Candidates for ketamine treatment are typically people with treatment-resistant depression, meaning they’ve tried at least two antidepressant medications without adequate improvement. But depression isn’t the only qualifying condition. Ketamine is also used for certain chronic pain syndromes, PTSD, OCD, and increasingly for acute suicidal ideation, with specific medical and psychiatric criteria determining whether someone is a good fit.
Treatment-Resistant Depression: The Primary Indication
The most well-established use of ketamine is for treatment-resistant depression (TRD). You generally qualify if you’ve tried at least two first-line antidepressants, each at an adequate dose for six to eight weeks, without meaningful symptom relief. First-line medications include SSRIs, SNRIs, bupropion, and mirtazapine. If two or more of these haven’t worked for you, most clinicians would consider your depression treatment-resistant.
The response rates for this group are notable. A single intravenous ketamine infusion produces a meaningful response in roughly 50 to 70 percent of patients with treatment-resistant depression, with many people noticing improvement within hours rather than the weeks that conventional antidepressants require. In a controlled trial comparing ketamine to a placebo sedative, 65 percent of ketamine patients responded compared to 28 percent in the control group. Response here means at least a 50 percent reduction in depression severity scores.
There is also an FDA-approved nasal spray form called esketamine (Spravato), which is specifically approved for two groups: adults with treatment-resistant depression, and adults with major depressive disorder who have acute suicidal ideation or behavior. The nasal spray must be taken in combination with an oral antidepressant and administered in a certified clinic. IV ketamine, by contrast, is used off-label for depression and other conditions, though it has been safely used in clinical practice for over a decade.
Other Psychiatric Conditions
Beyond depression, ketamine has shown significant benefit for PTSD, OCD, and alcohol use disorder, though these uses are considered off-label. A meta-analysis published in CNS Spectrums found statistically significant symptom improvement across all three conditions. For PTSD, both standard and treatment-resistant cases responded well. For OCD, patients showed meaningful reductions on the standard severity scale. People with alcohol use disorder reported decreased urge to drink, higher rates of abstinence, and longer time to relapse.
Bipolar depression is a more nuanced case. Ketamine does appear to help with depressive episodes in bipolar disorder, and the risk of triggering a manic or hypomanic episode appears to be minimal based on current evidence. However, clinicians typically take extra precautions with bipolar patients, and this remains an area where treatment decisions are highly individualized.
Chronic Pain Candidates
Ketamine was originally developed as an anesthetic, and its pain-relieving properties make it a candidate for several chronic pain conditions. Complex regional pain syndrome (CRPS) is one of the most studied, with multiple clinical trials using ketamine infusions for patients who haven’t responded to other treatments. Neuropathic pain, sickle cell disease, and acute exacerbations of conditions like Ehlers-Danlos syndrome have also been treated with ketamine, though the evidence base for these is smaller and often limited to case reports.
Patients who are opioid-dependent or opioid-tolerant represent a particularly relevant group. Because ketamine works through a completely different mechanism than opioids, it can provide pain relief for people whose bodies have built up tolerance to standard pain medications. Consensus guidelines from the American Society of Regional Anesthesia and Pain Medicine specifically note that opioid-dependent patients may benefit from ketamine during acute flare-ups of chronic pain.
Who Should Not Receive Ketamine
Several medical conditions rule out ketamine treatment. The American Psychiatric Nurses Association lists the following exclusion criteria:
- Active substance abuse of alcohol, cannabis, non-prescribed medications, or other drugs
- History of psychosis, including schizophrenia or other psychotic disorders
- Uncontrolled high blood pressure, since ketamine temporarily raises blood pressure and heart rate
- Unstable cardiovascular disease, including high-risk coronary artery disease
- Increased intracranial pressure
- Current pregnancy
- Previous negative response to ketamine
Severe liver dysfunction is another important disqualifier. Ketamine is processed by the liver, and repeated infusions have been linked to elevated liver enzymes in some studies. One trial involving CRPS patients had to be terminated after a second round of moderate-dose infusions caused significant liver function problems. Serious kidney disease is also a concern for the same reason: impaired clearance means the drug stays in the body longer and side effects become more likely.
Substance Use History: A Gray Area
Active substance abuse is a clear exclusion, but a past history of substance use doesn’t automatically disqualify you. Clinical trials for ketamine and alcohol use disorder, for example, have enrolled participants with active moderate-to-severe alcohol problems, though they required at least 24 hours of abstinence before treatment and negative drug screens. The key distinction most clinics draw is between current, uncontrolled substance use and a managed or remote history. If you have a substance use history, expect your provider to evaluate it carefully on a case-by-case basis.
Age Considerations
Most ketamine clinics treat adults 18 and older. There is no hard upper age limit, but older adults require special consideration. As people age, the liver metabolizes ketamine more slowly, which means the drug stays active in the body longer and the risk of side effects increases. Elderly patients are also more sensitive to ketamine’s dissociative effects (hallucinations, confusion, emotional detachment), which can be particularly disruptive for those with pre-existing cognitive decline.
For patients over 65, clinicians typically use lower doses, often in the range of 0.15 to 0.5 mg/kg intravenously. Studies have included participants up to 85 years old, so advanced age alone isn’t a barrier, but it does change the risk-benefit calculation and the dosing approach.
What the Screening Process Looks Like
Before your first treatment, expect a thorough intake process. According to guidelines from the American Association of Nurse Anesthesiology, a standard screening includes a consultation with a psychiatric provider who has experience with ketamine, a full medical history and physical exam, and medical clearance from your primary care provider. Depending on your health history, you may also need specialty clearance from a cardiologist or neurologist.
Lab work is part of the process. Liver function tests and kidney function markers (creatinine) are commonly ordered before treatment begins, both to check for contraindications and to establish a baseline for monitoring. If you’re being treated for depression, your provider will also verify that you meet the criteria for treatment resistance, meaning documented trials of at least two antidepressants that didn’t work.
Patients in good overall physical health (classified as physical status 1 or 2 on the standard anesthesia scale) are the most straightforward candidates. Those with more significant medical conditions can still be considered but require additional precautions and closer monitoring during infusions.
What to Realistically Expect
If you qualify, it helps to know what the evidence actually shows. The rapid response is real: most studies report peak benefit within 72 hours of a single infusion, with some patients feeling improvement within hours. But this effect fades. Without repeated treatments, the antidepressant benefit of a single infusion typically wears off within one to two weeks. Most treatment protocols involve a series of infusions over several weeks, sometimes followed by maintenance sessions.
Not everyone responds. While 50 to 70 percent is a strong response rate, especially for a population that has already failed multiple medications, it means roughly one in three patients won’t experience significant improvement. The intranasal form has shown somewhat lower response rates in some studies, around 44 percent, though it offers a more accessible delivery method for ongoing treatment.