Yes, ketamine is used for pain, and its role has expanded significantly over the past two decades. Originally developed as a surgical anesthetic in the 1960s, ketamine is now administered at much lower doses to treat several types of chronic and acute pain, particularly when standard treatments have failed. It works differently from opioids and other painkillers, which is precisely what makes it valuable for pain that doesn’t respond to conventional options.
How Ketamine Works on Pain
Most painkillers target one of a few well-known pathways in the nervous system. Ketamine takes a different route. It blocks a receptor in the brain and spinal cord involved in processing and amplifying pain signals. When pain becomes chronic, these receptors can get stuck in an overactive state, a process called central sensitization. Your nervous system essentially turns up the volume on pain, making normal sensations feel painful and painful sensations feel worse. Ketamine dials that volume back down.
Beyond blocking those receptors directly, ketamine also appears to reduce the release of glutamate, the brain’s primary excitatory chemical messenger. Excess glutamate can damage nerve cells over time, so by limiting its release, ketamine may have a protective effect on the nervous system. Researchers describe this as ketamine “resetting” overactive brain circuits, though achieving that reset seems to require a minimum dose or duration of treatment.
Chronic Pain Conditions It Treats
Ketamine is most commonly used for chronic pain conditions that haven’t responded well to other treatments. The strongest body of evidence exists for complex regional pain syndrome (CRPS), a condition that causes severe, burning pain usually in an arm or leg. In studies that tracked treatment response, roughly half of CRPS patients achieved meaningful long-term pain relief from ketamine infusions. One U.S. study found that a 10-day series of outpatient infusions provided pain relief superior to placebo for up to 12 weeks. A Dutch study using a 5-day continuous infusion in a hospital setting showed similar results, with relief lasting up to 11 weeks. In one retrospective review of 33 patients, 54% were completely pain-free for three months or longer.
These numbers vary considerably from study to study. Some trials have reported response rates as high as 65%, while others found only 20% of patients experienced meaningful relief at three months. The variation likely reflects differences in dosing, infusion length, and how “response” was defined. Still, for a condition as difficult to treat as CRPS, these results are notable.
Ketamine is also used for other chronic pain conditions including fibromyalgia, neuropathic pain from nerve damage, and certain headache disorders. For diabetic nerve pain specifically, the evidence is more limited. Topical ketamine creams, sometimes combined with other medications, have shown mixed-to-modest benefits in small studies, though they do avoid the side effects that come with oral or intravenous medications. Current guidance reserves ketamine for diabetic nerve pain only in cases where standard treatments have failed.
Ketamine After Surgery
One of ketamine’s most practical applications is reducing the need for opioids after surgery. A meta-analysis of 11 studies looking at patients who had open abdominal surgery found that adding a ketamine infusion to the recovery plan meaningfully decreased opioid use in the first 24 hours. The researchers considered a 20% reduction in opioid consumption clinically significant, and the pooled data showed ketamine consistently cleared that threshold.
This matters because post-surgical opioid use carries real risks: nausea, constipation, slowed breathing, and the potential for longer-term dependence. By cutting opioid needs during that critical early recovery window, ketamine can make the post-operative experience smoother while reducing exposure to drugs that carry their own serious downsides.
How It’s Administered
For pain management, ketamine is given at doses far below what’s used for anesthesia. These are called subanesthetic doses. The most common method is an intravenous infusion, where the drug is delivered slowly through an IV over a set period of time.
Dosing depends on the situation. For patients who haven’t been taking opioids regularly, infusion rates typically range from 0.05 to 0.4 mg per kilogram of body weight per hour. Patients who are opioid-tolerant, meaning their bodies have adapted to regular opioid use, often need higher rates of up to 1 mg per kilogram per hour. For chronic pain specifically, higher cumulative doses and repeated infusion sessions are common because the goal is to reverse that central sensitization process rather than simply block pain in the moment.
Infusions for chronic pain can be given as outpatient sessions lasting a few hours or, in some protocols, as continuous multi-day infusions in a hospital. The choice depends on the condition being treated, its severity, and the clinical setting.
How Long Relief Lasts
This is the key practical question, and the answer is somewhat sobering. Short infusions lasting a few hours tend to provide pain relief only during the infusion itself, with little carry-over effect. Longer infusions lasting 4 to 14 days tell a different story: they can produce pain relief lasting up to three months after treatment ends.
However, the effect fades. A meta-analysis found that during the first week after treatment, the pain-relieving effect was large and robust. By week four, it had dropped to a moderate level, still statistically meaningful but clearly declining. This pattern suggests that most patients will need retreatment within four to six weeks after their initial course. For many people, ketamine for chronic pain becomes a recurring treatment rather than a one-time fix.
Side Effects and Risks
At the subanesthetic doses used for pain, ketamine’s most common side effects are short-lived and occur during or shortly after infusion. These include distortions of time and space, a floating or detached feeling, nausea, and dizziness. At higher doses, even below the anesthetic threshold, some patients experience vivid hallucinations or a dreamlike altered state of consciousness.
The more serious risks are associated with repeated or prolonged use. Bladder damage is the best-documented long-term concern. First reported in 2007 among people using ketamine recreationally on a daily basis, ketamine-associated bladder inflammation causes increased urgency, frequent urination, painful urination, and blood in the urine. Over time, it can progress to bladder wall scarring, narrowing of the tubes connecting the kidneys to the bladder, and in severe cases, chronic kidney failure. While these extreme outcomes are primarily seen with heavy recreational use, the risk is relevant for anyone receiving repeated medical infusions over months or years.
Ketamine also raises blood pressure and heart rate temporarily, which makes it a concern for people with uncontrolled cardiovascular disease. It is generally not recommended for people with a history of psychotic disorders, active substance use disorders, cognitive decline, or those who are pregnant or breastfeeding. In 2018, a joint consensus from the American Society of Regional Anesthesia and Pain Medicine, the American Academy of Pain Medicine, and the American Society of Anesthesiologists formalized guidelines for safe use, recommending that infusions be administered in monitored clinical settings with appropriate screening beforehand.
Where Ketamine Fits in Pain Treatment
Ketamine is not a first-line painkiller. It occupies a specific niche: pain that has resisted other treatments, particularly neuropathic and centralized pain conditions where the nervous system itself has become part of the problem. Its unique mechanism makes it effective where opioids, anti-inflammatory drugs, and nerve-targeting medications have fallen short.
For post-surgical pain, its role is more supplementary. It works alongside other medications to reduce opioid consumption and improve recovery. In both contexts, ketamine is administered under medical supervision, with dosing carefully tailored to the individual. The temporary nature of its relief, the need for repeated treatments, and the potential for side effects mean it works best as one component of a broader pain management plan rather than a standalone solution.