Magnetism can refer to the alteration of gravitational pull to the North Pole as well as to the invisible attraction two people feel toward one another. Both definitions, however, indicate a hidden but palpable force that pulls one object to another.
Historically, magnetism was discussed as early as 625 bc. in the writings of Aristotle.1 Later, mariners learned that magnetic rocks known as lodestones acted dependably as compasses when suspended from a string. With unfailing accuracy, the stone would come to rest in a north-south line, thus indicating the direction of the ship.2
All magnets have positively and negatively charged poles. Magnets bond when opposing poles are placed next to each other and repel when like poles face each other.
The medical uses of magnets are still being explored. More than $1 billion worth of OTC therapeutic magnets have been sold worldwide to date.3
The gauss (G) is the unit of measurement of a magnetic field. The earth’s magnetic field on its surface is approximately 0.5 G. Commercially available magnets usually claim strengths of anywhere from 300 G to 5,000 G; an electromagnet used in an MRI machine is 15,000 G or higher.
Basic research shows that when a magnet is placed on the skin, capillary walls relax, allowing for increased blood flow and oxygenation and removal of accumulated pain-producing prostaglandins. Theoretically, these actions relieve muscle spasms and, subsequently, pain.4
Since pain transmission requires the electrical activity found in nerve and muscle cells, properly aligned magnets could either block that action or, in cases of injury, promote healing.5 Magnets can be used in a constant, uninterrupted application (static therapy) or with manipulation of the magnetic field (pulsed therapy).
A meta-analysis of published clinical trials testing the efficacy of magnet therapy for pain showed no clear, statistically significant differences.6 Of the 29 studies examined, nine were randomized, placebo-controlled trials that explored the use of magnets for musculoskeletal pain. Four of these trials demonstrated a measurable reduction in pain but were not consistent in the strength of magnet used, length of use, and positioning of the magnets.
Of the four studies showing positive results, one was a small trial examining the effect of magnet therapy on fibromyalgia pain.7 This trial utilized a magnetic mattress pad of 1,100 G. Participants were randomized either to a placebo pad or the magnetic pad, and slept on the same pad for 16 weeks.
The patients were assessed for pain, fatigue, myalgia, physical function and sleep quality using the Fibromyalgia Impact Questionnaire. The magnetic pad group had statistically significant improvement in all areas compared with little or no change in the placebo group.
A small clinical trial used pulsed electromagnetic therapy (PEMT) to treat chronic low back pain.8 A total of 36 patients were randomized to PEMT or placebo treatment performed three times a week for three weeks. Patients were then followed for four weeks and asked to rate their pain on a numerical scale. Individuals in the treatment group reported a statistically significant decrease in pain for the entire month.
Another unique trial evaluated the efficacy of magnet therapy for menstrual pelvic pain.9 A device in the underwear secured the magnets to assure contact with the pelvis.
In this trial, 35 women with documented dysmenorrhea were randomized to wear either a strong magnet garment or a weaker magnetic placebo device for the two days prior to menses until the end of their cycle. Blinded results assessed by the McGill Pain Questionnaire showed a statistically significant reduction in pain in the group wearing the strong-magnet garment.
Redness of the skin in contact with the magnet has been reported, but most cases self-resolve within 24 hours of removal of the device. Patients who use cardiac pacemakers, implanted automatic defibrillators, or insulin pumps should not use magnet therapy without consulting their health-care provider.
Some manufacturers warn that magnets can interfere with the pharmacokinetics of transdermal medications, such as pain patches. Although this theory has not been proven, it warrants consideration.
COST, HOW SUPPLIED
The cost of magnet therapy is highly variable. Generally, the cost of the device rises with the quality and strength and varies from as low as $10 to as much as $100 or more. Patients should thoroughly research any product before buying.
Magnet therapy is still on the outer fringe of any sort of evidence-based practice. However, even the studies that did not show benefit failed to show any negative safety issues. Consequently, health-care professionals should be aware of the emerging data and help their patients make informed decisions regarding magnet therapy.
- Basford JR. A historical perspective of the popular use of electric and magnetic therapy. Arch Phys Med Rehabil. 2001;82:1261-1269.
- Boyer TH. The force on a magnetic dipole. Am J Physics. 1988;56:688-692.
- Kuipers NT, Sauder CL, Ray CA. Influence of static magnetic fields on pain perception and sympathetic nerve activity in humans. J Appl Physiol (1985). 2007;102:1410-1415. Available at jap.physiology.org/content/102/4/1410.long.
- Mayrovitz HN, Groseclose EE. Effects of a static magnetic field of either polarity on skin microcirculation. Microvasc Res. 2005;69:24-27.
- McLean M, Engstrom S, Holcomb R. Static magnetic fields for the treatment of pain. Epilepsy & Behavior. 2001;2:S74-S80.
- Pittler MH, Brown EM, Ernst E. Static magnets for reducing pain: systematic review and meta-analysis of randomized trials. CMAJ. 2007;177:736-742. Available at www.cmaj.ca/content/177/7/736.long.
- Colbert AP, Markov MS, Banerji M, Pill AA. Magnetic mattress pad use in patients with fibromyalgia: a randomized double-blind pilot study. J Back Musculoskeletal Rehab. 1999;13: 19-31.
- Lee PB, Kim YC, Lim YJ, et al. Efficacy of pulsed electromagnetic therapy for chronic lower back pain: a randomized, double-blind, placebo-controlled study. J Int Med Res. 2006;34:160-167. Available at imr.sagepub.com/content/34/2/160.long.
- Eccles NK. A randomized, double-blinded, placebo- controlled pilot study to investigate the effectiveness of a static magnet to relieve dysmenorrhea. J Altern Complement Med. 2005;11:681-687.
All electronic documents accessed January 15, 2014.