What Side Effect Data Tells Us About Ketamine Dosing

The Study at a Glance

A new analysis published in Psychiatric Times (April 2026) examines the side effect profiles and discontinuation rates of NMDA receptor antagonists — a drug class that includes IV ketamine and the FDA-approved nasal spray esketamine (Spravato) — in patients with treatment-resistant depression (TRD). The authors, writing from a clinical perspective, argue that practitioners are moving too slowly when patients show inadequate responses or poorly tolerated side effects. Their core recommendation: use structured outcome measures like the PHQ-9, track adverse effects systematically, and be willing to adjust doses or switch agents sooner rather than waiting out prolonged trials that aren't working.

While the piece covers the broader NMDA antagonist landscape, its implications are especially relevant for anyone exploring or currently undergoing low-dose ketamine therapy — a context where dosing precision and side effect awareness are foundational to a good outcome.

What the Evidence Shows on Side Effects

Across clinical trials and real-world data, the most commonly reported side effects of ketamine and esketamine in TRD treatment include dissociation, dizziness, nausea, elevated blood pressure, and perceptual disturbances during or shortly after administration. These effects are generally transient — peaking within the first hour and largely resolving before patients are discharged from monitored settings. That said, the frequency and intensity of these effects vary meaningfully depending on dose, route of administration, infusion rate, and individual patient factors such as body weight, prior substance use history, and baseline anxiety levels.

Discontinuation rates in published trials have ranged widely, from roughly 10% to over 30% depending on the population studied, the agent used, and how discontinuation was defined. The Psychiatric Times analysis highlights that a meaningful proportion of patients who stop treatment do so not because of lack of efficacy, but because of side effects they found intolerable — a distinction that matters clinically, because it suggests some of those discontinuations might have been preventable with earlier dose adjustments or better pre-treatment preparation.

The authors also flag that many clinicians lack standardized protocols for documenting side effects longitudinally, making it difficult to identify patterns or intervene before a patient reaches the point of stopping treatment entirely.

Why This Matters Specifically for Low-Dose Ketamine

The framing of this analysis — optimize doses, switch sooner, track outcomes rigorously — aligns closely with the philosophy that already underpins responsible low-dose ketamine practice. But it adds nuance that patients and clinicians alike should take seriously.

First, the emphasis on dose optimization cuts both ways. In the low-dose context, practitioners often start conservatively to minimize dissociative side effects, particularly for patients with anxiety, trauma histories, or concerns about psychoactive experiences. This cautious approach is clinically defensible, but the Psychiatric Times authors are pointing to a real risk on the other end: undertreating out of excessive caution, or staying at a subtherapeutic dose too long without reassessing. The message isn't to rush upward on dosing — it's to be data-driven about whether the current dose is actually working, using structured tools like the PHQ-9 rather than relying solely on subjective patient report.

Second, the discontinuation data should prompt a harder look at how well patients are being prepared for the side effect experience before their first session. Dissociation, in particular, is frequently cited as a reason patients feel distressed during treatment — not because it's medically dangerous at low doses, but because they weren't adequately informed about what to expect. A patient who understands that mild perceptual changes are expected and temporary is far less likely to interpret those changes as a sign something is wrong, and far less likely to discontinue prematurely.

Third, the call for systematic side effect tracking is a practical gap in many outpatient ketamine programs. Standardized instruments exist for capturing dissociation severity (such as the CADSS) and blood pressure response, but they aren't universally used. Patients who receive treatment in settings that don't track these metrics longitudinally may not have the data necessary to identify trends — for instance, whether side effects are improving as their nervous system adapts, or whether a particular symptom is worsening and warrants a protocol change.

It's also worth noting what this analysis does not address: long-term safety beyond the acute treatment period. The field still lacks robust data on what happens to patients who remain on maintenance ketamine for years, particularly regarding any cumulative effects on urinary tract health, cognitive function, or psychological dependence at the doses used in clinical TRD protocols. The absence of data here isn't evidence of safety — it reflects the relative newness of widespread clinical use and a genuine need for longer-term observational research.

Practical Considerations for Patients and Caregivers

Before starting treatment: Ask your provider what side effects to expect, how they're monitored during sessions, and what the protocol is if you find a side effect intolerable. Understanding that dissociation is expected — and time-limited — can significantly reduce the distress it causes when it occurs.

During a treatment course: Keep a simple log of how you feel during and after sessions, including any side effects and their duration. This doesn't need to be elaborate — even a 1–10 rating of dissociation intensity and mood in the hours following treatment gives your provider useful information they may not otherwise have.

If you're not responding: The Psychiatric Times analysis reinforces that staying on an ineffective protocol out of hope or inertia isn't serving you. If you've completed an adequate initial course (typically six infusions for IV ketamine) without meaningful improvement on a structured scale like the PHQ-9, that's a data point — and a reason to have a frank conversation with your provider about whether dose, frequency, or modality should change.

On maintenance therapy: Discontinuation rates in TRD research are often measured over the acute treatment phase, but maintenance is where the real-world picture gets more complex. Patients who respond well often continue with less frequent treatments over months or years. The same principles apply: track outcomes, document side effects, and reassess periodically rather than continuing maintenance indefinitely without checking whether it's still doing what it was designed to do.

The full analysis is available via Psychiatric Times. It's a useful read for clinicians and well-informed patients alike — though its primary audience is practitioners, and some of the clinical language assumes familiarity with TRD treatment protocols.