Ketamine Dosing Explained: Therapeutic Ranges by Route

Ketamine dosing varies widely depending on the route of administration, the condition being treated, and individual patient factors. Therapeutic doses for depression are far below the levels used for surgical anesthesia, and there is no single "standard" dose that fits every patient or every protocol. This guide explains the dose ranges commonly cited in the published literature, why doses differ by route, and what titration means in practice.

Specific milligram amounts in any educational article are reference points only. Dosing decisions for an individual must come from a licensed clinician who has reviewed the patient's medical history and treatment goals.

What Sub-Anesthetic Dosing Means

Ketamine was originally approved in 1970 as a general anesthetic. Anesthetic induction doses are typically in the range of 1.0 to 4.5 mg/kg IV, depending on the procedure and adjuvant medications. At these levels, patients are fully sedated and require airway management.

Psychiatric and pain protocols use a fraction of those 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 roughly 40 minutes. Patients remain awake, can speak, and breathe independently, though most experience some dissociation and transient cardiovascular effects.

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 proportional benefit. Studies on dose-response relationships are still ongoing.

Dosing by Route of Administration

Because each route has different bioavailability and onset characteristics, clinicians use route-specific dose ranges rather than a single number. The table below summarizes commonly cited adult ranges from the published literature on depression treatment.

Approximate Dose Ranges by Route

Route | Typical Adult Range (Depression) | Bioavailability | Onset

IV infusion | 0.5 mg/kg over 40 min (range 0.3-1.0 mg/kg) | 100% | Within minutes

Intramuscular | 0.5-1.0 mg/kg | ~93% | 5-15 minutes

Intranasal (Spravato esketamine) | 56 mg or 84 mg per session | ~48% | 20-40 minutes

Sublingual (compounded) | 50-300 mg per session | ~25-30% | 15-30 minutes

Oral (compounded) | 100-500 mg per session | ~16-24% | 30-60 minutes

Bioavailability percentages are approximate and vary across studies. Lower-bioavailability routes use higher milligram totals to deliver a comparable systemic exposure, but the relationship is not strictly linear because oral and sublingual ketamine produce more of the metabolite norketamine, which has its own pharmacological activity.

How Titration Works

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.

Clinicians weighing whether to increase a dose typically consider:

1. Symptom response measured with validated scales such as the PHQ-9 or MADRS.
2. Acceptability of dissociation, nausea, and lightheadedness during prior sessions.
3. Blood pressure and heart rate response during and after dosing.
4. Persistence of benefit between sessions.
5. Concurrent medications that may blunt or amplify ketamine's effects.

Some patients reach an effective dose within the first one or two sessions; others need stepwise increases. A subset never tolerates higher doses well and may benefit more from frequency adjustments than from larger amounts.

Why Doses Differ by Indication

Depression protocols are not the only ketamine dosing context. Chronic pain, complex regional pain syndrome, and acute suicidal ideation each have their own published 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. Anesthetic doses are several times higher and produce full sedation.

These different protocols are not interchangeable. A dose appropriate for one indication is not necessarily safe or effective for another, and crossing them without clinical guidance is not appropriate.

Maintenance and Long-Term Dosing

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; others require ongoing periodic sessions.

Evidence is mixed on 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 minimize this risk.

Safety, Contraindications, and Final Thoughts

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.

Dosing decisions should always come from a licensed clinician familiar with ketamine pharmacology and the patient's medical history. Self-adjusting take-home doses, splitting doses across days without guidance, or combining ketamine with sedatives outside a treatment plan can be dangerous. Talk to a licensed clinician before starting or modifying any ketamine protocol.