The UK's National Institute for Health and Care Excellence (NICE) has rejected low-dose ketamine for treatment-resistant depression, citing inadequate trial evidence. The appraisal, published in draft guidance, concluded that existing studies were too small, too short, and too inconsistent in dosing to justify NHS commissioning. For the roughly one-third of patients who do not respond to standard antidepressants, the ruling closes off a potential avenue—at least within the public health system—while private clinics continue to offer the drug off-label.

NICE Rejects the Trials, Not the Drug

Ketamine's off-label use for depression has risen sharply since around 2019, fueled by a series of small but dramatic open-label studies showing rapid reductions in suicidal ideation and depressive symptoms. However, NICE's systematic review, which examined eight randomised controlled trials involving low-dose intravenous ketamine, found that none met the agency's threshold for reliability. Most trials enrolled fewer than 50 participants, follow-up rarely exceeded four weeks, and placebo control was often poor due to ketamine's dissociative effects.

The committee noted that dosing protocols varied widely—some studies used 0.5 mg/kg infused over 40 minutes, others used different rates or subcutaneous routes—making it impossible to determine an optimal regimen. "The evidence does not support a recommendation for routine use in the NHS," the draft guidance states. Importantly, NICE did not rule out future approval if larger, more rigorous trials emerge. The rejection is of the current evidence base, not the drug itself.

This nuance is often lost in media coverage. Ketamine's potential remains real; the question is whether it has been proven enough for a public health system that must weigh cost and safety alongside efficacy. NICE's bar for evidence is deliberately high, especially for treatments with known risks—including dissociation, blood pressure spikes, and potential bladder toxicity with repeated use.

Dr. Rupert McShane, a psychiatrist at Oxford Health NHS Foundation Trust who has conducted several ketamine studies, commented: "The evidence is not definitive, but it is suggestive. For a patient who is suicidal and has tried everything, a treatment with a 50% response rate in small trials is better than nothing." Others counter that the trials, though imperfect, are no worse than those that supported other psychiatric interventions, such as certain antipsychotics or mood stabilizers. But NICE's role is to set a consistent standard, and here the trials fell short.

Why Treatment-Resistant Depression Needs New Options

Treatment-resistant depression (TRD) is defined as failure to respond to at least two adequate trials of antidepressants from different classes. It affects roughly 30% of people with major depressive disorder, translating to hundreds of thousands of patients in the UK alone. For these individuals, the standard algorithm offers limited choices: augmentation with another drug, switching to a different class, or electroconvulsive therapy (ECT), which remains effective but heavily stigmatized. Oral augmentation strategies—adding lithium, atypical antipsychotics, or thyroid hormone—have modest efficacy and often bring side effects like weight gain or metabolic changes. A 2023 Cochrane review found that augmentation with a second antidepressant added little benefit over placebo. Patients and clinicians alike describe feeling stuck in a narrow pipeline, cycling through drugs that barely move the needle.

Esketamine (Spravato), a nasal spray derived from ketamine, was approved by the European Medicines Agency in 2019 and is available through a restricted NHS program, but only for patients who have failed at least two antidepressants and only in specialist centres. Access is limited by geography and capacity; many patients wait months for an assessment. Low-dose racemic ketamine, which is cheaper and can be infused in outpatient settings, seemed like a more scalable option.

The unmet need is acute. A 2022 survey by the charity Mind found that nearly half of people with depression had tried three or more antidepressants without relief. Some turn to private clinics, paying hundreds of pounds per session, or to online providers offering ketamine lozenges or troches with uncertain quality control. The NICE decision does not stop these practices, but it does deny NHS patients an option that many clinicians believe could help.

The Evidence Gap That Divided Experts

The systematic review underpinning NICE's decision included only eight randomised trials, with a total of around 400 participants. Outcome measures varied: some used the Montgomery-Åsberg Depression Rating Scale (MADRS), others the Hamilton Depression Rating Scale (HAM-D), and a few the Quick Inventory of Depressive Symptomatology (QIDS). This heterogeneity made meta-analysis difficult. When pooled, the effect size for ketamine over placebo was moderate at 24 hours but diminished by day seven, and no trial reported data beyond four weeks.

Long-term safety data are almost nonexistent. Ketamine's potential for bladder toxicity—interstitial cystitis-like symptoms—has been documented in recreational users, but the risk at low, intermittent doses for depression is unknown. Cognitive effects, including memory impairment, have been reported in some studies but not systematically assessed. NICE flagged these gaps as critical.

Despite these limitations, some experts argue that equipoise still exists. McShane and others point out that the placebo response in depression trials is notoriously high—often 30–40%—which can obscure real drug effects in underpowered studies. The disagreement is not about whether ketamine works, but about what level of proof is sufficient for a public health system. NICE's cautious approach may protect patients from unproven harms, but it also delays access for those who might benefit. The gap between clinical experience and trial evidence is wider for ketamine than for almost any other psychiatric drug.

How the US and Australia Compare

In the United States, intravenous ketamine for depression is offered off-label by thousands of clinics, with costs typically ranging from several hundred to nearly a thousand dollars per infusion. Insurance coverage is patchy: some plans cover it after prior authorization, others explicitly exclude it. The American Psychiatric Association has not issued a formal guideline, though several expert consensus statements support its use in TRD. There is no national registry to track outcomes or adverse events, making real-world evidence difficult to gather.

Australia's Therapeutic Goods Administration (TGA) allows prescribing of ketamine for depression under the Authorised Prescriber scheme, which requires individual approval for each patient. This creates a bureaucratic hurdle but also enables some data collection. A 2024 audit of Australian prescribers found that response rates in routine practice were similar to those in clinical trials, but follow-up was often incomplete.

Neither country has the centralized appraisal system that the UK does. NICE's ability to say no—and to demand better evidence—is a strength of the NHS, but it also means that promising treatments can languish in regulatory limbo. The contrast highlights a fundamental tension: in the US and Australia, patients can access ketamine more easily, but with less oversight and greater financial burden. In the UK, the system prioritizes equity and evidence, sometimes at the cost of speed.

The NICE decision may also influence other countries' regulators. The European Medicines Agency has approved esketamine but not racemic ketamine; several European countries are watching the UK appraisal closely. If NICE ultimately reverses its position after larger trials, it could set a precedent for wider adoption. For now, the evidence gap remains a chasm.

Ketamine’s Uncomfortable History in Psychiatry

Ketamine's journey from recreational drug to psychiatric treatment has been anything but smooth. First synthesized in 1962, it gained popularity as a dissociative anesthetic in veterinary and human medicine, and later as a club drug known as "Special K." Its potential for abuse and its psychotomimetic effects—hallucinations, out-of-body experiences—made psychiatrists wary. Early open-label studies in the 2000s showed dramatic response rates, sometimes within hours, which seemed almost too good to be true.

The placebo response in depression trials is notoriously high, and ketamine's dissociative effects make blinding nearly impossible. Patients and clinicians can often tell who received active drug, skewing results. This is a methodological nightmare that small trials cannot overcome. Industry-funded trials of esketamine, which is less dissociative than racemic ketamine, have been criticized for similar blinding issues, though they were larger and longer.

A 2024 meta-analysis by researchers at King's College London found that when only trials with adequate blinding were considered, the effect size of ketamine dropped by half. This does not mean ketamine is ineffective, but it does suggest that early enthusiasm may have been inflated. NICE's skepticism is partly a response to this history: psychiatry has been burned before by treatments that looked promising in small studies but failed in larger ones.

The debate over whether low-dose ketamine is truly sub-anesthetic adds another layer. At 0.5 mg/kg, many patients experience mild dissociation, blurred vision, or dizziness—effects that are not necessarily therapeutic but are difficult to separate from the drug's antidepressant action. Some researchers argue that the dissociative experience itself may be part of the mechanism, akin to psychedelic-assisted therapy, while others see it as an unwanted side effect that complicates trial design.

What This Means for Future Trial Design

NICE's draft guidance includes a clear call for better trials: multi-site, randomised, double-blind, with at least 12 weeks of follow-up and a standardized dosing protocol. The agency also suggests using an active comparator, such as ECT or an intranasal esketamine arm, to contextualize efficacy. Patient-reported outcomes, like the Patient Health Questionnaire (PHQ-9), should supplement clinician-administered scales to capture real-world functioning.

Funding is a major obstacle. Ketamine is off-patent and inexpensive, so there is little commercial incentive for pharmaceutical companies to sponsor large trials. The UK's National Institute for Health and Care Research (NIHR) has funded some smaller studies, but a definitive trial would likely cost several million pounds. Charities like the Wellcome Trust and the Medical Research Council have shown interest, but no large-scale trial is currently underway.

Some researchers advocate for pragmatic trials that randomize patients to ketamine versus treatment-as-usual in real-world clinics, rather than the artificial conditions of an RCT. Such trials can include diverse populations and longer follow-up, but they introduce confounding variables. NICE has historically preferred explanatory trials, but the agency has also accepted pragmatic evidence in other areas, such as weight loss surgery.

The ideal trial would also include biomarkers—perhaps EEG or blood-based measures—to identify which patients are most likely to respond. A 2025 pilot study suggested that a specific EEG pattern predicted response to ketamine with 80% accuracy, but the finding needs replication. Personalizing ketamine treatment could improve its risk-benefit ratio and make a positive NICE appraisal more likely.

Patients Left in a Regulatory Limbo

While NICE deliberates, patients in the UK are not waiting. Private clinics offer intravenous ketamine infusions for several hundred pounds per session, typically as a course of six infusions over two to three weeks. Some also prescribe sublingual or nasal formulations for at-home use, though the evidence for these routes is even thinner. Costs are prohibitive for most people; a full course can easily exceed a few thousand pounds.

Patient advocacy groups, such as the Ketamine for Depression UK network, have pushed for pragmatic trials within the NHS. They argue that the current evidence, while imperfect, is sufficient for a conditional approval with mandatory data collection. "We are not asking for unrestricted access," one advocate said. "We want a system where patients can try ketamine under supervision and contribute to the evidence base."

Some NHS clinicians already prescribe racemic ketamine off-label, using individual funding requests that are often rejected. A 2025 survey by the Royal College of Psychiatrists found that 40% of consultant psychiatrists had considered ketamine for a patient, but only 15% had successfully obtained funding. The NICE decision may harden the position of local commissioning groups, making it even harder to get approval.

The risk of the NICE decision is that it drives treatment underground. Patients may seek out unregulated online providers, where quality control is nonexistent. A 2024 investigation by the BBC found several websites selling ketamine lozenges without a prescription, using misleading claims about safety and efficacy. The regulatory limbo does not eliminate demand; it simply redirects it to less safe channels.

Ultimately, the NICE appraisal reflects a broader tension in mental health care: the gap between what patients need, what clinicians believe, and what evidence can prove. Ketamine is not a miracle drug, but for some, it may be the only thing that works. Until the trials are done, that possibility remains tantalizingly out of reach for NHS patients.