What does research actually tell us about IV ketamine and SGB? We selected six key studies and added more publications to explore, with straightforward explanations of the findings, who they apply to, and what remains uncertain.
What have studies found about IV ketamine for depression that has not improved with previous treatments? We also include findings on suicidal thoughts and post-traumatic stress, along with important limitations.
New England J Medicine
In a large study of depression that had not improved with previous treatments, 55.4% of patients receiving ketamine had a meaningful improvement, compared with 41.2% of those receiving electroconvulsive therapy (ECT). Ketamine was found to be no less effective than ECT in the group studied, which excluded depression with psychotic features.
Read the study ↗BMJ
In a study of 156 adults hospitalized with severe suicidal thoughts, 63% of people given ketamine reached remission of those thoughts after three days, compared with 31.6% in the control group. The difference was not statistically significant in the subgroup with depression alone, and the study did not show whether suicide attempts were prevented.
Read the study ↗Am J Psychiatry
Among the 39 people who completed the ketamine infusion series, 59% experienced a meaningful improvement in depression symptoms and 23% achieved remission. Participants who responded to treatment had an average 21.6-point reduction on a depression severity scale.
Read the study ↗Arch. Gen. Psychiatry
In this early, small study, 71% of patients receiving ketamine responded to treatment and 29% reached remission. The findings sparked considerable research interest, but the number of participants was limited.
Read the study ↗Am J Psychiatry
After treatment, 64% of patients receiving ketamine showed a meaningful improvement in depression, compared with 28% of those receiving a different medication for comparison. This controlled study provides useful evidence but does not predict an individual patient’s outcome.
Read the study ↗J Clin Psychiatry
In an analysis of routine clinical care, IV ketamine was associated with a faster and greater improvement in depression scores than esketamine delivered as a nasal spray. Because treatment was not assigned at random, the findings do not prove that one treatment is always better.
Read the study ↗EClinicalMedicine
Researchers compared results across different depression studies and found evidence of benefit from IV ketamine. The comparison with esketamine nasal spray was indirect: the two approaches were not tested head-to-head under the same conditions.
Read the study ↗Psychiatry Research
This study found that when depression and post-traumatic stress occur together, the risk of suicide attempts may be higher. Importantly, it examined risk factors and did not test whether ketamine treatment works.
Read the study ↗Preventive Medicine
Four of five studies of IV ketamine found a statistically significant short-term reduction in suicidal thoughts. This should not be interpreted as proof that ketamine reduces suicide attempts or deaths.
Read the study ↗Am J Psychiatry
In a small PTSD study, 67% of patients receiving ketamine showed a meaningful improvement in symptoms, compared with 20% in the control group. Depression scores also improved, but more research is needed before drawing broad conclusions.
Read the study ↗Neuropsychopharmacology
This study did not find a statistically significant improvement in PTSD symptoms compared with the control group, although depression symptoms improved. Including studies with less favorable results helps explain the limits of the evidence.
Read the study ↗Molecular Psychiatry
Using brain scans, researchers found a connection between changes in receptors involved in communication between brain cells and improvements in depression symptoms after ketamine. These findings help explore a possible mechanism, but do not predict what will happen for a particular patient.
Read the study ↗Nature
Researchers studied a substance produced when the body breaks down ketamine and found signs that it may contribute to antidepressant-like effects in mice. These are early animal findings, not proof of the same effect in people.
Read the study ↗Molecular Psychiatry
This review describes several possible pathways through which ketamine may affect communication between brain cells. Its mechanisms remain under investigation; the review itself did not measure treatment success rates in patients.
Read the study ↗What do we know about how stellate ganglion block may affect symptoms of post-traumatic stress and anxiety? Some studies compared the treatment with a control group, while others followed patients without a comparison group. This distinction matters when interpreting the results.
JAMA Psychiatry
In a controlled trial, participants were assigned to receive two SGB procedures or to a control group. After eight weeks, PTSD symptom scores improved by an average of 12.6 points with SGB, compared with 6.1 points in the control group. The study involved service members with mostly mild-to-moderate symptoms, and follow-up was short.
Read the study ↗Pain Physician
In a controlled study of anxiety that had not improved sufficiently with previous treatments, the average anxiety score improved by 9.6 points in the SGB group, versus 3.6 points in the control group. The trial took place at one center and followed patients for up to 12 weeks, so further research is needed.
Read the study ↗Pain Physician
PTSD symptom questionnaire scores decreased by an average of about 29 points after treatment, measured 7–30 days later. Because this was an observational study, it cannot establish how much of the change was caused by the treatment itself. The study used an older PTSD Checklist version based on DSM-IV.
Read the study ↗Translational Psychiatry
A further analysis of a controlled trial found greater improvement in symptoms such as hypervigilance, trouble concentrating and disturbed sleep. After eight weeks, 32.4% of the SGB group fell below the clinical threshold for the arousal-and-reactivity symptom cluster, compared with 10.8% in the control group. This does not mean full remission from PTSD.
Read the study ↗J Personalized Medicine
In a follow-up study of patients who received SGB, anxiety scale scores decreased by an average of 8.3 points, and 75.5% showed a clinically meaningful improvement. Without a control group, it is difficult to determine how much of the change resulted from treatment.
Read the study ↗Brain Sciences
A medical-records review found lower anxiety scores in 86.8% of patients. The average score fell from 15.52 to 7.28. As participants were not randomly assigned to treatment, this does not establish cause and effect.
Read the study ↗J Traumatic Stress
A small study combining SGB with trauma-focused psychotherapy found substantial reductions in symptoms. After one month, about half the participants no longer met PTSD diagnostic criteria. The study could not separate the contribution of the two treatments.
Read the study ↗Military Medicine
Researchers examined patients who had not responded sufficiently to a right-sided neck block. Some experienced benefits after an additional left-sided procedure. These observational findings cannot guarantee improvement for someone who did not respond initially.
Read the study ↗Military Medicine
In a retrospective study of 23 people with both PTSD symptoms and a history of traumatic brain injury, neurobehavioral symptoms improved after two-sided SGB. Because there was no control group, the study cannot establish whether SGB caused that change.
Read the study ↗Clin. Transl. Neuroscience
In a follow-up study, 96% of patients receiving SGB showed some reduction in their PTSD symptom scores over six months. Without a comparison group, we cannot determine how much of that improvement was caused by treatment.
Read the study ↗Psychother Psychosom
In this randomized study, 86 service members and veterans received SGB either before or after intensive trauma-focused cognitive processing therapy. PTSD symptoms improved in both groups, but improved faster when SGB was given first. Participants knew when they received SGB, and the study could not isolate the effect of SGB without psychotherapy.
Read the study ↗J Neurol Disord Stroke
This study compared SGB procedures performed at different levels of the neck. Both groups improved, but no statistically significant difference was established between the two approaches.
Read the study ↗Chronic Stress
Researchers brought together existing studies of SGB for conditions including PTSD and anxiety. The review helps explain the state of the evidence and its gaps; it is not a new treatment trial.
Read the study ↗Translational Psychiatry
In mice, researchers found clues that SGB may affect brain pathways involved in fear responses. This is a possible biological explanation, not direct evidence of effectiveness in people.
Read the study ↗Frontiers in Psychiatry
This review found preliminary evidence that sympathetic nerve blocks may be associated with improved symptoms. Most included studies were observational, highlighting the need for larger controlled trials before firm conclusions about effectiveness can be drawn.
Read the study ↗Percentage of patients with an improvement of at least 10 points on the PCL-5 PTSD symptom scale. These are internal clinical follow-up figures, not results from a controlled trial, and they do not predict individual outcomes.
This page summarizes published research and separate clinical follow-up data. It is for informational purposes and is not a substitute for an individualized medical assessment or advice.
Dr. Jason Cohen is a specialist in pain medicine and anesthesia, part of the global Stella organization that provides mental health care to tens of thousands of people across the United States, Australia, and Israel. Dr. Cohen is a leading expert in the dedicated SGB protocol for treating post-traumatic stress and anxiety disorders.
