the structure, oversight, and legal accessibility of an established medical treatment. It is the only compound in this broader conversation that is currently available as part of standard psychiatric care.

Is Ketamine Right for You?

Ketamine treatment is not appropriate for everyone, and it is not a first-line treatment. Candidates are typically those who:

• Have been diagnosed with treatment-resistant depression (failed two or more adequate antidepressant trials)
• Are experiencing major depression with acute suicidal ideation (in certain clinical contexts)
• Are medically stable with no contraindications (such as uncontrolled hypertension, active psychosis, or certain substance use disorders)

A thorough psychiatric and medical evaluation is essential before beginning ketamine treatment. At Battaglia Integrative Psychiatry, we take an individualized, evidence-based approach — integrating ketamine with psychotherapy, lifestyle medicine, and other treatments to support lasting recovery.

A Note on the Evolving Landscape

The field of psychedelic psychiatry is moving quickly. Psilocybin, MDMA, and other compounds may eventually join ketamine in the clinical toolkit, and we follow the research closely. For now, ketamine represents a remarkable bridge: a proven, accessible, FDA-recognized tool that has already helped thousands of patients find relief from depression that once seemed untreatable.

If you have questions about whether ketamine treatment might be right for you or a loved one, we invite you to schedule a consultation. We're here to help you navigate these options with clarity and care.

Battaglia Integrative Psychiatry | battagliaintegrativepsychiatry.com

This blog post is for educational purposes only and does not constitute medical advice. Please consult a qualified psychiatric provider to discuss your individual treatment options.