The standard dose of ketamine for depression is 0.5 mg/kg of body weight, delivered as an intravenous infusion over 40 minutes. For a 150-pound person, that works out to roughly 34 mg per session. Some patients respond to doses as low as 0.1 mg/kg, while others need up to 0.75 mg/kg. The exact amount depends on the method of delivery, your body weight, and how you respond to initial treatments.
IV Ketamine: The Most Studied Dose
Intravenous ketamine at 0.5 mg/kg is the dose used in the vast majority of clinical trials for treatment-resistant depression. It’s infused slowly over 40 minutes in a medical setting, not given all at once. This “subanesthetic” dose is far below what would be used for surgical anesthesia, which is part of why side effects remain manageable for most people.
Clinical studies support a safe and effective range of 0.5 to 1.0 mg/kg based on actual body weight. The dose is calculated using your real weight, not an idealized number from a chart. Research published in Pharmacological Reports found that using ideal body weight instead of actual weight can lead to underdosing, especially in people with a higher BMI. Because ketamine is fat-soluble and crosses into the brain easily, actual body weight produces more consistent results. That said, clinicians do watch cardiovascular effects more carefully in overweight patients, since blood pressure spikes can be more pronounced.
Esketamine Nasal Spray (Spravato)
The FDA-approved nasal spray version uses esketamine, a mirror-image molecule of ketamine. It comes in fixed doses rather than weight-based ones. The starting dose is 56 mg on day one, with subsequent doses of either 56 mg or 84 mg depending on how you respond and tolerate it. During the first four weeks (the induction phase), you receive it twice per week. After that, the frequency tapers to once a week or once every two weeks.
Spravato must be taken in a certified healthcare setting, where you’re monitored for at least two hours afterward. It cannot be picked up at a pharmacy and used at home.
Sublingual and Oral Ketamine
Some clinics and telehealth providers prescribe compounded ketamine lozenges (also called troches) for at-home use. These are not FDA-approved for depression, but they are legal when prescribed off-label by a licensed provider. Typical sublingual doses range from 100 to 300 mg per session. The higher milligram number compared to IV reflects the fact that much less of the drug reaches your bloodstream when absorbed through the mouth. Bioavailability for sublingual ketamine is roughly 25 to 30 percent, so a 200 mg lozenge delivers a fraction of what a 34 mg IV infusion does.
How Quickly It Works
Ketamine’s appeal for depression is speed. Improvement in depressive symptoms can begin within 40 minutes of an IV infusion. The strongest effects typically peak around 24 hours after the dose. A single infusion can reduce symptoms for three to seven days on average, though some people lose the benefit sooner and others retain it for 10 to 12 days.
This is dramatically faster than traditional antidepressants, which often take four to six weeks to show full effects. Ketamine also appears to reduce suicidal thinking within hours, which is one reason it has drawn so much clinical interest for patients in crisis.
Typical Treatment Schedule
A standard IV induction course involves two or three infusions per week for two to four weeks. That means most people receive six to eight infusions during the initial phase. After induction, the goal shifts to maintaining the response with less frequent “booster” sessions. Some protocols space boosters at every two weeks, which appears to be enough for many patients. Others may need monthly sessions or occasional infusions when symptoms return.
There is no universally agreed-upon maintenance schedule yet. Clinicians adjust the frequency based on how long your symptom relief lasts between sessions.
What Happens During a Session
IV ketamine is administered in a clinic or medical office, not a hospital. You sit in a recliner or lie on a bed while the infusion runs for 40 minutes. Staff monitor your blood pressure, heart rate, and oxygen levels before, during, and after treatment. Blood pressure commonly rises during the infusion. Guidelines recommend pausing treatment if systolic pressure exceeds 160 mmHg or diastolic exceeds 100 mmHg, and stopping entirely if those numbers reach 180/110. For this reason, patients with uncontrolled high blood pressure (baseline readings above 140/90) are generally not treated until their pressure is better managed.
Most people experience some dissociation, a feeling of being detached from their body or surroundings. This is dose-dependent. At 0.1 mg/kg, dissociative effects are minimal. At 0.3 mg/kg, they become noticeable. At the standard 0.5 mg/kg, they are common but temporary, typically fading within an hour or two after the infusion ends. Nausea, dizziness, and a temporary increase in anxiety can also occur. You’ll need someone to drive you home.
Dose Adjustments for Specific Groups
Older adults generally receive the same 0.5 mg/kg IV dose used in younger patients. A pilot study in older adults with treatment-resistant depression used this standard dose and found it tolerable, though clinicians tend to be more cautious with monitoring. Patients taking benzodiazepines are sometimes asked to reduce their dose before treatment, since benzodiazepines may blunt ketamine’s antidepressant effects. Those on antipsychotics may also have their doses reviewed, with some providers recommending a reduction.
If you don’t respond to the initial 0.5 mg/kg dose after several infusions, your provider may gradually increase it. The upper range explored in clinical settings goes up to 1.0 mg/kg, though most dose adjustments stay closer to 0.75 mg/kg. Each increase is made cautiously, with closer monitoring of blood pressure and dissociative side effects.
Why Self-Dosing Is Risky
Ketamine is a Schedule III controlled substance with real potential for abuse and dependence. At recreational doses, which are significantly higher than clinical ones, it can cause hallucinations, delusions, and long-term cognitive problems. Even at clinical doses, repeated use without medical oversight raises concerns about bladder damage, liver stress, and psychological dependence. The careful weight-based dosing, vital sign monitoring, and structured treatment schedules used in clinical settings exist specifically to keep the risk-benefit balance favorable.