Ketamine for Chronic Pain: Which Conditions May Benefit?
Ketamine can reduce pain for some people with chronic pain, but the answer depends heavily on which condition is being treated. Historically, complex regional pain syndrome has had the strongest condition-specific support. Even there, current evidence remains uncertain. For most other chronic-pain disorders, results are weaker, shorter-lived, or contradictory.
The overall certainty of the evidence is low. A large 2025 Cochrane review could not establish that ketamine meaningfully reduces chronic pain intensity. That uncertainty does not establish that ketamine has no benefit. Treating pain with ketamine is off-label, and pain protocols often look nothing like the psychiatric infusions most ketamine clinics run.
Chronic Pain Isn't One Diagnosis
That heading is the most important thing on this page. Chronic pain is a category, not a disease, and the conditions inside it behave differently.
CRPS, peripheral neuropathic pain, spinal cord injury pain, fibromyalgia, phantom limb pain, postherpetic neuralgia, and chronic back pain all sit under that umbrella. Their mechanisms differ, and so do their responses to ketamine.
A positive CRPS trial doesn't prove ketamine helps fibromyalgia. A neuropathic-pain meta-analysis doesn't automatically extend to chronic back pain. When a clinic says ketamine treats chronic pain, ask which chronic pain, and what evidence exists for that diagnosis.
What Does the Research Overall Show?
The most rigorous recent answer comes from a Cochrane review published in August 2025, with evidence current through June of that year. It covered adults with chronic non-cancer, non-headache pain lasting at least three months.
It found 67 randomized trials with 2,309 participants. Ketamine was the drug studied in 39 of them. Only 28 studies could be pooled statistically at all.
The pooled comparison of IV ketamine against placebo showed no clear reduction in pain intensity in the immediate term, the short term, or the medium term. Certainty was rated low to very low throughout. IV ketamine may increase the risk of adverse events.
Notice how thin those pooled comparisons are. The immediate-term estimate rests on 3 studies and 173 participants. The medium-term estimate rests on a single study with 19 people.
That's the honest picture. Not evidence that ketamine fails, but a body of research too small and too inconsistent to settle the question.
Complex Regional Pain Syndrome: The Strongest Signal, Still Uncertain
Among chronic-pain conditions, CRPS has historically received the most support for ketamine treatment. But the supporting evidence is still limited.
A 2018 consensus guideline from three American pain societies gave CRPS a grade B recommendation, based on moderate evidence with low to moderate certainty. That was the strongest grade any condition received, and it's now eight years old.
The closest look at CRPS specifically came in 2023, when a Cochrane overview assessed the systematic reviews of CRPS treatments. It found no high-certainty evidence for any therapy. For ketamine it judged the evidence very uncertain. IV ketamine did beat placebo right after treatment, but at medium-term follow-up no between-group benefit was established, resting on 2 trials and 79 people.
That overview also warned that non-Cochrane CRPS reviews were generally of low methodological quality and shouldn't be relied on for an accurate summary. That matters for weighing the reviews that came after.
A 2024 meta-analysis of CRPS drug treatments found a statistically significant advantage for ketamine beyond one month, with a pooled mean difference of 0.78 and low-certainty evidence. It found no significant short-term benefit and more adverse events.
A 2025 review described IV ketamine as producing strong short-term analgesia, while flagging small samples, variable protocols, and missing long-term data.
Here's the number that matters most. That 2025 review covered 45 CRPS trials with 2,125 patients, but only 3 of those trials studied ketamine, totaling about 80 participants. Reviews of all CRPS treatments get quoted as though every patient received ketamine. They didn't.
None of this means ketamine does nothing for CRPS. It means the signal is real enough to keep studying and too uncertain to promise.
How Long Can CRPS Relief Last?
The familiar claim is 12 weeks. It traces to the 2018 guideline, and it deserves a closer look.
The largest trial behind it randomized 60 CRPS patients to a 4.2-day continuous infusion of S-ketamine or placebo. Pain scores across the 12-week study period were significantly lower with ketamine. The widest gap came at the end of week 1, around 2.7 on a 0 to 10 scale versus 5.5 on placebo.
By week 12, the difference between groups was no longer statistically significant. The paper reports a p value of 0.07 at that point. The same trial found no functional improvement.
So the accurate statement is that controlled studies detected benefit for several weeks, with separation from placebo fading by the end of a 12-week follow-up. That isn't three guaranteed months of relief.
What About Neuropathic Pain?
Three reviews of this literature reach three different answers, and the reasons are worth seeing.
A 2022 meta-analysis of 18 randomized trials with 706 participants found a significant pain reduction one week after treatment ended, averaging 2.14 points. Certainty was rated low, and psychedelic side effects were more common with ketamine.
A 2024 review focused on multifactorial neuropathic pain reached the opposite conclusion. Low-dose ketamine showed no significant advantage over placebo for pain or function, and no dose could be identified as supported.
A 2026 meta-analysis reached a more favorable short-term conclusion. In 6 small trials totaling 135 people, IV ketamine raised the likelihood of achieving at least 50 percent pain reduction compared with placebo, roughly a 2.8-fold difference. Adverse effects were about 3 times more frequent. The authors still emphasized small samples, short follow-up, and heterogeneous methods.
That 2026 paper is a new analysis, not a batch of new trials. Reviews like these differ in which populations they include, which routes they allow, which outcomes they count, and when they measure. A responder rate and an average pain score can move in different directions from the same evidence.
The fair conclusion is that a short-term analgesic signal exists in neuropathic pain, while its size, durability, and generalizability stay uncertain.
Spinal Cord Injury Pain
The 2018 guideline gave spinal cord injury pain a grade C recommendation, based on weak, low-certainty evidence for short-term improvement. One study showed benefit during the infusion and for up to two weeks afterward.
Nothing published since has changed that picture. CRPS findings shouldn't be read across to this condition, and long-term benefit hasn't been shown.
Ketamine for Fibromyalgia
A 2024 systematic review found only 6 published articles, covering 115 patients in total. It searched a single database, through 2021. Doses ran from 0.1 to 0.5 mg/kg, mostly intravenous, with one study using subcutaneous injection.
Most of the short-term studies reported good responses. The one study that followed people for eight weeks did not.
Side effects were common. They appeared during the infusion and faded within minutes of stopping it.
The 2018 guideline placed fibromyalgia among the conditions with weak or no evidence for even immediate improvement.
Short-term analgesia has been observed. Evidence that it persists is weak. A drop in pain during an infusion isn't the same as durable clinical benefit.
What About Chronic Back Pain and Other Pain Conditions?
For chronic low-back and spinal pain, phantom limb pain, postherpetic neuralgia, and ischemic pain, the 2018 guideline found weak or no evidence supporting even immediate improvement.
Excluding CRPS, it found no evidence at all supporting intermediate or long-term improvement in any condition.
No newer controlled trial has changed that. The research needed to answer these questions largely hasn't been done.
How Quickly Can Ketamine Reduce Pain?
Pain trials often detect an effect during the infusion itself or within hours of it.
But timing depends on the protocol. Some CRPS studies used continuous infusions running for days, so how fast means something different than for a single short session.
An immediate analgesic effect tells you the drug is doing something while it's present. It says nothing about what happens once it clears.
How Long Does Pain Relief Last?
This is the question the evidence answers worst.
Separate two things. Immediate analgesia during and shortly after an infusion is reasonably well documented. Persistent benefit after the drug is gone is far less certain.
CRPS has the clearest evidence of benefit outlasting the infusion, and even there the separation from placebo faded by week 12 in the largest trial.
For most other conditions the evidence weakens as follow-up lengthens. Trials are short, and many end before they could detect whether anything lasted.
Does Repeated Treatment Work Better Than One Infusion?
Pain clinics commonly use multi-day or repeated protocols. That's a practice pattern, not a proven schedule.
The 2018 guideline did find a dose-response signal. Higher doses over longer periods were associated with longer relief. One analysis suggested infusions running more than 10 hours had a high probability of producing more than 50 percent relief lasting beyond 48 hours.
That's a correlation drawn from a small and varied literature. It isn't the same as knowing the optimal number of treatments, the right spacing, or when to stop.
No standard induction series exists for chronic pain. The six-infusion convention some psychiatric clinics use comes from depression research and has no bearing here.
Chronic Pain Infusions Can Look Very Different From Depression Infusions
This matters if you're calling clinics.
Psychiatric ketamine is typically a 40-minute infusion at around 0.5 mg/kg. Chronic-pain research protocols have often used much longer infusions, sometimes running continuously for days, with greater total exposure.
Those are research protocols rather than recommendations, described here only to show how far apart the two treatments can be.
The difference affects monitoring, the setting required, and the likelihood of side effects. It also means evidence from one doesn't transfer to the other. Our guide on IV ketamine versus Spravato covers how delivery methods differ.
Is There an Established Ketamine Dose for Chronic Pain?
No. No single regimen has been established across chronic-pain conditions.
The 2018 guideline examined dose-response relationships but described wide variation in actual practice. A 2026 scoping review searching for published guidelines on ketamine in chronic non-cancer pain found only three documents that qualified, meeting between 34 and 76 percent of national guideline standards.
Its conclusion was that the field still lacks a consistent, standard approach.
What About Oral Ketamine for Chronic Pain?
A 2025 systematic review looked for randomized studies of oral ketamine and found only 6, spread across very different pain settings including acute and procedural pain. Its inclusion criterion was any type of pain, not chronic pain. Doses ranged widely, from 0.5 to 10 mg/kg, up to 400 mg a day.
Three studies compared oral ketamine against other analgesics and found no difference between groups. Two compared it against placebo with mixed results, and the positive one concerned intraoperative pain and local anesthetic use. Adverse reactions were common, and their severity often went unreported.
So the chronic-pain evidence inside that review is sparse and mixed. The authors called it preliminary, and suggested oral ketamine might be considered for selected people with refractory chronic neuropathic pain.
That's a long way from established. Oral ketamine studied for pain also isn't an at-home ketamine program marketed for depression.
What About Spravato for Chronic Pain?
Spravato is not FDA approved for chronic pain, and its evidence program is psychiatric. 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.
Direct chronic-pain evidence for it is very limited. Studies of esketamine in surgical or postoperative settings answer a different question and shouldn't be borrowed. Racemic ketamine, esketamine, and the branded nasal spray aren't interchangeable.
Why Might Ketamine Affect Chronic Pain?
In some chronic-pain conditions the nervous system becomes unusually responsive to pain signals. Repeated input can make spinal cord neurons fire more and more readily, which researchers call wind-up, and the broader pattern is central sensitization.
Ketamine blocks NMDA receptors, which are involved in that amplification. Blocking them may temporarily turn the volume down.
That's a plausible mechanism, not proof of clinical benefit. Plenty of drugs with sensible mechanisms don't end up helping patients.
What Are the Main Risks in Chronic Pain Treatment?
General side effects are covered in our guides on ketamine side effects and whether ketamine therapy is safe. What's different here is exposure.
Pain protocols can involve longer infusions, repeated courses, and higher cumulative doses than psychiatric treatment. The 2018 guideline noted that higher dosages and more frequent infusions carry greater risk, specifically flagging liver and bladder effects with repeated high exposure.
The 2025 Cochrane review found IV ketamine may increase adverse events, with a risk ratio around three, though certainty about harms stayed limited.
Common effects include dissociation, nausea, raised blood pressure, and sedation. For the longer view, see long-term effects and misuse risk.
Who Has Actually Been Studied?
Adults, mostly, with severe or refractory pain who had already tried standard treatments without enough relief. Samples have been small and populations carefully selected.
That limits what the results tell you. Someone with moderate chronic back pain isn't the person these trials enrolled.
This research is about chronic pain specifically. Acute and postoperative ketamine studies form a much larger literature answering a different question, and cancer pain and headache disorders were excluded from the Cochrane review entirely.
Is Ketamine FDA Approved for Chronic Pain?
No. Ketamine injection is FDA approved as an anesthetic. Current labeling doesn't list chronic pain, CRPS, neuropathic pain, or fibromyalgia. Spravato has no chronic-pain indication.
Using ketamine for pain is off-label, which is legal and routine in pain medicine. It doesn't mean improper or unsafe. It does mean no regulator has reviewed the evidence for this use, and anesthetic approval says nothing about whether ketamine treats chronic pain.
Where Does Ketamine Fit Into Chronic Pain Treatment?
In the studies, it has generally been used for refractory pain after more established options fell short. That's the population the evidence describes.
It hasn't been shown to be a first treatment for ordinary chronic pain, a substitute for diagnosis-specific care, a universal alternative to opioids, or a cure.
CRPS is where the evidence has most clearly supported considering it, and even there the limits are real.
What Should You Ask a Ketamine Provider About Pain Treatment?
These questions separate pain-experienced clinics from ones that mainly treat depression.
- What specific pain diagnosis are you treating?
- What evidence supports ketamine for that diagnosis?
- How much experience do you have with chronic pain rather than depression?
- What will you measure besides a pain score?
- How will we judge whether treatment is worth continuing?
- What evidence supports the infusion protocol you're recommending?
- How do you monitor longer or repeated infusions?
- What happens if relief lasts only hours or days?
- How does this fit with the rest of my pain treatment?
Finding a Provider for Ketamine Pain Treatment
Worth knowing before you start calling: many ketamine clinics treat depression and not pain. Those are different evaluations, different protocols, and often different specialties.
A clinic built for psychiatric infusions may not diagnose CRPS, may not employ a pain physician, and may not use pain-specific protocols at all. Being listed in a directory doesn't mean a clinic treats your condition.
Ask directly whether they treat your specific diagnosis before booking anything. Our guide on choosing a ketamine clinic covers what else to check, and you can search clinics near you or browse infusion clinics.