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Doctor, I have neuropathic pain. Will ketamine infusions relieve my pain?

Ketamine infusions with or without magnesium were not better than placebo at reducing chronic neuropathic pain.

What is the evidence?


  • There was no difference in the average daily pain intensity scores over 35 days between (1) people who received ketamine, (2) people who received ketamine plus magnesium, and (3) people who received a placebo

What kind of study was this?

This was a randomized controlled trial with a crossover design (all participants received all of the treatments but in a different order).

Who? This study included 20 people with chronic neuropathic pain (due to surgery 45%, radiculopathy 35%, trauma 10%, diabetes 1%, chemotherapy 1%) not improved with other treatments who had not received ketamine in the past (average age 55, 50% women).  

What? The study compared ketamine with or without magnesium infusions with placebo

Ketamine with or without Magnesium



Ketamine (0.5 mg/kg) given by infusion into a vein (IV)

Ketamine plus Magnesium given by infusion into a vein (IV) once every 35 days

Participants recorded their pain score daily after each infusion.

Placebo: A needle containing an inactive substance that has no effect on the outcome. Sometimes, it is referred to as a "sugar pill."

Participants recorded their pain score daily after each infusion.

Why was this research done?

Neuropathic pain is sometimes described as shooting pain or burning pain or a sensation of electrical shock. It is caused by injury or dysfunction of nerves within the central nervous system (brain or spinal cord) or peripheral nervous system (nerves outside of the brain or spinal cord). Ketamine and magnesium are agents that bind to pain receptors causing relief in some chronic pain conditions. Researchers wanted to know if ketamine infusions with or without magnesium would reduce neuropathic pain. The results show that ketamine with or without magnesium did not reduce pain more than placebo. It is possible that the doses of ketamine and magnesium used in the study were too low, the study was too small to detect a difference or the placebo effect was too strong.

This Evidence Summary is based on the following article:

Pickering G, Pereira B, Morel V, et al. Ketamine and Magnesium for Refractory Neuropathic Pain. Anesthesiology. 2020 Jul 1;133(1):154-164. doi: 10.1097/ALN.0000000000003345. PubMed

Published: Wednesday, May 19, 2021
Last Updated: Tuesday, July 13, 2021

Please note that the information contained herein is not to be interpreted as an alternative to medical advice from a professional healthcare provider. If you have any questions about any medical matter, you should consult your professional healthcare providers, and should never delay seeking medical advice, disregard medical advice or discontinue medication based on information provided here.