Intravenous Magnesium May Improve Postoperative Pain and Complex Regional Pain Syndrome

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Magnesium’s potential action as a voltage-gated antagonist of N-methyl-D-aspartate receptors to mediate pain transduction is reviewed here.

The use of magnesium has been approved by the Food and Drug Administration in the United States for the treatment of hypomagnesemia, seizure prevention in eclampsia or preeclampsia, arrhythmia, and constipation. Its potential action as a voltage-gated antagonist of N-methyl-D-aspartate (NMDA) receptors to mediate pain transduction was reviewed in an article published in Anesthesiology and Pain Medicine.

Researchers determined that magnesium administered intravenously can act immediately as a pain reliever, with relief lasting for 30 minutes. It disrupts the central nervous system membrane voltage-gated ion channels by preventing calcium from entering cells, thereby blocking the release of glutamate and neuropeptides and the potentiation of pain.

In a meta-analysis of magnesium for pain associated with abdominal surgery, the investigators found an association with reduced pain scores and less consumption of opioids. This trend was confirmed by multiple studies that observed significantly lower pain during the first 12 hours after surgery. By 24 hours, reduction of pain by magnesium was no longer significant, indicating it has a short-term effect.

A small pilot trial of magnesium treatment among patients with complex regional pain syndrome found that impairment and quality of life was improved at 12 weeks after 5 days of 70 mg/kg magnesium sulfate infusions with little risk for side effects.

Patients with chronic lower back pain with a neuropathic component reported relief at 6 months following 2 weeks of daily infusions followed by 400 mg oral magnesium oxide and 100 mg oral magnesium gluconate twice daily for 4 weeks.

The application for use of intravenous magnesium for other chronic pain ailments remains controversial.

Some evidence has indicated that patients with headache have low serum magnesium levels. According to observations, headaches have been eliminated in 80% of patients within 15 minutes of a magnesium infusion. Despite this observation, at clinical trial only 41% of patients reported clinically meaningful pain relief, and another study observed more successful headache relief in placebo recipients than those in the magnesium treatment group.

Similarly, conflicting studies for the application of intravenous magnesium for the treatment of migraine have been published. Overall, it remains unclear whether any clinical benefit may be achieved by administering magnesium for migraine relief.

For the treatment of peripheral neuropathy, 2 retrospective studies indicated there may be some benefit. However, more recently published studies did not confirm these findings among patients with colorectal cancer or refractory postherpetic neuralgia.

Overall, this review suggested intravenous magnesium may have some clinical applications for reducing chronic pain conditions or following surgical procedures; however, larger, longer duration trials are needed to determine exactly which patient population may find pain relief with intravenous magnesium therapy.


Urits I, Jung JW, Amgalan A, et al. Utilization of magnesium for the treatment of chronic pain. Anesthesiol Pain Med. 2021;11(1):e112348. doi:10.5812/aapm.112348