Ketamine treatments use low doses of an anesthetic drug to treat severe depression, chronic pain, and other conditions that haven’t responded to standard therapies. Originally developed as a surgical anesthetic in the 1960s, ketamine has gained widespread clinical use at much smaller doses for its rapid effects on mood and pain signaling. Unlike traditional antidepressants that can take weeks to work, ketamine can produce noticeable changes within hours to days.
How Ketamine Works in the Brain
Traditional antidepressants target serotonin or norepinephrine, two chemical messengers involved in mood regulation. Ketamine takes an entirely different approach. It blocks a specific receptor called the NMDA receptor, which is part of the brain’s glutamate system. Glutamate is the brain’s primary excitatory chemical, responsible for how neurons communicate and form new connections.
At the low doses used therapeutically, ketamine triggers a surge of glutamate release in the prefrontal cortex, the region involved in decision-making, emotional regulation, and complex thought. This burst of glutamate stimulates other receptors and sets off a chain reaction that promotes the growth of new neural connections, essentially helping the brain rewire pathways that depression or chronic pain may have weakened. At high anesthetic doses, the effect reverses and glutamate levels actually decrease, which is why the therapeutic “sweet spot” matters so much.
This glutamate-driven mechanism also increases dopamine release in the prefrontal cortex, which likely contributes to the rapid mood improvements patients report. The speed of this process is what sets ketamine apart: while conventional antidepressants gradually shift brain chemistry over weeks, ketamine’s glutamate surge can begin reshaping neural circuits almost immediately.
Conditions Ketamine Treats
The two primary uses for ketamine treatment are treatment-resistant depression (TRD) and chronic pain. In psychiatry, “treatment-resistant” typically means a patient has tried at least two different antidepressant medications without adequate improvement. For these patients, ketamine offers a different biological pathway when the standard options have failed.
For chronic pain, ketamine works by interrupting a process called central sensitization, where the nervous system gets stuck in a heightened state of reactivity and amplifies pain signals even after the original injury has healed. Conditions like complex regional pain syndrome (CRPS), fibromyalgia, and neuropathic pain are among the most commonly treated. Pain protocols generally involve higher cumulative doses and more sessions than psychiatric protocols.
Ketamine is also being studied and used clinically for PTSD, obsessive-compulsive disorder, severe anxiety, and suicidal ideation, though evidence for these applications is still developing.
FDA Approval and Off-Label Use
This is where things get slightly complicated. The FDA has approved ketamine only as a general anesthetic. All psychiatric and pain management uses of generic ketamine are considered “off-label,” meaning doctors prescribe it based on clinical evidence even though it hasn’t gone through the formal approval process for those specific conditions.
However, in 2019, the FDA approved esketamine (brand name Spravato), a nasal spray that contains one of ketamine’s two mirror-image molecular forms. Spravato is specifically approved for treatment-resistant depression and is administered under medical supervision in certified healthcare settings. This distinction between FDA-approved esketamine and off-label generic ketamine has significant implications for cost and insurance coverage.
How Ketamine Is Administered
Ketamine can be delivered several ways, each with different absorption rates, onset times, and intensity of effects.
- Intravenous (IV) infusion: The most common clinical method. It delivers ketamine directly into the bloodstream with 100% absorption and reaches peak effect within about one minute. Because it can be adjusted in real time, providers can slow or stop the infusion if side effects become uncomfortable.
- Intramuscular (IM) injection: A shot into the muscle with 93% absorption and peak effect in about five minutes. Simpler to administer than IV but less adjustable once given.
- Intranasal spray: This includes both generic ketamine spray and FDA-approved esketamine (Spravato). Absorption runs 40 to 50%, with peak effect at around 15 minutes. Esketamine is roughly 1.8 times more potent than the generic version at equivalent doses.
- Oral (pill or liquid): The lowest absorption at 15 to 25%, with peak effect taking one to two hours. Because so much is lost during digestion, the dissociative effects are milder. Oral forms are sometimes prescribed for at-home use between clinic visits.
IV and IM routes produce stronger dissociative effects and are always administered in a clinical setting. Oral and sublingual forms, with their lower bioavailability, are occasionally prescribed for home use at a provider’s discretion.
What a Typical Treatment Course Looks Like
For depression, most clinics follow an induction phase of six infusions spread over two to three weeks. Each IV session typically lasts 40 minutes to an hour, with additional monitoring time afterward. Patients usually stay at the clinic for about two hours total per visit.
After the induction phase, patients who respond well transition to maintenance sessions. These are spaced further apart, often starting at once every two weeks and gradually extending to monthly or less frequent visits depending on how long the benefits last. Some people maintain improvements for weeks between sessions; others need more frequent boosters. There is no standardized long-term protocol yet, so treatment plans are individualized.
For chronic pain, infusions tend to be longer (sometimes several hours) and may involve higher cumulative doses delivered over a series of sessions. Pain treatment protocols vary more widely between providers than psychiatric ones do.
Side Effects During Treatment
The most characteristic side effect is dissociation, a feeling of detachment from your body or surroundings. This can range from mild floatiness to a more intense altered state where time feels distorted and your sense of self shifts. Research involving over 100 patients with depression found that dissociative symptoms peak around 40 minutes into an IV infusion and typically resolve shortly after the infusion ends.
Blood pressure and heart rate also rise during treatment. Studies show both systolic and diastolic blood pressure increase significantly from about 5 to 40 minutes after infusion begins, which is why clinics monitor vital signs throughout. Other common effects include nausea, dizziness, blurred vision, and feeling “strange” or dream-like. For most people, these effects fade within an hour or two of the session ending.
You won’t be able to drive after a session. Most clinics require you to arrange a ride home and recommend taking it easy for the rest of the day.
Who Should Not Receive Ketamine
Ketamine is not appropriate for everyone. Key exclusion criteria include a history of psychosis or active psychotic symptoms, uncontrolled high blood pressure, significant vascular aneurysms, and current substance abuse. People who lack the cognitive capacity to understand the risks and benefits of treatment are also excluded.
Because ketamine raises blood pressure, anyone with cardiovascular concerns needs careful evaluation before starting treatment. Providers should conduct a thorough medical and psychiatric history before recommending ketamine for any condition.
Cost and Insurance Coverage
Cost is one of the biggest barriers to ketamine treatment. A single IV infusion at a private clinic typically runs $400 to $800, which means an induction course of six infusions can cost $2,400 to $4,800 or more before maintenance sessions even begin.
Because generic ketamine is used off-label for depression and pain, most insurance plans, including Medicare, do not cover it for these purposes. Some providers have found workarounds by billing ketamine infusions under generic drug infusion codes, which certain insurers will partially reimburse, but this varies widely.
Spravato (esketamine nasal spray) has a clearer path to coverage. Because it carries FDA approval for treatment-resistant depression, Medicare Part D and many private insurance plans cover it, though patients typically need to meet specific criteria, such as documented failure of prior antidepressant trials. Even with coverage, copays can be substantial. Checking with your insurer before starting treatment is essential to understanding your actual out-of-pocket costs.