Ketamine is a dissociative anesthetic with rapid-acting antidepressant and pain-relief properties. Medically, it is used for surgery as an anaesthetic and to treat treatment-resistant depression and chronic pain, all under strict clinical supervision. In this article, I outline ways ketamine can be administered.
Ketamine can be delivered by several routes, most commonly intravenous (IV) infusion, intramuscular (IM) injection, intranasal spray, and sublingual/oral formulations, with additional but less-used options such as rectal, transdermal, and others in specific clinical contexts.
Each route differs in onset, bioavailability, monitoring needs, and regulatory status, so selection is driven by indication, setting, cost, and patient-specific factors.
Key Factors
The method of administration has a significant impact on the ketamine experience, as well as its risks and applications. Key factors include [1] [2] [3] [4]:
- Bioavailability: The amount of the drug that enters the bloodstream and reaches its target site.
- Onset: How quickly the effects begin.
- Peak Effect: The time it takes to reach the maximum intensity.
- Duration: How long the primary effects last.
- Controllability: The ability to stop or slow the effects if needed.
Main Administration Routes
Intravenous (IV) infusion
IV delivers ketamine directly into the bloodstream with nearly 100% bioavailability and rapid penetration of the Central Nervous System. It allows precise titration of dose and rate, and can be slowed or stopped quickly if adverse effects emerge, which is why it remains the most studied and commonly used route in many medical settings.
Intramuscular (IM) injection
IM is given as a shot into the muscle (e.g., deltoid), providing high bioavailability (in the 90% range) and relatively rapid onset. It is simpler and less resource-intensive than IV, but once administered cannot be adjusted in real time, so any dosing changes occur only between sessions.
Intranasal (IN) spray
IN uses a spray or atomizer to deliver ketamine or esketamine (Spravato) to nasal mucosa, where it is absorbed with lower bioavailability (roughly 20–30%) and somewhat slower, but still rapid, onset. IN avoids needles, allows some dose titration within a session, and is used both in clinic-based protocols and, for esketamine, in tightly regulated programs.
Sublingual/buccal (SL) and oral
SL is administered as lozenges or tablets under the tongue or in the cheek (sublingual/buccal) or swallowed as capsules/tablets (oral). Mucosal routes partly bypass first-pass metabolism and are slower and typically less intense than other routes, whereas swallowed oral dosing has lower and more variable bioavailability and a more gradual onset.
Less common or specialized routes
Rectal, transdermal, intraosseous, spinal, and nebulized (spray) routes have been described for specific indications (e.g., analgesia, anesthesia, emergency access), but data are comparatively limited and dosing is less standardized. Their use tends to be restricted to research settings or particular procedural/anesthesia contexts where conventional routes are impractical.
Considerations for Route Selection
Efficacy and evidence base
IV infusion has the strongest evidence for depression and acute analgesia, with standardized dosing protocols and safety data.
Other routes (IM, IN, SL/oral) are increasingly used, depending on local regulations, for mood and pain.
Safety, monitoring, and regulation
All routes require medical screening and monitoring for cardiovascular effects, dissociation, and potential misuse. Professional bodies and some regulators advise particular caution with non-IV off-label routes and emphasize staying within prevailing medical practice or being able to justify deviations.
Summary Table Comparing Routes of Administration
| Method | Onset of Action | Duration | Type of Use |
| IV Infusion(Gold Standard) | 1 min. | 1-2 hours (post-infusion) | Clinical |
| IM Injection | 1-5 min | 1-2 hours | Clinical/Emergency |
| Sublingual/Oral | 15-45 min | 60-90 min (peak) | At-Home / Maintenance |
| Intranasal | 5-20 min | 45-90 min | Clinical (Spravato) / At-Home |
| Oral (Swallowed) | 30+ min | Long but weak | Not Recommended |
Important Safety and Legal Note
Ketamine is a potent dissociative anesthetic and psychedelic substance. All administration methods carry risks, especially outside of a controlled clinical setting, including:
- Psychological distress: Anxiety, panic, or confusion during the dissociative experience.
- Cardiovascular effects: Increased blood pressure and heart rate.
- Impaired motor function: You cannot drive or operate machinery for at least 24 hours.
- Potential for abuse and cystitis: Chronic, heavy use can lead to severe bladder and kidney problems.
Ketamine should only be used under the guidance of a qualified medical professional. Self-administration without a prescription and medical oversight, such as with the party drug known as Special K, is illegal and dangerous.
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Sources
[1] Rosenbaum SB, Gupta V, Patel P, et al. Ketamine. [Updated 2024 Jan 30]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-.
[2] National Pain Centers. Routes of Administration
[3] College of Physicians and Surgeons of British Colombia. 2025. Ketamine Administration via Intramuscular, Oral, Sublingual, and Intranasal Routes as Treatment for Mental Health Conditions and Chronic Pain in the Community Setting.
[4] ASKP.org. Routes of Administration (ROA).