Ketamine-assisted therapy combines a low dose of ketamine, a dissociative anesthetic, with psychotherapy to treat depression and other mood disorders. It works on two levels: the drug temporarily blocks certain receptors in the brain, triggering a cascade of chemical changes that promote the growth of new neural connections, while the altered mental state it produces can open a window for deeper therapeutic work. The approach has gained significant attention because ketamine can reduce depressive symptoms within hours, compared to the weeks traditional antidepressants typically require.
What Ketamine Does in the Brain
Ketamine’s antidepressant effects start with its ability to block a type of receptor called NMDA receptors. These receptors normally respond to glutamate, the brain’s primary excitatory chemical messenger. But ketamine doesn’t simply quiet things down. By blocking NMDA receptors on specific inhibitory brain cells in the prefrontal cortex, it actually removes a brake on neural activity. The result is a rapid surge of glutamate release that activates a different set of receptors (called AMPA receptors) on neighboring neurons.
This burst of activity sets off a chain reaction. It stimulates the release of BDNF, a protein that acts like fertilizer for brain cells, promoting their growth and survival. BDNF then activates signaling pathways that kick-start protein synthesis, essentially giving neurons the raw materials to build new connections. In animal studies, ketamine increased levels of key structural proteins in the prefrontal cortex, the brain region most involved in mood regulation and decision-making. When researchers blocked this protein synthesis pathway, ketamine’s antidepressant effects disappeared entirely.
How Ketamine Rebuilds Neural Connections
Depression is associated with the loss of dendritic spines, the tiny protrusions on brain cells where neurons form connections with each other. Ketamine appears to reverse this damage. Research published in Biological Psychiatry found that ketamine rapidly enhances the brain’s ability to grow new dendritic spines in the prefrontal cortex, with timing that matches when patients start feeling better. This process also involves dopamine signaling, specifically through a type of dopamine receptor that activates an enzyme needed to stabilize new connections.
What’s notable is the timeline. The initial boost in spine growth happens quickly, within hours. But the structural remodeling, where spine density measurably increases, emerges well after the drug has left the body. This suggests ketamine doesn’t just provide temporary relief. It sets in motion physical changes in brain architecture that outlast the drug itself. Within 3 hours of administration, new receptors begin appearing on neuron surfaces in the hippocampus (a region critical for memory and emotion), and by 24 hours, these changes extend to the prefrontal cortex as well.
The Therapy Component
The “assisted therapy” part distinguishes this approach from simply receiving ketamine as a medication. In a typical protocol, the treatment unfolds in three phases: preparation, the dosing session, and integration.
During preparation, a therapist helps you identify intentions for the session and establishes a framework for the experience ahead. Ketamine at sub-anesthetic doses produces an altered state of consciousness that can include feelings of dissociation, floating, visual distortions, and shifts in how you perceive yourself and your problems. Some people describe experiencing emotional material from a detached, less reactive vantage point, which can make difficult thoughts and memories easier to examine.
Integration sessions happen afterward, sometimes the same day and often over the following days or weeks. This is where you process what came up during the ketamine experience with your therapist, working to translate insights into lasting changes in thought patterns and behavior. Proponents argue that the combination is more powerful than either element alone: ketamine opens a biological window of heightened neuroplasticity, and therapy takes advantage of that window to help rewire habitual patterns of thinking.
What a Session Looks Like
Ketamine can be administered several ways, each with a different setting and experience. Intravenous (IV) infusion is the most studied route for depression. The standard dose is 0.5 mg/kg of body weight, though some patients respond to doses as low as 0.1 mg/kg and others need up to 0.75 mg/kg. An IV infusion typically lasts about 40 minutes, and you remain in the clinic for monitoring afterward.
Intramuscular injection is another option, using similar dosing ranges. Intranasal delivery is the route used by Spravato (esketamine), the only form with FDA approval specifically for treatment-resistant depression. Spravato sessions last 20 to 40 minutes for the administration itself, followed by a mandatory observation period.
Regardless of the route, expect to have your blood pressure checked before and after dosing (ketamine can cause temporary spikes) and to be monitored for at least two hours. You won’t be able to drive yourself home. The acute effects, including dissociation and altered perception, typically resolve within a couple of hours, though you may feel mentally foggy or tired for the rest of the day.
How Long the Effects Last
The antidepressant effects from a single infusion are real but temporary, typically lasting 1 to 10 days. This is why ketamine therapy is almost always delivered as a series of sessions rather than a one-time treatment. A common initial protocol involves six infusions over two to three weeks, followed by maintenance sessions spaced further apart based on how long your response holds.
The goal of pairing ketamine with psychotherapy is partly to extend this window. By using integration therapy during the period of heightened neuroplasticity, the hope is that new patterns of thinking become structurally embedded in the brain’s rewired circuitry, reducing the need for ongoing ketamine sessions over time. How well this works varies considerably from person to person, and many patients do need periodic booster sessions.
Who Can and Can’t Receive Ketamine Therapy
Ketamine therapy is primarily used for treatment-resistant depression, meaning depression that hasn’t responded to at least two standard antidepressants. It’s also being used for PTSD, severe anxiety, and suicidal ideation, though evidence is strongest for depression.
Several conditions disqualify someone from treatment. According to guidelines from the American Psychiatric Nurses Association, these include:
- Active substance abuse of any kind, including alcohol and cannabis
- History of psychosis
- Uncontrolled high blood pressure
- Unstable cardiovascular disease
- Current pregnancy
- History of increased pressure in the skull
- Previous negative reaction to ketamine
Clinics often require a urine drug screen before starting treatment and may repeat it during the course of therapy.
Cost and Insurance Coverage
Cost is one of the biggest barriers to access. IV ketamine infusions typically run $400 to $800 per session, and if psychotherapy is included, that’s often billed separately at a similar rate. Since IV ketamine isn’t FDA-approved for mental health conditions, most insurers classify it as experimental and won’t cover it. If your clinician is out of network, you can submit a claim and potentially get 20 to 50 percent reimbursed, but this varies widely by plan.
Spravato (esketamine) is a different story. Because it has FDA approval, most major commercial and government insurance plans cover it. If your clinic is in-network, you’ll typically pay your standard office visit copay, often $30 to $50. There are a few insurers beginning to cover IV ketamine as well: Blue Cross Blue Shield of Massachusetts covers IV ketamine for depression using criteria similar to their esketamine policy, and Kaiser Permanente in the San Francisco Bay Area offers some coverage. But these remain exceptions.
Even when ketamine itself isn’t covered, surrounding services sometimes are. Initial consultations, lab work, follow-up visits, and psychotherapy sessions can often be billed to insurance when documented as medically necessary. It’s worth asking your clinic exactly what they can and can’t bill before starting treatment.
Spravato vs. Generic Ketamine
Spravato contains esketamine, one of the two mirror-image molecules that make up regular ketamine. It’s the only ketamine-based treatment with FDA approval for depression, and it comes with strict safety requirements. The FDA mandates that Spravato can only be administered in certified healthcare settings. Patients must be enrolled in a special monitoring program, take the nasal spray under direct observation of a healthcare provider, and remain on-site for at least two hours afterward with pulse oximetry monitoring.
Generic ketamine, by contrast, is used off-label for depression. Clinics have more flexibility in how they administer it and structure the therapeutic experience around it. This flexibility is part of what allows the more therapy-intensive models to exist, where longer sessions incorporate guided psychotherapy during or immediately after the ketamine experience. The trade-off is less regulatory oversight and, as noted, less insurance coverage.