IV Ketamine vs. Nasal Spray vs. Oral Forms

IV Ketamine vs. Nasal Spray vs. Oral Forms

Patients researching ketamine treatment often discover that it can be administered in several different ways — intravenous infusion, intramuscular injection, nasal spray, and oral or sublingual forms — and quickly find that clinics and providers don’t always agree on which is best. Each route of administration has a different evidence base, a different regulatory status, and different practical implications. This article compares them directly.

## Intravenous (IV) Infusion

IV ketamine involves administering the racemic (standard, non-isolated) form of ketamine directly into a vein over a controlled period, commonly around 40 minutes for depression protocols, delivered through a small IV line placed by clinical staff.

**Evidence base.** IV administration has the longest track record in the psychiatric research literature — most of the foundational studies on ketamine for depression, going back to the early 2000s, used IV administration, giving it the deepest and most extensive body of supporting research among the off-label options.

**Regulatory status.** IV ketamine for depression is used off-label; there is no FDA-approved indication specifically for IV ketamine in depression, though ketamine itself has long-standing FDA approval as an anesthetic.

**Practical considerations.** IV administration allows for precise, controlled dosing and the ability to adjust or halt the infusion during the session if needed, since the medication enters the bloodstream directly and gradually. It requires placement of an IV line, which some patients find more invasive or uncomfortable than other routes, and it generally requires a clinical setting equipped for IV administration.

**Bioavailability.** Because the medication is delivered directly into the bloodstream, IV administration achieves essentially complete bioavailability (the medication isn’t lost to absorption inefficiencies), which allows for more predictable and precise dosing compared to routes that rely on absorption through tissue.

## Intramuscular (IM) Injection

Intramuscular ketamine involves a single injection, typically into the upper arm or thigh, delivering the racemic form of the medication.

**Evidence base.** IM administration has a smaller, though still meaningful, body of supporting research compared to IV administration, with some studies suggesting broadly comparable effectiveness, though direct head-to-head comparisons are limited.

**Regulatory status.** As with IV administration, IM ketamine for depression is used off-label.

**Practical considerations.** IM injection is generally quicker and simpler to administer than IV infusion, not requiring an IV line, which some patients find preferable. However, once injected, the dose cannot be adjusted or stopped mid-administration the way an IV infusion can, meaning the full dose is committed to once given.

**Bioavailability.** IM administration generally has somewhat lower and more variable bioavailability compared to IV administration, since the medication must be absorbed from the muscle tissue into the bloodstream, though this absorption is still considerably more efficient and predictable than oral administration.

## Esketamine Nasal Spray (Spravato)

Esketamine nasal spray is the only ketamine-related product route with full FDA approval specifically for a psychiatric indication (treatment-resistant depression and depressive symptoms with suicidal ideation), as discussed in detail in an earlier article in this series.

**Evidence base.** Esketamine’s approval rests on a series of large, well-controlled clinical trials specifically designed to meet FDA standards, giving it a particularly rigorous and standardized evidence base for its specific approved indications, though this evidence is narrower in scope (limited to its approved indications) compared to the broader range of off-label research conducted with IV racemic ketamine.

**Regulatory status.** FDA-approved, with a formal Risk Evaluation and Mitigation Strategy (REMS) program governing its administration, including mandatory in-clinic observation for at least two hours after each dose.

**Practical considerations.** Nasal administration avoids the need for an IV line or injection, and the patient self-administers the medication (under direct observation), which some patients find preferable. However, absorption through the nasal mucosa can be somewhat variable between individuals, and the device requires specific technique (including a waiting period between sprays for higher doses) to ensure adequate dosing.

**Bioavailability.** Intranasal bioavailability is generally lower and more variable than IV administration, given the need for absorption across the nasal mucosa, though esketamine’s specific formulation and dosing were designed and studied with this administration route in mind.

## Oral and Sublingual Forms

Some providers offer ketamine in oral (swallowed) or sublingual (dissolved under the tongue) forms, generally compounded specifically for this purpose since there is no FDA-approved oral ketamine product for depression.

**Evidence base.** This is the least studied of the major administration routes for depression, with a smaller number of published studies compared to IV, IM, or intranasal administration, and considerably less standardization in dosing and formulation across different compounding pharmacies and providers.

**Regulatory status.** Oral or sublingual ketamine for depression is used off-label and, because it typically relies on compounded formulations rather than a single standardized product, involves additional variability in quality and dosing consistency depending on the compounding pharmacy used.

**Practical considerations.** Oral and sublingual forms are the most convenient in terms of not requiring an in-clinic procedure for administration, and some providers use them for at-home maintenance dosing following an initial in-clinic treatment series, or as one component of an extended treatment protocol. This convenience needs to be weighed against the lower level of direct medical supervision during dosing compared to clinic-administered routes, and questions some researchers have raised about consistency of absorption and effect with these forms.

**Bioavailability.** Oral ketamine undergoes significant first-pass metabolism in the liver, meaning a substantial portion of an oral dose is broken down before reaching systemic circulation, resulting in considerably lower and more variable bioavailability compared to IV, IM, or intranasal routes. This is one of the more significant pharmacological differences among the various administration methods and is an important factor in why oral dosing protocols differ substantially from those used for other routes.

## Comparing Bioavailability and Practical Implications

| Route | Relative Bioavailability | FDA Approval Status | Typical Setting |
|—|—|—|—|
| IV infusion | Highest (essentially complete) | Off-label for depression | Clinic, IV line required |
| Intramuscular | High, somewhat variable | Off-label for depression | Clinic, single injection |
| Intranasal (esketamine) | Moderate, variable | FDA-approved (specific indications) | Clinic, self-administered under observation |
| Oral/sublingual | Lowest, most variable | Off-label, often compounded | Clinic or, in some protocols, at home |

## Which Route Is “Best”?

As with many comparative questions in this series, there isn’t a single universally correct answer — the appropriate route depends on the specific clinical situation, the evidence supporting a given indication, practical considerations like insurance coverage and access to a qualified provider, and individual patient factors and preferences.

For patients specifically seeking an FDA-approved treatment pathway with standardized dosing and a formal safety monitoring program, esketamine nasal spray is the only option currently meeting that description. For patients and providers working within the off-label ketamine space, IV administration carries the deepest and most extensive supporting research base among the off-label routes, though IM and, to a lesser extent, oral/sublingual forms are used by various providers based on their own clinical experience and specific treatment goals.

## Questions Worth Asking a Provider

Given this variability, patients evaluating different administration routes may want to ask a prospective provider:

– Why is this specific route being recommended for my situation?
– What evidence supports this administration method for my specific condition?
– If oral or sublingual ketamine is being proposed, which compounding pharmacy is used, and what quality controls are in place?
– How does the monitoring protocol differ (if at all) based on the administration route being used?

## The Bottom Line

IV infusion, intramuscular injection, intranasal esketamine, and oral/sublingual forms each represent meaningfully different approaches to delivering ketamine, with different levels of supporting evidence, different regulatory status, and different practical and pharmacological trade-offs. Understanding these differences allows patients to have a more informed conversation with their provider about why a particular route is being recommended for their specific situation, rather than assuming all forms of “ketamine treatment” are functionally interchangeable.

*This article is for educational purposes only and does not constitute medical advice. The appropriate administration route for any individual should be determined in consultation with a licensed healthcare provider.*