Ketamine for OCD: Obsessions, Compulsions, and Evidence

Small studies show ketamine can reduce OCD symptoms quickly, sometimes within an hour or two of a single dose. That finding has now turned up in more than one controlled study, which makes it harder to wave away. But the human evidence is tiny, results have been inconsistent, and lasting benefit is far less certain than fast benefit.

The strongest OCD evidence involves racemic ketamine given by IV or injection, not Spravato. One small open-label study found almost no OCD response. Ketamine for OCD is off-label in the United States, and treatments with real evidence behind them remain much better studied.

OCD Evidence Is Different From Depression and Anxiety Evidence

Ketamine's rapid effect on depression is well documented. That doesn't establish an anti-OCD effect, and the distinction matters more than people expect.

DSM-5 doesn't group OCD with the anxiety disorders. It sits in its own category, obsessive-compulsive and related disorders. Research on ketamine therapy for anxiety doesn't transfer either.

Many people with severe OCD also have depression. If mood lifts, someone can feel better while their obsessions and rituals barely change. That's why OCD studies use direct measures like the Yale-Brown Obsessive Compulsive Scale, usually shortened to Y-BOCS. Improvement on a depression scale isn't evidence that OCD improved.

What Does the Research Overall Show?

A 2026 scoping review mapped the field and found 21 studies. Five were preclinical, meaning animal or laboratory work. Sixteen were clinical investigations in people.

Sixteen sounds like a lot. It isn't. Those sixteen break down into 4 randomized trials, 3 open-label studies, 2 case series, and 7 case reports. Two of the randomized trials stopped after enrolling almost nobody.

So the honest summary is this. There's a repeatable signal that ketamine can move OCD symptoms in some people, and it can happen fast. But there's no large, replicated, long-term randomized evidence base, and no pooled success rate from this literature would mean much.

The 2013 Randomized Ketamine Trial

This is the study everything else gets measured against. Rodriguez and colleagues randomized 15 drug-free adults with primary OCD and near-constant obsessions, defined as more than eight hours a day. Each received one 40-minute IV infusion of ketamine at 0.5 mg/kg and one of saline, at least a week apart.

Then something unexpected happened. Ketamine's effects outlasted the one-week washout, so people who got it first hadn't returned to baseline before their second infusion. This carryover effect cuts both ways. It suggests real durability in some participants, and it also broke the crossover design, so data from the two phases couldn't be combined.

The efficacy analysis therefore rests on the first phase alone: 8 people who received ketamine first and 7 who received saline first. Obsession severity improved more with ketamine, and the difference was still detectable at day 7. At one week, 4 of those 8 met the predefined threshold of at least a 35 percent Y-BOCS reduction. None of the 7 saline participants did.

Half of eight is four people. That's the entire basis of the widely repeated 50 percent figure, and it isn't a rate you should expect for yourself.

A Newer Controlled Trial Found Another Signal

Beaglehole and colleagues published a second controlled trial online in late 2024, appearing in the Journal of Psychopharmacology in 2025. Participants were adults with severe treatment-resistant OCD, with average starting Y-BOCS near 30.

This was a double-blind three-way crossover using intramuscular injections: ketamine at 0.5 mg/kg, ketamine at 1.0 mg/kg, and fentanyl 50 micrograms as a psychoactive control. An active control makes blinding harder to see through than saline.

Y-BOCS scores fell more after both ketamine doses than after fentanyl. The authors found a significant treatment effect, although categorical response rates didn't increase with the higher dose. Changes peaked at one to two hours, and separation from fentanyl held out to about 168 hours.

Keep the scale in view. Twelve people were randomized, 10 completed all treatment arms, and two withdrew after struggling to tolerate the dissociative effects associated with the higher dose. This is another small controlled signal, not a large replication.

Why Some Ketamine Studies Have Been Negative

Bloch and colleagues ran an open-label study in 2012, giving IV ketamine at 0.5 mg/kg over 40 minutes to 10 adults with treatment-refractory OCD.

None of the 10 met the study's OCD response criterion during the first three days. Symptoms did shift measurably, but by less than 12 percent, which most people wouldn't notice.

Those same infusions did something else. Seven participants had comorbid depression, and 4 of those 7 had an antidepressant response. Same drug, same dose, two very different outcomes in the same people.

Does Ketamine Affect OCD Independently of Depression?

Those two studies point opposite ways, and both are informative. Rodriguez enrolled medication-free people selected for OCD, and depression scores didn't explain the anti-obsessional finding. Bloch showed the reverse, with mood improving while OCD scores stayed put.

The two symptom domains can apparently move independently. That isn't the same as proving separate biological mechanisms, and nobody has shown that.

Obsessions and Compulsions Are Not the Same Outcome

Obsessions are intrusive thoughts, images, or urges. Compulsions are the repetitive behaviors or mental acts done in response. A treatment could affect one more than the other.

The acute research leans heavily toward obsessions, for a practical reason the Rodriguez team stated plainly. Participants were lying down and attached to monitoring equipment during the infusion, so compulsions requiring movement were physically constrained. Their rapid measure, a visual analog scale, rated obsessions only.

Y-BOCS totals were tracked over the following days, and obsession and compulsion subscales weren't reported separately. A fast drop in intrusive thoughts isn't proof that rituals eased just as quickly.

How Quickly Can OCD Symptoms Change?

Faster than anything in standard OCD pharmacotherapy, in the studies where it worked at all. SSRIs generally take weeks to months. Changes have been recorded during the infusion itself, and the largest Y-BOCS changes in the intramuscular trial came at one to two hours.

Rapid onset says nothing about whether a benefit stays.

How Long Can the Effect Last?

Each study answers this differently. In Rodriguez, effects were still measurable at one week in some participants, and the carryover suggests longer in a few. In the intramuscular trial, separation from the control held to roughly 168 hours. In Bloch, there was no meaningful OCD response to sustain.

Small controlled studies have seen effects lasting several days to about a week in some people. What happens past that point is largely unstudied.

Does Repeated Ketamine Work Better Than One Treatment?

The evidence here is weaker than the question deserves.

A 2020 chart review followed 14 adults with SRI-resistant OCD through repeated IV infusions, averaging about 5.4 each. One had a dramatic response, with Y-BOCS falling to zero. Two had partial responses. The other 11 showed no clinical improvement.

The group's average Y-BOCS did drop significantly. That statistic and those individual outcomes tell different stories, and the individual outcomes matter more. More infusions are not a demonstrated fix for the durability problem, and no protocol here is a recommended schedule.

What Does the New Oral Ketamine Study Tell Us?

In 2025, the same New Zealand group published a six-week open-label extension using oral ketamine. Of the 10 OCD participants who finished the injection trial, 8 continued and 5 completed all six weeks. Doses were individualized, with no placebo or control group.

Here's the part that decides what it means. Y-BOCS had already fallen from about 30 at the original baseline to about 10.5 when oral dosing began. It finished the extension around 9.

Symptoms were already low before the oral phase started. The study supports a preliminary maintenance signal and nothing more. The authors state directly that they couldn't confirm whether this regimen would treat someone still symptomatic.

What About Intranasal Ketamine?

Racemic ketamine sprayed into the nose is not the same product as Spravato, and the two aren't interchangeable.

One randomized trial compared intranasal ketamine against intranasal midazolam in OCD. It was terminated for poor tolerability and low enrollment, with 2 participants total, and neither met response criteria. A separate intranasal trial at McLean Hospital stopped for recruitment difficulty after enrolling 1 person.

Neither result tells you whether intranasal ketamine works. Two people can't answer that in either direction. What these trials do show is that the route itself was hard to tolerate.

What About Spravato or Esketamine for OCD?

Spravato is not FDA approved for OCD. Its approved uses are treatment-resistant depression in adults, and depressive symptoms in adults with major depressive disorder who have acute suicidal ideation or behavior. Treatment-resistant OCD is a different clinical concept, and it doesn't qualify anyone under a depression indication. Our guides on Spravato treatment and IV ketamine versus Spravato cover the differences.

OCD-specific esketamine evidence is thin. A 2026 prospective case series followed 8 adults with severe treatment-resistant OCD who also had a severe depressive episode. They received intranasal esketamine at 56 to 84 mg on the standard depression schedule over 12 weeks, with no control group. The report describes intranasal esketamine rather than naming a brand.

Depression improved substantially, with MADRS down about 49 percent. OCD improved less and less consistently, with Y-BOCS down about 30 percent, and gains emerging more often between weeks 8 and 12. Four of the 8 met OCD response criteria.

With severe comorbid depression and no control condition, this can't establish an OCD-specific effect. The authors say so themselves.

Can Ketamine Be Combined With ERP?

ERP, or exposure and response prevention, is the behavioral therapy with the strongest track record in OCD. Researchers have wondered whether the hours after ketamine might be a useful window for it, drawing on ideas about learning and neuroplasticity.

One open-label pilot tested that. Ten unmedicated OCD outpatients started, and 8 completed and were analyzed. Each received a single IV infusion, then 10 one-hour exposure sessions across two weeks. Five of the 8, or 63 percent, met the response threshold at week 2, with improvement still measurable at week 4.

There was no ketamine-only arm, no ERP-only arm, and no placebo. The study can't separate what ketamine did from what ERP did. It shows the combination is feasible and worth testing. It doesn't show that ketamine makes ERP work better, and ketamine-assisted ERP isn't an established protocol.

Is Ketamine Better Than ERP or Standard OCD Medication?

There's no evidence establishing that, because the head-to-head trials don't exist.

ERP and SSRIs have been studied in far larger and longer trials, with clomipramine and several augmentation strategies behind them for resistant cases. Setting a percentage from an eight-person analysis against a meta-analysis of ERP isn't a comparison at all. Ketamine isn't a replacement for ERP.

What Do Current OCD Guidelines Say About Ketamine?

Guidelines agree on the shape of things: ERP and SSRIs remain first-line. Ketamine appears late, in discussions of treatment-resistant OCD, because the studies are small and effects may be transient.

The Indian Psychiatric Society's 2025 update, published in 2026, lists ketamine among pharmacological augmenting agents at 0.5 to 1 mg/kg by infusion. It assigns level 3 evidence, the lowest tier, and places it third-line, because two small single-dose randomized trials showed acute improvement while consistent long-term evidence is missing.

The CANMAT and ICOCS 2025 international guidelines take a similar position. Ketamine may be considered in highly treatment-resistant situations where rapid response particularly matters, with limited efficacy data and transient effects emphasized.

Is Ketamine FDA Approved for OCD?

No. Generic ketamine injection is approved as an anesthetic and nothing more, and current labeling never mentions obsessive-compulsive disorder. Spravato is approved only for the depression indications described earlier.

Using ketamine for OCD is off-label. That's legal and common throughout psychiatry, and it doesn't mean improper or unsafe. It does mean no regulator has reviewed evidence for this use. Anesthetic approval says nothing about whether ketamine helps OCD.

Who Has Actually Been Studied?

Very few people, and not the same kinds of people.

Rodriguez enrolled medication-free adults with near-constant obsessions. Beaglehole enrolled severely ill, treatment-resistant participants who stayed on existing medication and therapy. Bloch enrolled treatment-refractory patients, mostly with comorbid depression. Three different populations, which may help explain why results conflict. That's a plausible explanation, not a proven one.

Pediatric evidence is minimal, limited to two small uncontrolled adolescent case series. One gave repeated infusions to four teenagers. Three improved with benefit at two months. The youngest developed prolonged psychotic symptoms after the third infusion, which the authors described as ketamine-induced psychosis. Treatment was stopped, an antipsychotic was started, and the symptoms resolved within days. The other series gave a single infusion to five adolescents, with short follow-up. A single case can't tell you how often that happens, and neither series establishes the efficacy or safety of ketamine for routine OCD treatment in adolescents.

What Are the Biggest Limits of the Evidence?

Naming the gaps beats saying more research is needed.

Randomized samples in the single digits and low teens
A carryover effect that compromised the 2013 crossover design
Two intranasal trials terminated at 2 and 1 participants
Different routes, doses, and comparators, with medication-free participants in one trial and medicated participants in another
Acute measures focused on obsessions rather than total OCD severity
Inconsistent definitions of treatment resistance, and heavy comorbidity in several samples
Almost no controlled long-term follow-up, and little maintenance evidence
No way to predict who responds, with esketamine data limited to uncontrolled reports
No adequate comparison against ERP or established medication
Case reports making up nearly half the clinical literature, and very limited pediatric data

What Should You Ask a Ketamine Provider About OCD?

These questions separate careful clinics from casual ones.

How much experience do you have treating OCD specifically?
Are you treating my OCD, or my depression?
What evidence supports the route you're recommending?
Will you measure my OCD with the Y-BOCS or another validated scale?
How will we tell depression changes from OCD changes?
What role should ERP keep playing?
What evidence supports repeated or maintenance dosing?
How will you decide whether it's helping enough to continue?

Finding a Provider for Treatment-Resistant OCD

A clinician taking OCD seriously should be comfortable with the diagnosis, with what treatment resistance means in OCD, and with the central role of ERP. They should track symptoms with a validated OCD measure and be candid that this treatment is off-label with limited evidence.

Our guides on choosing a ketamine clinic and who is a good candidate cover what to look for, and who should not get ketamine therapy covers screening concerns. For side effects and interactions with what you already take, see is ketamine therapy safe and ketamine and medications. You can also search clinics near you.