Ketamine Dosing: Routes of Administration, Bioavailability, and What the Research Shows
Ketamine is a valuable treatment option for conditions including depression, chronic pain, PTSD, and more — and it can be delivered through several different routes, each with distinct clinical and experiential profiles. Dosing is highly individualized. There is no universal protocol, and the route of administration matters as much as the dose itself.
Bioavailability Depends on Route
Bioavailability refers to the percentage of a drug that reaches the bloodstream and becomes available to act on the body. The same milligram dose will produce very different effects depending on how it enters the body, which is why dosing can't be discussed without also discussing route.
Routes of Ketamine Administration
Intravenous (IV) Infusion
IV infusion delivers ketamine directly into the bloodstream, technically achieving 100% bioavailability. It is the reference standard in clinical research and allows precise, real-time dose titration throughout the session.
The standard therapeutic dose for mood disorders is 0.5 mg/kg infused over 40 minutes. A 2024 systematic review and meta-analysis from Mayo Clinic (Journal of Affective Disorders) found significant antidepressant benefit at low (0.2 mg/kg), standard (0.5 mg/kg), and higher doses (up to 1 mg/kg) — with no evidence that higher doses produce meaningfully greater benefit.
Many ketamine-assisted therapy protocols begin patients at 0.5–0.8 mg/kg and escalate by small increments across a standard series of six sessions, adjusting based on patient weight, experience, and clinical response.
Intramuscular (IM) Injection
IM ketamine is injected into muscle tissue (typically the deltoid or thigh) and carries approximately 93% bioavailability. Absorption is slightly slower than IV, so doses are adjusted upward to account for the difference. It does not require IV access, which some patients find preferable for comfort and overall experience.
A peer-reviewed case series of 40 patients with major depressive disorder receiving six IM ketamine sessions found a mean 55% reduction in PHQ-9 scores, with an effect size (Cohen's d = 1.71) comparable to published IV outcomes. The starting dose in that protocol was 1 mg/kg (maximum 60 mg), divided into two equal injections 15 minutes apart, with subsequent sessions titrated based on patient response. A separate randomized study comparing IV and IM delivery head-to-head found depression scores dropped 57–60% across both groups within two hours, supporting IM as a clinically viable route.
The onset with IM is slightly slower than IV, and the experiential quality can differ, though this varies considerably between individuals. Some patients find IM sessions feel less clinical, which can support a more relaxed therapeutic environment.
Intranasal (IN) Esketamine / Ketamine
Intranasal esketamine (Spravato) is the FDA-approved S-enantiomer of racemic ketamine, indicated for treatment-resistant depression and MDD with suicidal ideation. Bioavailability is approximately 45–50% and can be affected by anatomy, technique, and nasal mucosa health.
The Mayo Clinic meta-analysis found meaningful antidepressant effects at 56 mg and 84 mg dosed twice weekly, with 84 mg showing the strongest results. The 28 mg dose did not outperform placebo. Multiple systematic reviews indicate that IV ketamine generally outperforms intranasal esketamine in direct comparisons, though head-to-head trials remain limited — a large multi-site PCORI-funded RCT comparing the two is currently recruiting.
Oral Administration (Lozenges / Troches)
Oral ketamine has the lowest bioavailability of available routes — estimated at 23–38% — with significant variability between individuals based on metabolism. Effects are slower to onset and less predictable in intensity. Oral formats are occasionally used for supplemental at-home dosing between office-based sessions, not typically as a primary treatment modality.
What the Research Says about Dosing for Therapeutic Purposes
Regardless of route, therapeutic ketamine is administered at sub-anesthetic doses — well below those used for surgical sedation. At these levels, ketamine primarily acts on NMDA receptors, modulating glutamate signaling and initiating neuroplastic changes that underlie its rapid antidepressant effects.
A six-session series over two to three weeks is the most common initial protocol across both IV and IM routes. Research supports repeated sessions over single administration for durability: a randomized controlled trial in Translational Psychiatry found that while single and repeated infusions produced comparable effects at 24 hours post-last session, those who responded to the full series had a longer but non-statistically-significant time to relapse.
A 2024 narrative review concluded that repeated ketamine treatments show rapid, robust, and sustained antidepressant effects — while also noting that dissociative side effects, hemodynamic changes, and long-term safety remain important clinical considerations.
How Ketamine Dosing Decisions Are Made
Dosing is determined collaboratively between provider and patient, before and throughout the treatment series. Relevant factors include:
Body weight; IV and IM dosing is weight-based (mg/kg)
Medical history and current medications
Prior psychedelic or dissociative experiences
Cardiovascular health; ketamine can temporarily elevate blood pressure and heart rate
Patient-reported experience after each session, used to guide titration
Dose adjustments are made session by session. Responsible providers maintain real-time monitoring during administration and follow up in the days after each session.
The Medicine and the Container Both Matter
The pharmacology of ketamine dosing is well-documented, but the numbers are not the whole story. Set (mindset), setting (environment and provider relationship), and integration (how the experience is processed afterward) are consistently identified in the literature as significant contributors to long-term outcomes.
Whatever the route used, the quality of preparation, support, and continuity of care surrounding each session matters as much as the milligrams. At NeuroPain Health, every protocol is built around that principle. To learn more or schedule a consultation, contact our office.