Ketamine Therapy for Depression: What It Is, How It Works, and Who It's For

If you've been dealing with depression that hasn't responded to traditional antidepressants, you've probably felt a particular kind of frustration. The trial-and-error of SSRIs. The weeks of waiting to see if a new medication works. The side effects that sometimes feel worse than the depression itself. The creeping suspicion that maybe nothing is going to work.

Ketamine therapy has emerged as one of the most significant advances in depression treatment in decades — and unlike many things that get hyped in medicine, the evidence behind it is genuinely strong. Here's what you need to know.

What Ketamine Actually Is

Ketamine has been used in medicine since the 1960s, primarily as an anesthetic. It's on the World Health Organization's list of essential medicines. It has a decades-long safety profile in surgical and emergency settings.

What makes ketamine remarkable for psychiatry is that it works through an entirely different mechanism than traditional antidepressants. While SSRIs and SNRIs target serotonin and norepinephrine systems, ketamine acts primarily on the glutamate system through NMDA receptor antagonism.

In plain English: ketamine affects different brain chemistry than the medications that haven't been working for you. That's why it can help when other treatments have failed.

How It Works in the Brain

The neuroscience of ketamine's antidepressant effect is fascinating and still being fully understood. Here's the simplified version:

NMDA receptor blockade. Ketamine blocks a type of glutamate receptor called the NMDA receptor. This triggers a cascade of downstream effects that increase the release of brain-derived neurotrophic factor (BDNF) — essentially a growth factor for neurons.

Synaptogenesis. The BDNF release promotes the formation of new synaptic connections, particularly in the prefrontal cortex — the brain region most affected by depression. Imaging studies have shown that depression is associated with synaptic loss in this area, and ketamine appears to help restore those connections.

Rapid onset. Unlike SSRIs, which take 4-6 weeks to reach full effect, ketamine can produce noticeable improvement in mood within hours to days. This rapid onset is one of its most significant advantages, particularly for patients with severe symptoms or suicidal ideation.

Default mode network effects. There's evidence that ketamine disrupts overactivity in the brain's default mode network — the system associated with rumination, self-referential thinking, and the repetitive negative thought patterns that characterize depression.

What Treatment Looks Like

Ketamine for depression is typically administered in one of several ways:

IV infusion. The most studied route. Administered in a clinical setting over 40-60 minutes. This is the gold standard in terms of evidence but requires visiting a clinic for each session.

Intranasal (esketamine/Spravato). An FDA-approved nasal spray containing esketamine (the S-enantiomer of ketamine). Administered in a healthcare setting under observation. Covered by some insurance plans.

Sublingual/oral. Ketamine lozenges or tablets that dissolve under the tongue. This is the form most commonly used for at-home treatment under physician supervision. Lower bioavailability than IV but more accessible and convenient.

A typical treatment course involves an initial series of sessions (often 6 sessions over 2-3 weeks for IV, or a similar ramp-up for other routes), followed by maintenance sessions as needed. The frequency of maintenance varies — some patients do well with monthly sessions, others need more or less frequent treatment.

During a ketamine session, patients typically experience dissociative effects — a feeling of detachment from their body or surroundings. Some describe it as dreamlike or floating. These effects are temporary and resolve within 1-2 hours. Most patients find the experience neutral to positive, especially when they know what to expect.

Who It's For

Ketamine therapy is most established for:

Treatment-resistant depression. This is generally defined as depression that hasn't responded adequately to at least two different antidepressants at adequate doses and duration. If you've tried multiple medications without sufficient relief, ketamine is a reasonable next step.

Depression with suicidal ideation. The rapid onset of ketamine's antidepressant effect makes it particularly valuable for patients experiencing active suicidal thoughts, where waiting 4-6 weeks for an SSRI to work isn't acceptable.

Major depressive episodes. Even in patients who haven't formally failed multiple medications, ketamine can be considered when depression is severe and significantly impacting function.

Ketamine is also being studied for anxiety disorders, PTSD, OCD, and chronic pain — with varying levels of evidence.

Who Should Avoid It

Ketamine is not appropriate for everyone:

• Active psychosis or schizophrenia. Ketamine can worsen psychotic symptoms.
• Uncontrolled hypertension. Ketamine can temporarily elevate blood pressure and heart rate.
• Active substance use disorder. Particularly stimulant or dissociative substance use. The dissociative properties of ketamine carry a theoretical risk in patients with certain substance use histories, though the evidence for addiction to therapeutic ketamine is limited.
• Pregnancy. Safety data in pregnancy is insufficient.
• Certain cardiac conditions. Patients with unstable angina, recent MI, or decompensated heart failure need careful evaluation.

A thorough medical history and screening are essential before starting treatment. This is not a therapy that should be initiated without proper physician oversight.

What the Evidence Shows

The evidence for ketamine in depression is robust and growing:

• A landmark 2000 study demonstrated rapid antidepressant effects from a single IV ketamine infusion.
• Multiple randomized controlled trials have confirmed efficacy for treatment-resistant depression.
• A 2019 meta-analysis of 36 trials found that ketamine produced significantly greater improvement in depression scores compared to placebo, with effects emerging within 24 hours.
• The FDA approved esketamine (Spravato) in 2019 for treatment-resistant depression, marking the first new mechanism of action for depression approved in decades.
• Real-world data continues to support efficacy, with response rates of 60-70% in treatment-resistant populations.

These are not marginal effects. For a population that has failed other treatments, a 60-70% response rate is remarkable.

What It Costs

This is the honest part: ketamine therapy can be expensive. IV infusions typically range from $400-800 per session. Esketamine (Spravato) is covered by some insurance plans but can have high copays. Oral/sublingual ketamine through telehealth providers is generally the most affordable option, though it still represents an out-of-pocket cost for most patients.

The cost barrier is real and it's something the healthcare system needs to address. A treatment that works for treatment-resistant depression shouldn't be accessible only to those who can afford it.

How Coral Health Approaches Ketamine

At Coral Health, I offer ketamine therapy for appropriate candidates after thorough evaluation. My approach:

• Comprehensive psychiatric history and screening
• Discussion of all treatment options, not just ketamine
• If ketamine is appropriate, prescribing at-home sublingual ketamine with clear protocols for use
• Regular follow-up to assess response, adjust dosing, and monitor for side effects
• Integration with other treatments as needed — ketamine works well alongside therapy, lifestyle changes, and sometimes other medications

If you've been struggling with depression that hasn't responded to traditional treatments, ketamine therapy may be worth discussing with your physician. It's not a miracle cure — nothing in medicine is. But for many patients, it's the first thing that's actually worked.