Ketamine Dosing Explained: Therapeutic Ranges by Route

Ketamine dosing depends on the route of administration, the condition being treated, and the individual patient, which is why no single milligram number applies to every protocol. The most replicated antidepressant dose for IV ketamine is 0.5 mg/kg infused over about 40 minutes, a fraction of the 1.0 to 4.5 mg/kg used for surgical anesthesia. Doses for intranasal, sublingual, and oral ketamine are set higher in milligram terms because each of those routes delivers less of the drug into the bloodstream. This guide breaks down the ketamine dosing ranges reported in the published literature by route, explains how titration works, and outlines the safety factors a clinician weighs before adjusting a dose.

Specific milligram amounts in this article are educational reference points, not a personal dosing recommendation. Any decision about starting, adjusting, or stopping ketamine dosing should come from a licensed clinician who has reviewed the patient's full medical history.

Ketamine was approved by the FDA in 1970 as a general anesthetic, and anesthetic induction doses are typically 1.0 to 4.5 mg/kg IV depending on the procedure and any adjuvant medications. At those doses, patients are fully sedated and require airway management by a trained anesthesia provider.

Psychiatric and pain protocols use a fraction of those anesthetic amounts, generally one-quarter to one-tenth. The most replicated antidepressant dose is 0.5 mg/kg of racemic ketamine given as an IV infusion over about 40 minutes. In the trial that established this dose, researchers reported rapid improvement in treatment-resistant depression symptoms within hours of a single infusion (Zarate et al., 2006Archives of General Psychiatry, via PubMed). At 0.5 mg/kg, patients remain awake, can speak, and breathe independently, though most experience some dissociation and transient increases in blood pressure and heart rate.

The therapeutic window for antidepressant effect appears to sit in a relatively narrow band. Doses well below 0.3 mg/kg IV may produce weaker or unreliable responses in some studies, while doses above roughly 1.0 mg/kg IV tend to increase side effects without a proportional increase in benefit. Researchers are still studying the exact shape of this dose-response curve.

Bioavailability percentages above are approximate and vary across studies. Lower-bioavailability routes use higher milligram totals to reach a comparable systemic exposure, but the relationship is not strictly linear. Oral and sublingual ketamine produce more of the metabolite norketamine, which has its own pharmacological activity and may contribute differently to the treatment effect than IV or intramuscular dosing.

For a side-by-side look at how these routes perform, see our comparison of IV, oral, and nasal ketamine. Readers weighing the difference between standard racemic ketamine and the FDA-approved esketamine nasal spray can review racemic ketamine vs. esketamine. Compounded sublingual and oral formulations come from specialty compounding pharmacies rather than a single FDA-approved manufacturer; see how compounding pharmacies prepare ketamine for what that means for quality control. Intramuscular dosing, covered in our guide to intramuscular ketamine, sits between IV and oral routes in both bioavailability and convenience.

Titration is the practice of starting at a conservative dose and adjusting upward across sessions based on tolerability and symptom response. Most ketamine protocols include some form of titration, though it is more visible in oral and sublingual programs where dose changes happen across separate take-home sessions rather than within a single visit.

Some patients reach an effective dose within the first one or two sessions; others need stepwise increases across a series. A subset never tolerates higher doses well and may benefit more from adjusting frequency than from larger amounts. For more on what dissociation feels like and how clinicians assess it during titration, see understanding dissociation.

Depression protocols are not the only ketamine dosing context. Chronic pain, complex regional pain syndrome, and acute suicidal ideation each have their own published dose ranges, and procedural sedation uses higher doses still.

Pain protocols sometimes use longer infusions, hours rather than minutes, at total doses comparable to or larger than antidepressant doses. Acute suicidal ideation interventions have generally used the standard 0.5 mg/kg IV dose with rapid follow-up care. Anesthetic doses remain several times higher and produce full sedation rather than the alert, sub-anesthetic state used in psychiatric protocols.

These different protocols are not interchangeable. A dose appropriate for one indication is not necessarily safe or effective for another, and crossing between them without clinical guidance is not appropriate. Readers researching how ketamine protocols are structured for treatment-resistant depression specifically can see optimizing ketamine protocols for treatment-resistant depression.

After an initial series, commonly six IV infusions over two to three weeks, or a roughly equivalent course of intranasal or sublingual sessions, patients who respond may transition to maintenance dosing. Maintenance intervals are highly individualized, ranging from weekly to quarterly. Some patients eventually taper off entirely, while others require ongoing periodic sessions.

Evidence is mixed on the optimal maintenance frequency, and recommendations continue to evolve as longer-term data accumulate. Tolerance has been reported in some clinical contexts, particularly with frequent dosing, though structured intermittent protocols appear to reduce this risk.

Standard ketamine dosing is generally avoided or substantially modified for people with uncontrolled hypertension, recent cardiovascular events, active psychosis, untreated bipolar disorder, pregnancy, severe hepatic impairment, or a history of ketamine cystitis. Concurrent benzodiazepines may blunt antidepressant effects, and certain mood stabilizers can interact with ketamine's mechanism of action. Readers who want a fuller rundown of side effects and interactions can see common ketamine side effects and whether ketamine therapy is safe. For background on how ketamine produces its effects at the receptor level, see how ketamine works.