Ketamine Treatment Methods Guide: Every Route of Administration Explained

Overview of Ketamine Delivery Methods

One of ketamine's advantages as a therapeutic agent is its versatility. Unlike many psychiatric medications that are limited to oral dosing, ketamine can be administered through multiple routes, each with distinct pharmacological properties, clinical advantages, and practical considerations.

The choice of administration method affects bioavailability (the percentage of the dose that reaches the bloodstream), onset of action, duration of effects, cost, setting requirements, and the overall patient experience. There is no single "best" method — the optimal choice depends on the clinical context, the condition being treated, patient preferences, provider expertise, and logistical factors.

This guide provides a detailed comparison of every currently used method of ketamine delivery.

Understanding Bioavailability

Before examining individual methods, it is essential to understand bioavailability — the fraction of an administered dose that reaches systemic circulation in active form. Bioavailability is expressed as a percentage, with intravenous administration defined as 100% (since the entire dose enters the bloodstream directly).

Different routes of ketamine administration have dramatically different bioavailabilities:

These differences mean that achieving equivalent blood levels requires different doses depending on the route. For example, a 50 mg sublingual dose delivers approximately 12.5-15 mg to the bloodstream, while a 50 mg IV dose delivers the full 50 mg.

Intravenous (IV) Infusion

How It Works

IV infusion delivers ketamine dissolved in saline directly into the bloodstream through a peripheral intravenous catheter, typically placed in the arm or hand. An infusion pump controls the rate of delivery, allowing for precise dosing over a defined time period.

Standard Psychiatric Protocol

The most widely studied and commonly used protocol for depression involves:

• Dose: 0.5 mg/kg of body weight
• Infusion duration: 40 minutes
• Frequency: Two to three times per week
• Initial series: Six infusions over two to three weeks
• Maintenance: Individualized, typically one infusion every two to six weeks

Some clinics use modified protocols with slightly higher or lower doses, longer infusion times, or different scheduling based on clinical experience and emerging research.

Pain Protocol

Pain-focused IV protocols typically differ significantly from psychiatric protocols:

• Higher doses: Often 0.5-1.0 mg/kg per hour, sometimes higher
• Longer durations: 2-4 hours per session, or multi-day continuous infusions
• Different scheduling: 3-5 consecutive days for conditions like CRPS
• Inpatient options: Prolonged continuous infusions in hospital settings

Advantages

• Gold standard bioavailability — 100% of the dose reaches the bloodstream
• Precise dose control — The infusion rate can be adjusted in real time
• Most studied method — The vast majority of clinical evidence for psychiatric ketamine comes from IV studies
• Rapid onset — Effects begin within 1-2 minutes of starting the infusion
• Medical oversight — Administered in clinical settings with continuous monitoring
• Titratable — The infusion can be slowed or stopped if side effects become uncomfortable

Disadvantages

• Cost — Typically $400-$800 per session; most insurance does not cover off-label IV ketamine
• Setting requirements — Requires a clinical facility with IV capabilities and monitoring equipment
• Time commitment — Each session requires 1-2 hours including preparation, infusion, and recovery
• IV access — Some patients find needle placement uncomfortable or have difficult venous access
• Frequency of visits — The initial series requires multiple visits per week

Who It Is Best For

IV infusion is often recommended for patients seeking the most evidence-based approach, those with treatment-resistant depression who need rapid symptom relief, patients with complex chronic pain conditions, and individuals who prefer the security of full medical monitoring during treatment.

Intranasal Administration

FDA-Approved Esketamine (Spravato)

Spravato is a nasal spray containing esketamine (the S-enantiomer of ketamine) approved by the FDA in March 2019 for treatment-resistant depression and later expanded to include major depressive disorder with suicidal ideation. It is the only form of ketamine with specific FDA approval for a psychiatric indication.

Dosing Protocol

• Induction phase (weeks 1-4): 56 mg or 84 mg twice weekly
• Maintenance phase (weeks 5-8): 56 mg or 84 mg once weekly
• Extended maintenance (week 9+): 56 mg or 84 mg once weekly or every two weeks
• Each dose is self-administered under supervision using a nasal spray device

Administration Procedure

1. Patient arrives at a certified healthcare facility (REMS-certified)
2. Baseline vital signs are taken
3. Patient self-administers the nasal spray under medical observation
4. Two-hour post-dose monitoring period begins
5. Vital signs are checked periodically during monitoring
6. Patient must not drive for the remainder of the day

Compounded Intranasal Ketamine

Some practitioners prescribe compounded racemic ketamine nasal spray, prepared by compounding pharmacies. This is an off-label use and is not subject to the REMS requirements of Spravato. Compounded formulations are typically less expensive but lack the standardized dosing and manufacturing consistency of the FDA-approved product.

Advantages

• FDA-approved (Spravato) — Regulatory validation for treatment-resistant depression
• Insurance coverage — More likely to be covered by insurance than off-label IV ketamine
• Non-invasive — No needles or IV access required
• Self-administered — Patient controls the spray application under supervision
• Standardized dosing — Spravato devices deliver precise, consistent doses

Disadvantages

• REMS requirements — Spravato can only be administered in certified facilities with mandatory monitoring
• Lower bioavailability — Approximately 45-50%, requiring higher nominal doses
• Variable absorption — Nasal congestion, technique, and mucosal condition can affect absorption
• Esketamine only — Spravato uses only the S-enantiomer, not the racemic mixture used in most research
• Cost — Spravato's list price is significant, though insurance may offset this
• Two-hour monitoring — Each session requires a substantial time commitment

Who It Is Best For

Intranasal ketamine, particularly Spravato, is often appropriate for patients whose insurance covers it, those who prefer an FDA-approved treatment, patients who want to avoid IV access, and individuals who value the regulatory safeguards of the REMS program.

Oral and Sublingual Administration

How They Work

Oral ketamine formulations are typically prepared by compounding pharmacies as tablets, troches (lozenges), or liquid solutions. The two primary oral routes differ in how the medication is absorbed:

• Sublingual — The tablet or troche is placed under the tongue and allowed to dissolve, with absorption occurring through the oral mucosa directly into the bloodstream. After a specified hold time (typically 10-15 minutes), remaining liquid is either spit out or swallowed.
• Oral (swallowed) — The medication is swallowed and absorbed through the gastrointestinal tract. It undergoes significant first-pass metabolism in the liver before reaching systemic circulation, resulting in lower bioavailability.

Typical Dosing

Because of lower bioavailability, oral and sublingual doses are higher in absolute milligrams than IV doses to achieve comparable blood levels:

• Sublingual troches: 100-400 mg, with the medication held under the tongue for 10-15 minutes
• Oral tablets or liquid: 0.5-2.0 mg/kg, adjusted based on individual response
• Frequency: Varies widely — from daily to two to three times per week for acute treatment, with tapering to maintenance schedules

At-Home Protocols

Oral and sublingual ketamine are the most common forms prescribed for at-home use. Typical at-home protocols include:

1. Initial assessment and possibly in-office treatment sessions
2. Prescription of compounded formulation with specific dosing instructions
3. Telehealth or in-person follow-up appointments to assess response and adjust dosing
4. Guidelines for safe administration (having a sitter present, no driving afterward, quiet environment)
5. Regular check-ins with the prescribing clinician

Some providers require patients to use monitoring apps, complete symptom surveys, or participate in video-observed dosing sessions.

Advantages

• Home convenience — Can be used at home without traveling to a clinic
• Lower cost — Compounded formulations are typically $50-$200 per month
• Non-invasive — No needles, IV lines, or nasal sprays
• Flexibility — Dosing schedules can be adjusted more easily
• Familiar format — Taking a tablet or lozenge is less intimidating for many patients
• Broader access — Available through telehealth providers, expanding geographic reach

Disadvantages

• Lower bioavailability — Sublingual: ~25-30%; oral: ~17-20%, requiring higher doses
• Variable absorption — Eating, drinking, saliva production, and technique affect how much medication is absorbed
• Higher first-pass metabolism — Swallowed ketamine produces more norketamine (a metabolite with different properties) relative to ketamine itself
• Less medical oversight — At-home use involves less direct monitoring than in-office treatments
• Compliance variability — Proper sublingual technique (adequate hold time, avoiding swallowing) is important for consistent results
• Taste — Many patients find the taste of ketamine unpleasant, even in flavored formulations

Who It Is Best For

Oral and sublingual formulations are well-suited for maintenance therapy after an initial response to IV or other in-office treatment, patients in rural areas or locations without nearby ketamine clinics, individuals who are cost-sensitive, patients with stable conditions who do not require intensive monitoring, and those who prefer the convenience and privacy of at-home treatment.

Intramuscular (IM) Injection

How It Works

IM injection delivers ketamine directly into muscle tissue, typically the deltoid (upper arm) or gluteal (buttock) muscle. The medication is absorbed from the muscle into the bloodstream. Absorption is rapid due to the rich blood supply of muscle tissue.

Dosing

• Typical psychiatric dose: 0.5-1.0 mg/kg
• Onset: 3-5 minutes after injection
• Peak effects: 15-30 minutes
• Duration of acute effects: 45-90 minutes

Administration Setting

IM ketamine is administered in clinical settings, including:

• Ketamine therapy clinics
• Psychiatric offices
• Ketamine-assisted psychotherapy (KAP) sessions
• Emergency departments (for acute suicidal ideation)

Advantages

• High bioavailability — Approximately 93%, nearly matching IV delivery
• No IV access needed — A single injection eliminates the need for IV placement and infusion equipment
• Rapid onset — Effects begin within minutes
• Simpler logistics — Does not require infusion pumps, IV tubing, or saline bags
• Cost-effective — Less equipment and potentially less staff time than IV infusion
• Predictable pharmacokinetics — Absorption is more consistent than oral or sublingual routes

Disadvantages

• Less titratable — Once injected, the dose cannot be adjusted in real time (unlike IV infusion where the rate can be changed)
• Injection discomfort — Some patients experience pain, bruising, or soreness at the injection site
• Less studied — Fewer controlled clinical trials compared to IV infusion for psychiatric indications
• Bolus effect — The entire dose is absorbed relatively quickly, which can produce more intense peak effects compared to the gradual delivery of IV infusion
• Clinical setting required — Like IV infusion, IM injection typically requires an in-office visit

Who It Is Best For

IM injection is appropriate for patients who want high bioavailability without IV access, those in ketamine-assisted psychotherapy sessions (where the more defined onset and peak may complement the therapeutic process), patients who find IV placement uncomfortable or have difficult veins, and clinical settings where infusion equipment is not available.

Rectal Administration

A Less Common Route

Rectal administration of ketamine, while less commonly discussed, is sometimes used in specific clinical situations, particularly in pediatric settings for procedural sedation. Its bioavailability is approximately 25-30%, similar to sublingual administration.

This route is rarely used for psychiatric treatment in adults but may occasionally be considered for patients who cannot tolerate oral medication or other routes of administration.

Continuous Infusion Protocols

Extended IV Infusions for Pain

For certain chronic pain conditions, particularly complex regional pain syndrome (CRPS), some specialized centers offer extended continuous ketamine infusions lasting from several hours to multiple days. These are conducted in inpatient or intensive outpatient settings with comprehensive monitoring.

Protocol Variations

• Multi-hour outpatient: 2-6 hour infusions at moderate doses
• Multi-day inpatient: 3-5 days of continuous infusion at carefully escalated doses, sometimes reaching significantly higher cumulative doses than standard psychiatric protocols
• Coma-inducing protocols: Extremely high-dose protocols inducing a medically managed coma, used only in select international centers for severe refractory pain conditions

These extended protocols require specialized medical expertise, intensive monitoring, and careful patient selection.

Ketamine-Assisted Psychotherapy (KAP)

Integration of Medicine and Therapy

KAP is not a separate route of administration but rather a treatment framework that combines ketamine administration with structured psychotherapy. It can use any of the delivery methods described above, though sublingual, IM, and IV routes are most common in KAP settings.

The KAP Model

A typical KAP protocol involves three phases:

1. Preparation sessions — Psychotherapy sessions before ketamine administration to establish therapeutic goals, build rapport, discuss expectations, and introduce coping strategies for the ketamine experience
2. Medicine sessions — Ketamine is administered while a therapist provides support. The altered state of consciousness is used as a therapeutic tool. Sessions may include guided meditation, music, or gentle therapeutic dialogue
3. Integration sessions — Follow-up psychotherapy sessions to process and integrate the insights, emotions, and experiences from the medicine session into everyday life and ongoing therapeutic work

Theoretical Rationale

The rationale for KAP is that ketamine creates a window of enhanced neuroplasticity and psychological openness. During this window:

• Defensive psychological barriers may be temporarily lowered
• Patients may access emotional material that is otherwise difficult to reach
• The dissociative state can provide a sense of distance from trauma and emotional pain, allowing for new perspectives
• Enhanced neuroplasticity may make therapeutic insights more likely to produce lasting neural and behavioral changes

Current Evidence

Research on KAP is growing but remains in earlier stages than research on ketamine alone. Several clinical trials have produced encouraging results, particularly for alcohol use disorder and PTSD. A key question is whether the addition of structured psychotherapy produces more durable results than ketamine alone — early evidence suggests it may, but larger controlled trials are needed.

Comparing Methods: A Practical Decision Framework

Factor 1: Clinical Urgency

For patients in acute psychiatric crisis (active suicidal ideation, severe treatment-resistant depression), IV infusion or IM injection may be preferred due to their high bioavailability and rapid onset. These methods offer the most predictable and rapid response.

Factor 2: Evidence Base

IV infusion has the strongest clinical evidence for psychiatric indications, followed by intranasal esketamine (Spravato). Oral, sublingual, and IM routes have growing evidence but fewer large-scale randomized controlled trials.

Factor 3: Cost and Insurance

Spravato is most likely to be covered by insurance — see our insurance coverage guide. IV infusion is typically out-of-pocket. Oral and sublingual formulations are generally the least expensive option. IM injection falls in between.

Factor 4: Convenience and Access

Oral and sublingual formulations offer the most convenience, particularly with telehealth prescribers. IV and IM require clinic visits. Spravato requires visits to REMS-certified facilities.

Factor 5: Medical Monitoring Needs

Patients with cardiovascular concerns, complex medical histories, or those new to ketamine therapy may benefit from the intensive monitoring available with IV infusion. Stable patients on maintenance therapy may be appropriate for at-home oral or sublingual protocols.

Factor 6: Treatment Phase

Many patients benefit from a phased approach:

1. Acute phase: IV infusion or in-office treatment for initial symptom relief
2. Transition phase: Gradual shift to a more sustainable maintenance method
3. Maintenance phase: Oral, sublingual, or periodic booster infusions as needed

Emerging Delivery Methods

Extended-Release Formulations

Pharmaceutical companies are developing extended-release oral formulations of ketamine that could provide more consistent blood levels with once-daily or less frequent dosing, potentially improving both efficacy and convenience.

Transdermal Delivery

Transdermal patches delivering ketamine through the skin are under investigation. This route could offer steady-state drug levels over extended periods without the variability of oral dosing or the inconvenience of repeated injections or infusions.

Inhaled Formulations

Beyond nasal spray, inhaled ketamine (via nebulizer or inhaler) is being explored as a delivery method that could offer faster onset than oral routes with better standardization than compounded nasal sprays.

Summary Comparison Table

References

• Andrade, C. "Ketamine for Depression, 4: In What Dose, at What Rate, by What Route, for How Long, and at What Frequency?" Journal of Clinical Psychiatry, 2017. — Comprehensive review of ketamine dosing across administration routes.
• Daly, E.J., et al. "Efficacy and safety of intranasal esketamine adjunctive to oral antidepressant therapy in treatment-resistant depression." JAMA Psychiatry, 2018. — Key clinical trial supporting Spravato's FDA approval.
• Peltoniemi, M.A., et al. "Ketamine: A review of clinical pharmacokinetics and pharmacodynamics in anesthesia and pain therapy." Clinical Pharmacokinetics, 2016. — Detailed pharmacokinetic comparison across routes of administration.
• National Institute of Mental Health. "Mental Health Medications." — NIMH resource on psychiatric medications including ketamine-based therapies.
• Mayo Clinic. "Treatment-resistant depression." — Mayo Clinic overview of treatment options for treatment-resistant depression.