Low Back Pain and Sciatica and Magnet Therapy

Long popular in Japan, magnet therapy has entered public awareness in the United States, stimulated by golfers and tennis players extolling the virtues of magnets in the treatment of sports-related injuries. Magnetic knee, shoulder, and ankle pads, as well as insoles and mattress pads, are widely available and are touted as providing myriad healing benefits.

A double-blind, placebo-controlled crossover trial of 54 people with knee or back pain compared a complex static magnet array against a sham magnet array.¹⁸ Participants used either the real or sham device for 24 hours; then, after a 7-day rest period, they used the opposite therapy for another 24 hours. Evaluations showed that use of the real magnet was associated with greater improvements than the sham treatment.

Benefits were also seen in a double-blind, placebo-controlled trial of 43 people with chronic knee pain who used fairly high-power but otherwise ordinary static magnets continuously for 2 weeks.¹⁹

And, in another placebo-controlled trial, the use of a magnetic knee wrap for 12 weeks was associated with a significant increase in quadriceps (thigh muscle) strength in patients with knee osteoarthritis.²⁰

A double-blind, placebo-controlled crossover study of 20 people who had chronic low back pain for at least 6 months' duration failed to find any evidence of benefit.²¹ However, the alternating pole magnet used in this study produced a very weak magnetic field.

Another study found hints of benefit that failed to reach statistical significance.²² In a double-blind study of 101 people with chronic neck and shoulder pain, use of a magnetic necklace failed to prove more effective than placebo treatment.²³ Another study failed to find magnetic insoles helpful for heel pain.²⁴

Safety Issues

In general, magnets appear to be safe; the biggest risk appears to be irritation from tape holding them in place. MRI machines, for example, expose the body to gigantic magnetic fields, and extensive investigation has found no evidence of harm. However, during the MRI, the patient is subjected to a high level of magnetism for a short period of time, whereas people who use static magnets daily or sleep on them every night are subjected to a low level of magnetism over a long period of time. So far, it is not known whether this type of exposure has any deleterious effects. Nonetheless, one study, in which participants slept on a magnetic mattress pad every night for 4 months, found no side effects. ¹ In addition, a safety study of rTMS found no evidence of harm. ² In a large study in which rTMS was administered to numerous depressed patients, totaling over 10,000 cumulative treatment sessions, no significant adverse effects were reported. Transient headache and scalp discomfort were the most frequent problems reported. There were no seizures, nor changes in hearing or cognition. ³ It was previously thought that people with implantable cardioverter defibrillators (ICDs) and pacemakers should not use magnetic devices at all, but this recommendation has been adjusted. One study found that with the exception of magnetic mattresses and mattress pads, most magnets sold for therapeutic purposes do not interfere with the magnetically activated switches present in most pacemakers. Magnetic mattress pads can deactivate and alter the function of ICDs and pacemakers, but other therapeutic magnets are safe if kept 6 inches or further from these devices. ⁴ There are theoretical concerns that magnets might be risky for people with epilepsy. Similarly, until the physiological effects of magnet treatments are better understood, pregnant women should avoid them.