People take ketamine for two broad reasons: as a medical treatment for depression and chronic pain, or recreationally for its dissociative and hallucinatory effects. On the medical side, ketamine has become one of the most significant developments in psychiatric treatment in decades, particularly for people whose depression hasn’t responded to standard antidepressants. On the recreational side, it produces feelings of detachment, visual hallucinations, and altered perception that some users seek out in social or exploratory settings.
Treatment-Resistant Depression
The most common medical reason people take ketamine is severe depression that hasn’t improved with traditional antidepressants. Roughly 30% of people with major depression don’t respond adequately to standard medications like SSRIs, and ketamine offers a fundamentally different approach. Instead of gradually adjusting serotonin levels over weeks, ketamine works on a different brain signaling system, one involving a chemical messenger called glutamate, and it acts fast.
How fast? People can begin feeling relief within about 40 minutes of a ketamine infusion, according to Harvard Health Publishing. That speed is remarkable compared to conventional antidepressants, which typically take four to six weeks to show meaningful effects. For someone in a deep depressive episode, especially with suicidal thoughts, those weeks of waiting can feel unbearable.
That said, ketamine isn’t a cure-all. About 50% of people with treatment-resistant depression don’t respond to ketamine or its derivative esketamine. The effects also tend to be temporary, wearing off within days to weeks, which means most treatment plans involve repeated sessions rather than a single dose.
The FDA-Approved Version
In 2019, the FDA approved a nasal spray called Spravato (esketamine), a close chemical relative of ketamine, for two specific uses: treatment-resistant depression in adults and depressive symptoms in adults with major depression who have active suicidal thoughts or behavior. It’s the only ketamine-related product with formal FDA approval for psychiatric use.
Spravato isn’t something you pick up at a pharmacy and take at home. It’s available only through a restricted program, and every dose must be administered under direct supervision of a healthcare provider. After each session, you’re monitored for at least two hours because of the risk of sedation, dissociation, and changes in blood pressure and breathing. You also can’t drive until the next day after a full night’s sleep. These safeguards exist because ketamine is a powerful drug with real short-term effects on consciousness and coordination.
Outside of Spravato, many clinics offer “off-label” intravenous ketamine infusions for depression. These aren’t FDA-approved for psychiatric use but are legal because ketamine itself has been an approved anesthetic since the 1970s. The quality, protocols, and oversight at these clinics vary widely.
Chronic Pain Conditions
Ketamine is also used for chronic pain that hasn’t responded to other treatments. Two conditions where it shows up most often are complex regional pain syndrome (CRPS), a condition causing severe burning pain usually in a limb, and fibromyalgia, which involves widespread pain and tenderness throughout the body. Both are notoriously difficult to manage with conventional painkillers.
A typical protocol involves low-dose intravenous infusions given over 40 minutes for five consecutive days. Ketamine works differently from opioids. Rather than simply blocking pain signals, it interrupts a process called central sensitization, where the nervous system essentially gets stuck in a heightened pain state. By resetting some of that overactive signaling, ketamine can reduce pain intensity for weeks or months after a treatment course, though the duration of relief varies significantly from person to person.
PTSD Treatment
The picture for PTSD is more complicated than many people realize. A 2022 meta-analysis published in Frontiers in Psychiatry found that ketamine’s effectiveness depends heavily on whether the PTSD is recent or long-standing. For chronic PTSD, ketamine significantly reduced symptoms across 91 patients in three trials, and it did so without triggering psychosis or mania. But for early-stage PTSD, the results were concerning: in 65 patients across three separate trials, ketamine not only failed to help but actually made symptoms worse.
This distinction matters. Ketamine isn’t a blanket treatment for trauma. Its usefulness appears tied to how long the condition has been present, suggesting it may work better on the entrenched neural patterns of long-standing PTSD than on the acute stress responses of recent trauma.
How It Compares to Other Treatments
For severe depression, electroconvulsive therapy (ECT) has long been considered the gold standard when medications fail. A 2024 meta-analysis comparing ketamine to ECT across six trials and 655 patients found that ECT still produces greater reductions in depression scores overall, and among hospitalized patients, ECT was clearly superior in response rate. However, ketamine and ECT produced comparable remission and relapse rates in the broader population, and ketamine works faster. A 2025 meta-analysis confirmed that ketamine shows a quicker onset of antidepressant effects even when both treatments reach similar outcomes by the end of a treatment course.
For many patients, ketamine’s appeal over ECT comes down to practical factors: it doesn’t require general anesthesia, it doesn’t cause the memory problems ECT is known for, and infusion sessions are shorter and less physically demanding. But for the most severe cases, particularly people who are hospitalized, ECT remains the stronger option based on current evidence.
Recreational Use
Outside of medical settings, ketamine is used recreationally for its dissociative and hallucinatory properties. At low doses, it distorts the perception of time and space, producing mild hallucinations and a dreamy sense of detachment. A study of recreational users found that two-thirds reported the most appealing effects were “melting into the surrounding,” visual hallucinations, out-of-body experiences, and giggliness.
At higher doses (roughly 150 mg or more), the experience intensifies dramatically into what users call a “K-hole,” a state of profound dissociation where a person feels deeply detached from their body and surroundings. Reality seems to recede into the distance while perception feels buried deep within consciousness. Some users describe this as mystical or transformative. Others find it terrifying. The line between the two can be unpredictable.
Ketamine’s recreational popularity has grown in club and festival settings partly because its effects are relatively short-lived compared to other psychedelics, typically lasting 45 minutes to an hour when snorted, and because it produces a different quality of altered state than drugs like LSD or psilocybin.
Physical Risks of Regular Use
Supervised medical use of ketamine at controlled doses carries manageable short-term side effects: nausea, dizziness, dissociation, and temporary increases in blood pressure. These resolve within hours. The more serious risks emerge with frequent, unsupervised use.
The most damaging long-term consequence is severe bladder injury. Chronic ketamine use causes ulcerative cystitis, a painful inflammation and ulceration of the bladder lining. Symptoms include blood in the urine, extreme urinary urgency and frequency, bladder pain, and dramatically reduced bladder capacity. In heavy users, the damage can extend to the kidneys, with reflux of urine back toward the kidneys impairing their function. This bladder damage has been called irreversible in some cases, and it can develop in users as young as their twenties.
Psychological dependence is another concern with regular use. While ketamine doesn’t produce the same physical withdrawal syndrome as opioids or alcohol, people can develop a compulsive pattern of use, particularly if they’re chasing the dissociative state as an escape from emotional distress. This creates an uncomfortable overlap with the very conditions ketamine is being used to treat medically, making the line between therapeutic and problematic use one that requires careful clinical oversight.