IV, Nasal, Oral or IM: Does the Route of Ketamine Matter?

The Route Is Part of the Treatment

Ketamine is sometimes discussed as though it were a single treatment.

It isn't quite that simple.

A patient receiving racemic ketamine through an intravenous infusion is having a substantially different pharmacological—and potentially psychological—experience from someone taking a compounded ketamine lozenge at home.

Intramuscular injection introduces another pharmacokinetic profile.

Intranasal racemic ketamine introduces another.

And Spravato introduces an important additional distinction: it contains esketamine, one of ketamine's two mirror-image molecules, rather than the racemic mixture used in conventional IV ketamine.

All of these treatments are connected.

They are not equivalent.

That leads to a surprisingly complicated question:

How much does the route matter?

IV Ketamine: The Gold-Standard Route

Within the psychiatric ketamine field, intravenous administration is widely regarded as the gold-standard route for off-label racemic ketamine treatment.

There are several reasons.

IV ketamine has the most established psychiatric evidence base among routes of racemic ketamine administration.

It also offers essentially complete systemic bioavailability.

And unlike a swallowed, absorbed or injected dose, an infusion allows clinicians to control the administration of the drug over time.

Those distinctions matter.

The treatment team knows what has been administered.

Delivery is direct.

The patient can be continuously monitored.

And the infusion itself can be medically managed in real time.

But the phrase gold standard needs one qualification.

It does not mean that high-quality randomized trials have conclusively demonstrated that IV racemic ketamine produces superior outcomes to every alternative formulation, route and treatment model for every patient.

It means IV remains the reference route for racemic ketamine in psychiatric practice, supported by the deepest clinical research history and unusually controlled pharmacokinetics.

First, Ketamine Is Not Spravato

This distinction is frequently blurred.

Racemic ketamine contains two molecular forms—or enantiomers—of ketamine.

FDA-approved ketamine products are approved as anesthetics. Ketamine itself is not FDA-approved for a psychiatric indication.

Its use for depression and other psychiatric conditions is therefore off-label.

Esketamine is one of ketamine's two enantiomers.

Intranasal esketamine is marketed as Spravato and has specific FDA-approved psychiatric indications.

Spravato is also subject to a Risk Evaluation and Mitigation Strategy, or REMS, requiring administration in certified healthcare settings with monitoring afterward.

So comparing:

IV ketamine vs nasal ketamine

can already be misleading.

The comparison may actually be:

IV racemic ketamine vs intranasal esketamine.

That changes both the molecule and the route simultaneously.

Why Route Changes Pharmacology

A drug cannot produce an effect until it reaches the body in a biologically available form.

Route determines how that happens.

With IV administration, the drug enters systemic circulation directly.

Other routes introduce absorption barriers and greater variability.

Oral ketamine undergoes substantial first-pass metabolism through the gastrointestinal tract and liver before reaching systemic circulation.

Intranasal ketamine must be absorbed across nasal tissue.

Sublingual and buccal formulations rely partly on absorption through oral mucosa, while some portion may also be swallowed.

Intramuscular ketamine must be absorbed from the injection site.

These differences affect:

bioavailability

onset

peak concentration

metabolism

metabolite exposure

and variability between patients.

A route therefore does more than change how ketamine enters the body.

It changes the pharmacological event.

IV Ketamine: Precision and Control

One of IV ketamine's major advantages is control.

An oral dose, once swallowed, cannot be taken back.

An intramuscular injection cannot be gradually withdrawn after it has been administered.

An IV infusion is different.

Administration occurs over time while the patient is observed.

That creates a degree of control that is difficult to reproduce through other routes.

It also produces predictable systemic delivery because there is no absorption barrier between administration and circulation.

That does not automatically prove superior therapeutic efficacy.

But it helps explain why IV became the reference model for psychiatric ketamine research.

IM Ketamine

Intramuscular ketamine also has high systemic availability and relatively rapid onset.

It has practical advantages.

There is no need to maintain intravenous access, and administration itself is simple.

But once an IM dose has been administered, clinicians have less moment-to-moment control over drug delivery.

The psychiatric evidence base is also considerably smaller than the literature surrounding IV racemic ketamine.

That does not mean IM ketamine is ineffective.

It means:

clinical use and strength of evidence are different questions.

Intranasal Esketamine: A Different Treatment Model

Spravato occupies a unique position.

Unlike IV racemic ketamine for depression, intranasal esketamine has an FDA-approved psychiatric pathway.

That brings standardized manufacturing, labeled indications and a formal safety-monitoring framework.

Spravato must be administered under supervision in a certified healthcare setting, and patients are monitored for at least two hours afterward because of risks including sedation, dissociation and respiratory depression.

This makes Spravato particularly important for understanding an often-overlooked distinction:

regulatory approval and pharmacological superiority are not the same thing.

IV ketamine has the longer racemic-ketamine psychiatric research history.

Spravato has the FDA-approved psychiatric indication.

Both facts can be true simultaneously.

Intranasal Racemic Ketamine Is Not Spravato

Compounded intranasal racemic ketamine should not be treated as another name for Spravato.

They are different products.

The FDA has separately warned about compounded ketamine nasal sprays, which are not FDA-approved products and do not automatically carry the same manufacturing, dosing or REMS framework as Spravato.

The published evidence for intranasal racemic ketamine is also considerably less developed than the evidence supporting intranasal esketamine.

That distinction matters whenever someone says:

“nasal ketamine.”

The next question should be:

Which one?

Oral and Sublingual Ketamine

Oral and sublingual ketamine have become increasingly visible, particularly through telehealth and at-home treatment models.

The attraction is obvious.

They can be easier to administer.

They don't require IV access.

They may require fewer clinical resources.

And they can potentially reduce the cost and inconvenience of attending a treatment facility.

But convenience introduces tradeoffs.

Oral ketamine undergoes extensive first-pass metabolism.

Sublingual or buccal administration may bypass some of that process, but absorption can still vary and some of the dose may be swallowed.

This can create greater variability in exposure than direct IV administration.

The evidence supporting oral and sublingual psychiatric ketamine is also less mature than the IV evidence base.

The Rise of At-Home Ketamine

Route has also changed where ketamine treatment occurs.

That deserves attention.

The growth of oral and sublingual ketamine has enabled treatment models in which patients take compounded ketamine outside a medical facility.

FDA has warned about compounded ketamine products used for psychiatric disorders, particularly when administration occurs without onsite healthcare-provider monitoring.

Potential concerns include:

sedation,

dissociation,

changes in vital signs,

respiratory depression,

misuse,

and abuse.

This raises a broader question.

When we compare routes, are we really comparing only pharmacology?

Or are we also comparing completely different treatment environments?

Route Changes the Setting

Imagine two experiences.

In one, a patient receives ketamine through a controlled IV infusion while being continuously observed in a dedicated treatment environment.

In another, a patient takes a compounded oral product at home.

The molecule may be related.

But almost everything surrounding it has changed.

Monitoring.

Preparation.

Environment.

Sensory input.

Human support.

Predictability.

The patient's perception of safety.

And potentially the intensity and timing of the altered state.

Route therefore becomes entangled with set and setting.

That makes route comparisons much harder than simply comparing milligrams.

What We Observe at Ketamine Lounge

At Ketamine Lounge, our experience has consistently led us to regard medically supervised IV administration as the gold-standard model for the way we deliver ketamine treatment.

That view is partly pharmacological.

IV administration provides direct systemic delivery and precise control over the infusion.

But our observations suggest there may be another dimension.

We see ketamine treatment as potentially involving two therapeutic components.

The first happens during the treatment itself.

The altered state can involve significant changes in:

perception,

emotion,

self-awareness,

time,

memory,

and meaning.

Patients sometimes describe these experiences as among the most psychologically significant aspects of treatment.

The second component appears after the infusion.

Ketamine's pharmacological effects extend beyond the period in which the patient consciously feels the drug.

Research has linked ketamine's antidepressant actions to changes in glutamatergic signaling, synaptic function and neuroplasticity-related processes that may continue after the acute altered state has resolved.

From our experience and patient feedback, deeper IV experiences appear in many patients to be associated with a different therapeutic response than we observe or hear described with lower-intensity delivery approaches.

That is an observation.

It is not controlled evidence.

And it raises a question we think deserves investigation.

Does the Experience Matter?

For years, one interpretation of ketamine's antidepressant effect was essentially pharmacological:

administer the molecule,

trigger biological changes,

and improvement follows.

But the subjective experience is increasingly difficult to ignore.

Dissociation, altered self-perception, emotional experiences and occasionally profound mystical or spiritual experiences can occur during ketamine treatment.

Whether those experiences are merely side effects, markers of sufficient drug exposure, independent contributors to therapeutic change—or some combination of all three—remains unresolved.

This matters enormously when comparing routes.

Different routes can produce different:

onset profiles,

peak exposures,

durations,

and subjective trajectories.

If the acute experience contributes therapeutically, then route may matter for reasons that cannot be captured by measuring depression scores alone.

The Second Window: What Happens Afterward

Then there is the biological side.

Ketamine's effects on the brain do not simply end when the altered state ends.

Research has implicated pathways involving glutamate, AMPA signaling, BDNF-related processes and synaptic plasticity in ketamine's rapid antidepressant effects.

This has contributed to the idea of a temporary period in which neural systems may become more capable of change.

But there is an important distinction:

neuroplasticity means capacity for change—not guaranteed therapeutic change.

A more plastic system could theoretically become more receptive to learning, psychotherapy, behavior change or new emotional experiences.

That is one reason the hours and days following treatment may ultimately prove as interesting as the infusion itself.

Does More Ketamine Mean More Neuroplasticity?

This is where the science becomes less certain.

Our working hypothesis at Ketamine Lounge is that greater ketamine exposure within an appropriately selected and medically supervised therapeutic range may produce a stronger neuroplasticity-related biological response.

It is a plausible question.

It is not something we can currently claim to have proven.

Dose-response research does not demonstrate a simple linear relationship in which:

more ketamine = more neuroplasticity = better clinical outcome.

A meta-analysis of randomized dose-comparison trials found evidence of increasing antidepressant response through commonly studied IV ranges, but did not demonstrate additional clinical benefit at the highest doses examined. The authors also rated the overall evidence as limited.

Clinical outcome and neuroplasticity are also not interchangeable measurements.

A depression score cannot directly tell us how much synaptic remodeling occurred.

Likewise, laboratory evidence of plasticity does not prove that a higher dose will produce a better long-term psychiatric outcome.

So the hypothesis remains open:

Could a sufficiently robust ketamine exposure simultaneously produce a meaningful altered-state experience and a stronger biological window for subsequent change?

We don't yet know.

What Does Comparative Research Say?

This is where the literature becomes interesting.

Some research has found little difference in eventual response or remission between IV racemic ketamine and intranasal esketamine.

A 2025 systematic review and meta-analysis of direct comparative studies found that pooled response and remission rates numerically favored IV ketamine but did not reach statistical significance. The evidence was almost entirely observational.

But that isn't the whole picture.

Several studies have found faster improvement with IV ketamine.

A 2023 observational study found similar eventual response and remission rates but significantly fewer treatments were required to achieve remission with IV ketamine.

And a larger 2025 naturalistic study of patients with severe treatment-resistant depression found something stronger.

Among 153 patients, those receiving IV racemic ketamine showed significantly greater reductions in depressive symptoms than those receiving intranasal esketamine from treatments three through eight.

By the eighth treatment, average symptom reduction was approximately 49% with IV ketamine versus 40% with intranasal esketamine.

The IV group also demonstrated statistically significant improvement earlier in treatment.

These findings are consistent with what some clinicians observe in practice.

But they remain observational.

Patient selection, clinical environment, treatment protocols and other variables may influence the result.

A definitive large randomized head-to-head comparison remains an important missing piece.

Indeed, a major comparative-effectiveness trial protocol published in 2026 is specifically designed to address the question of IV ketamine versus intranasal esketamine.

The debate isn't over.

It is actively being studied.

Why Some Studies May Find Similar Outcomes

This raises an important methodological question.

If two treatments produce similar depression-scale scores at a particular endpoint, does that mean the treatments themselves are equivalent?

Not necessarily.

Two interventions could eventually produce similar average symptom scores while differing in:

speed of response,

number of treatments required,

acute subjective experience,

pharmacokinetics,

tolerability,

durability,

patient preference,

cost,

or what happens between treatments.

Outcome measures matter.

Timing matters.

Patient selection matters.

Treatment environment matters.

And the question researchers choose to measure matters.

This doesn't invalidate studies finding similar outcomes.

It tells us what those studies can—and cannot—answer.

Bioavailability Is Not the Whole Story

It would be equally simplistic to argue:

IV has essentially complete bioavailability, therefore IV must always produce the best clinical outcome.

Biology rarely behaves so neatly.

Ketamine produces active metabolites.

Different routes change metabolite exposure.

Different patients metabolize drugs differently.

And therapeutic response emerges from interactions among pharmacology, psychology and environment.

Bioavailability gives IV an important pharmacokinetic advantage.

It does not, by itself, settle the entire therapeutic question.

A Route Comparison

This table describes evidence and regulatory context. It is not a dosing guide.

So Is IV Better?

For racemic ketamine, IV remains the gold-standard administration route in psychiatry.

That conclusion can coexist with scientific uncertainty.

It does not mean every patient should receive IV ketamine.

It does not mean Spravato is ineffective.

It does not mean every comparative study finds IV superior.

And it does not establish that greater psychedelic intensity automatically produces greater therapeutic benefit.

What it means is that IV combines several characteristics that remain difficult to reproduce simultaneously through other routes:

direct delivery

essentially complete bioavailability

precise control

predictable exposure

continuous medical observation

and the deepest evidence base for racemic ketamine in psychiatric treatment.

Whether IV also possesses additional therapeutic advantages because of the altered state it can produce—or because of differences in biological exposure—is a more interesting and still unresolved question.

What We Know

IV administration remains the reference or gold-standard route for off-label racemic ketamine treatment in psychiatry.

IV racemic ketamine has an extensive evidence base supporting rapid antidepressant effects, particularly in treatment-resistant depression.

IV administration provides direct systemic delivery and precise control over drug administration.

Intranasal esketamine is a distinct drug product with FDA-approved psychiatric indications and a REMS-supervised treatment model.

Intranasal racemic ketamine is not equivalent to Spravato.

Oral and sublingual ketamine have different pharmacokinetics and a less mature psychiatric evidence base.

Recent observational comparisons have sometimes found faster—and in some studies greater—symptom improvement with IV ketamine than intranasal esketamine.

But pooled comparative evidence has not yet established universal IV superiority.

What We Don't Know

We do not know exactly how much of ketamine's therapeutic effect comes from the acute altered state versus downstream pharmacological effects.

We do not know whether deeper dissociation or mystical experience directly improves clinical outcomes.

We do not know whether higher therapeutic ketamine exposure produces greater clinically meaningful neuroplasticity.

We do not know whether biological plasticity can be reliably measured in a way that predicts an individual patient's recovery.

We do not yet have enough high-quality head-to-head randomized evidence comparing IV racemic ketamine with intranasal esketamine.

And we do not know whether differences attributed to route sometimes reflect differences in setting, monitoring, preparation and psychological support instead.

These are not minor details.

They may be part of the treatment.

The Question That Remains

The route of administration can sound like a technical detail.

It isn't.

Route changes how the drug reaches the body.

It changes absorption.

It changes timing.

It changes predictability.

It changes monitoring.

It can change the treatment environment.

And it may change the altered state itself.

IV ketamine remains the gold-standard route for off-label racemic ketamine treatment in psychiatry.

But perhaps the most interesting question now lies beyond pharmacokinetics.

Ketamine appears capable of producing two remarkable phenomena within a relatively short period:

an extraordinary change in conscious experience,

and biological processes associated with the brain's capacity for change.

We still don't fully understand how those phenomena relate to each other.

Perhaps they are largely independent.

Perhaps the altered state is simply evidence that enough drug reached the brain.

Or perhaps the experience and the biological window interact in ways our current clinical trials aren't designed to capture.

If ketamine can temporarily change both how the brain functions and how a person experiences themselves, which part is actually doing the healing?

Disclosure

The founder and publisher of The Brazen Word is also a founder of Ketamine Lounge, which provides medically supervised IV ketamine treatment.

Observations attributed to Ketamine Lounge in this article reflect experience within that treatment environment and patient feedback. They are explicitly distinguished from findings established through controlled research.

The hypothesis that greater therapeutic ketamine exposure may produce greater clinically meaningful neuroplasticity has not been established by Ketamine Lounge or by current clinical evidence.

Editorial Note

The Brazen Word distinguishes between published evidence, clinical-environment observations and hypotheses generated from those observations.

The description of IV ketamine as a gold-standard route refers specifically to off-label racemic ketamine administration in psychiatric practice and its established evidence base. It should not be interpreted as a recommendation that IV ketamine is appropriate for every patient.

Safety Note

Ketamine and esketamine are Schedule III controlled substances and can produce sedation, dissociation, changes in blood pressure and other adverse effects. Different formulations and routes carry different monitoring considerations.

FDA has specifically warned about risks associated with compounded ketamine products used for psychiatric disorders without appropriate medical monitoring.

Medical Disclaimer

This article is provided for educational and informational purposes only and does not constitute medical advice, diagnosis or treatment. Decisions involving ketamine or esketamine should be made with appropriately qualified healthcare professionals after individualized medical and psychiatric evaluation.