IV vs Oral vs Nasal Ketamine: Comparing Treatment Methods

IV vs oral vs nasal ketamine comparing treatment methods comes down to four factors: bioavailability, onset speed, monitoring intensity, and cost. Bioavailability is the percentage of an administered dose that actually reaches the bloodstream, and it is the biggest reason these routes feel so different in practice. Intravenous (IV) infusion delivers close to 100% of the dose and has the largest body of published clinical trial evidence for depression and anxiety. Intranasal esketamine, sold under the brand name Spravato, is the only ketamine formulation with FDA approval for treatment-resistant depression. Oral and sublingual ketamine absorb far less of each dose, but they can be taken at home under telehealth supervision, which lowers cost and cuts out travel time. This guide compares bioavailability, onset, side effects, monitoring requirements, and typical cost drivers for each route so you have concrete criteria to discuss with a prescriber.

Bioavailability Determines How Much Ketamine Reaches the Brain

Every ketamine route delivers a different fraction of the dose into the bloodstream. IV infusion delivers close to 100%. Intramuscular (IM) injection, an injection into muscle tissue rather than a vein, delivers roughly 90-93%. Intranasal ketamine lands in the 25-50% range depending on the formulation and technique. Sublingual troches held under the tongue reach roughly 20-35%, and ketamine that is swallowed reaches only about 16-24% of the bloodstream because the liver breaks down a large portion before it reaches systemic circulation, a process called first-pass metabolism. For a deeper look at how absorption works across routes, see our bioavailability guide. Ketamine itself is included on the WHO Model List of Essential Medicines, which reflects its established role in anesthesia and its growing use in mental health care.

These differences in absorption change how doses are calculated. A patient who swallows a 200 mg oral dose may absorb only 32-48 mg into the bloodstream, while the same 200 mg given intravenously delivers the full amount. This is why oral and sublingual prescriptions use higher milligram totals than IV protocols aiming for a comparable effect.

IV Ketamine Infusion

IV infusion delivers ketamine directly into the bloodstream through an IV line, dissolved in a saline solution and administered with an infusion pump that controls the delivery rate. The standard psychiatric protocol, established in early Yale research and replicated across hundreds of clinical trials, uses 0.5 mg/kg of body weight infused over 40 minutes. Because a nurse or clinician must place the IV line and monitor vital signs throughout the infusion and recovery period, IV treatment typically carries the highest per-session cost of the three routes.

Oral and Sublingual Ketamine

Oral and sublingual ketamine are compounded formulations prepared by specialty compounding pharmacies, usually as troches, rapid-dissolve tablets, or liquid solutions. Sublingual dosing involves holding the medication under the tongue for 10-15 minutes so it absorbs through the mucous membranes, while oral dosing means swallowing the medication for absorption through the digestive tract. Most at-home ketamine programs prescribe sublingual formulations because the sublingual route reaches higher bioavailability than the oral route. Because these doses are taken at home without an in-clinic visit, sublingual and oral ketamine typically cost less per dose than IV or intranasal treatment, though patients still pay for the compounded medication itself and periodic telehealth check-ins with a prescriber.

Intranasal Ketamine (Spravato)

Intranasal ketamine in a clinical setting almost always refers to esketamine, sold under the brand name Spravato and manufactured by Janssen Pharmaceuticals. Esketamine is the S-enantiomer of the ketamine molecule, and it is FDA-approved for treatment-resistant depression and for major depressive disorder with suicidal thoughts. The FDA approved Spravato in 2019 for adults with treatment-resistant depression, defined as an inadequate response to at least two antidepressants in the current episode. The medication is self-administered as a nasal spray under direct medical supervision, at a dose of 56 mg or 84 mg, and patients stay in the clinic for at least two hours of monitoring after dosing.

Spravato is distributed under a Risk Evaluation and Mitigation Strategy (REMS), an FDA-required safety program that limits a medication to certified prescribers and facilities meeting specific monitoring requirements. Because Spravato requires a REMS-certified facility and two hours of in-clinic monitoring per dose, its per-session cost tends to run higher than at-home oral or sublingual ketamine, though its FDA approval means some insurance plans and patient assistance programs may help offset the cost for eligible patients. For background on how the S-enantiomer compares to standard racemic ketamine, see our racemic vs esketamine comparison.

Head-to-Head: Effectiveness

Large trials directly comparing IV, oral, and intranasal ketamine head-to-head in the same study are limited, so cross-route comparisons rely on separate trial populations rather than one apples-to-apples study. Within that limitation, IV infusion has the strongest and most consistent trial evidence for rapid antidepressant and anti-anxiety effects, with response rates for treatment-resistant depression reported in the roughly 50%-70% range across published studies. Intranasal esketamine showed efficacy in the phase III trials that led to its FDA approval, with response rates in that range as well. According to the National Institute of Mental Health, ketamine's rapid-acting effects have made it an active area of psychiatric research beyond its original use as an anesthetic. Oral and sublingual ketamine have shown benefit in observational studies and clinical practice, but the evidence quality is lower because fewer randomized controlled trials have tested these routes directly. See our treatment-resistant depression guide for more on how response is typically measured.

How to Choose the Right Method

IV infusion tends to fit patients who want the most evidence-backed option with precise dosing, have reasonable access to an infusion clinic, and are comfortable with continuous in-person monitoring. Intranasal esketamine tends to fit patients with a documented treatment-resistant depression diagnosis, insurance coverage or patient assistance eligibility, and access to a certified REMS facility. Oral or sublingual ketamine tends to fit patients who value at-home convenience, are watching cost closely, do not have a nearby clinic, and have symptoms stable enough for at-home treatment as determined by a provider. Our candidacy guide covers the broader medical and psychiatric factors a provider will screen for before prescribing any route.

Many patients start with one method and move to another as treatment progresses. A common pattern is an initial series of IV infusions to establish response, followed by a transition to sublingual maintenance dosing, which balances the initial response data from IV with the ongoing affordability of at-home treatment.

Combining Methods

Some treatment plans use more than one route. A clinician might prescribe an initial series of IV infusions to establish a treatment response, then move the patient to sublingual lozenges for ongoing maintenance. A patient on at-home oral ketamine might also receive occasional IV booster infusions during periods of increased symptom severity. These hybrid approaches combine the strengths of each method while managing its practical limits, and any combination should be coordinated by a single prescribing provider to keep dosing and monitoring consistent.