What is magnet therapy?

Overview

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, and insoles and mattress pads, are widely available and are thought to provide myriad healing benefits.

Despite this enthusiasm, there is little scientific evidence to support the use of magnets for any medical condition. However, some small studies suggest that various forms of magnet therapy might have a therapeutic effect in certain conditions.

History of magnet therapy. Magnet therapy has a long history in
traditional folk
medicine. Reliable documentation indicates that Chinese
doctors have believed in the therapeutic value of magnets for two thousand years
or more. In sixteenth-century Europe, Paracelsus used magnets to treat a variety
of ailments. Two centuries later, Franz Mesmer became famous for treating various
disorders with magnets.

In the middle decades of the twentieth century, scientists in various parts of
the world began performing studies on the therapeutic use of magnets. From the
1940s on, magnets became increasingly popular in Japan. Yoshio Manaka, one of the
influential Japanese acupuncturists of the twentieth century, used magnets in
conjunction with acupuncture. Magnet therapy also became a commonly used
technique of self-administered medicine in Japan. For example, a type of plaster
containing a small magnet became popular for treating aches and pains, especially
among the elderly. Magnetic mattress pads, bracelets, and necklaces also became
popular, mainly among the elderly. During the 1970s, both magnets and
electromagnetic machines became popular among athletes in many countries for
treating sports-related injuries.

These developments led to a rapidly growing industry creating magnetic products for a variety of conditions. However, the development of this industry preceded any reliable scientific evidence that static magnets actually work for the purposes intended. In the United States, it was only in 1997 that properly designed clinical trials of magnets began to be reported. Subsequently, results of several preliminary studies suggested that both static magnets and electromagnetic therapy may indeed offer therapeutic benefits for several disorders. These findings have escalated research interest in magnet therapy.

Types of magnet therapy and their uses. The term “magnet therapy” usually refers to the use of static magnets placed directly on the body, generally over regions of pain. Static magnets are either attached to the body by tape or encapsulated in specially designed products such as belts, wraps, or mattress pads. Static magnets are also sometimes known as permanent magnets.

Static magnets come in various strengths. The units of measuring magnet strength are gauss (G) and tesla (T); 1 tesla equals 10,000 G. A refrigerator magnet, for example, is around 200 G. Therapeutic magnets measure anywhere from 200 to 10,000 G, but the most commonly used measure from 400 to 800 G.

Therapeutic magnets come in two different types of polarity arrangements: unipolar magnets and alternating-pole devices. Magnets that have north on one side and south on the other are known, rather confusingly, as unipolar magnets. Bipolar or alternating-pole magnets are made from a sheet of magnetic material with north and south magnets arranged in an alternating pattern, so that both north and south face the skin. This type of magnet exerts a weaker magnetic field because the alternating magnets tend to oppose each other. Each type of magnet has its own recommended uses and enthusiasts. (There are many heated opinions, with no supporting evidence, on this matter.)

More complex magnetic devices have also been studied, not for home use, but for
use in physicians’ offices and hospitals. A special form of electromagnetic
therapy, repetitive transcranial magnetic stimulation (rTMS), is undergoing
particularly close study. rTMS is designed specifically to treat the brain with
low-frequency magnetic pulses. A large body of small studies suggest that rTMS
might be beneficial for depression. It is also being studied for the treatment of
amyotrophic lateral sclerosis (ALS), Parkinson’s disease, epilepsy, schizophrenia,
and obsessive-compulsive disorder.

Scientific Evidence

Static magnets. In double-blind, placebo-controlled trials, static magnets have shown promise for a number of conditions, but in no case is the evidence strong enough to be relied upon. In a 2007 review of all studies of static magnets as a treatment for pain, researchers concluded that there is no meaningful evidence that they are effective; they further concluded that current evidence suggests that, for some pain-related conditions, static magnets are not effective (a much stronger statement than the first).

Some magnet proponents claim that it is impossible to carry out a truly double-blinded study on magnets because participants can simply use a metal pin or a similar object to discover whether they have a real magnet or not. Some researchers have gotten around this by using a weak magnet as the placebo treatment. Other researchers have designed more complicated placebo devices that participants have been found unable to identify as fake treatments.

Rheumatoid arthritis. A double-blind, controlled trial of
sixty-four people with rheumatoid arthritis of the knee
compared the effects of strong alternating polarity magnets with the effects of a
deliberately weak unipolar magnet. Researchers used the weakened magnet as a
control group so that participants would not find it easy to break the blind by
testing the magnetism of their treatment.

After one week of therapy, 68 percent of the participants using the strong magnets (the treatment group) reported relief, compared with 27 percent in the control group. This difference was statistically significant. Two of four other subjective measurements of disease severity also showed statistically significant improvements. However, no significant improvements were seen in objective evaluations of the condition, such as blood tests for inflammation severity or physician’s assessment of joint tenderness, swelling, or range of motion. This study suggests that magnet therapy may reduce the pain of rheumatoid arthritis without altering actual inflammation. However, the mixture of statistically significant and insignificant results indicates that a larger trial is necessary to factor out “statistical noise.”

Post-polio syndrome. A double-blind, placebo-controlled study of fifty people with post-polio syndrome found evidence that magnets are effective for relieving pain. The magnets or placebo magnets were placed on previously determined trigger points (one per person) for forty-five minutes. (Trigger points are sore areas within muscle that, when pressed, cause relief in other areas of the muscle and conversely, when inflamed, cause pain in other parts of the muscle.) In the treatment group, 76 percent of the participants reported improvement, compared with 19 percent in the placebo group.

Fibromyalgia. A six-month, double-blind, placebo-controlled trial
of 119 people with fibromyalgia compared two commercially
available magnetic mattress pads with sham treatment and no treatment. Group 1
used a mattress pad designed to create a uniform magnetic field of negative
polarity. Group 2 used a mattress pad that varied in polarity. In both groups,
manufacturer’s instructions were followed. Groups 3 and 4 used sham treatments
designed to match in appearance the magnets used in groups 1 and 2. Group 5
received no treatment.

On average, participants in all groups showed improvement in the six months of the study. Participants in the treatment groups, especially group 1, showed a trend toward greater improvement; however, the differences between real treatment and sham or no treatment failed to reach statistical significance in most measures. This outcome suggests that magnetic mattress pads might be helpful for fibromyalgia, but a larger study would be necessary to identify benefits.

An earlier double-blind, placebo-controlled study of thirty women with fibromyalgia did find significant improvement with magnets compared with placebo. The women slept on magnetic mattress pads (or sham pads for the control group) every night for four months. Of the twenty-five women who completed the trial, participants sleeping on the experimental mattress pads experienced a significant decrease in pain and fatigue compared with the placebo group, along with significant improvement in sleep and physical functioning.

A single-blind study of somewhat convoluted design provides weak evidence that a gown made from a special “electromagnetic shielding fabric” can reduce fibromyalgia symptoms. The rationale for using this fabric is, however, somewhat scientifically implausible.

Peripheral neuropathy. A four-month, double-blind, placebo-controlled, crossover study of nineteen people with peripheral neuropathy found a significant reduction in symptoms compared with placebo. Participants wore magnetic foot insoles during the day throughout the trial period. Reduction in the symptoms of burning, numbness, and tingling were especially marked in those cases of neuropathy associated with diabetes.

Based on these results, a far larger randomized, placebo-controlled, follow-up study was performed by the same researchers. This trial enrolled 375 people with peripheral neuropathy caused by diabetes and tested the effectiveness of four months of treatment with magnetic insoles. The results indicated that the insoles produced benefits beyond that of the placebo effect, reducing such symptoms as burning pain, numbness, tingling, and exercise-induced pain.

Surgery support. A double-blind, placebo-controlled study looked at the effect of magnets on healing after plastic surgery. The study examined the use of magnets on twenty persons who had suction lipectomy (liposuction). Magnets contained in patches were placed over the operative region immediately after surgery and left in place for fourteen days. The treatment group experienced statistically significant reduction of pain and swelling on postoperative days one through four, and of discoloration on days one through three, compared with the control group. Another study of 165 people, however, failed to find that the use of static magnets over the surgical incision reduced post-surgical pain. Furthermore, the positioning of static magnets at the acupuncture /acupressure point P6 in persons undergoing ear, nose, and throat or gynecological surgeries reduced nausea and vomiting no better than placebo in a randomized trial.

Low back pain and other forms of chronic musculoskeletal pain. A double-blind, placebo-controlled, crossover trial of fifty-four people with knee or back pain compared a complex static magnet array with a sham magnet array. Participants used either the real or the sham device for twenty-four hours; then, after a seven-day rest period, they used the opposite therapy for another twenty-four hours. Evaluations showed that the 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 forty-three people with chronic knee pain who used fairly high-power but otherwise ordinary static magnets continuously for two weeks. In another placebo-controlled trial, the use of a magnetic knee wrap for twelve weeks was associated with a significant increase in quadriceps (thigh muscle) strength in persons with knee osteoarthritis.

A double-blind, placebo-controlled, crossover study of twenty people who had chronic low back pain for a minimum of six months failed to find any evidence of benefit. However, the alternating-pole magnet used in this study produced a very weak magnetic field. Another study found some benefit that failed to reach statistical significance.

In a double-blind study of 101 people with chronic neck and shoulder pain, the use of a magnetic necklace failed to prove more effective than placebo treatment. Another study failed to find magnetic insoles helpful for heel pain.

Osteoarthritis. A widely publicized twelve-week study of 194
people reportedly found that the use of magnetic bracelets reduced
osteoarthritis pain in the hip and knee. However, the study
actually found statistically similar benefits among participants given a placebo
treatment. The researchers suggest that this failure to show superior effects may
have been caused, in part, by an error: The study utilized weak magnets as the
placebo treatments, but thirty-four persons in the placebo group accidentally
received strong magnets instead. This would tend to decrease the difference in
outcome seen between the treatment and the placebo group and could therefore hide
a real treatment benefit. Nonetheless, this study does not provide evidence that
magnetic bracelets offer any benefit for osteoarthritis beyond that of the placebo
effect.

A much smaller study also failed to find statistically significant benefit, but it was too small to be able to produce statistically meaningful results. Rather, it was designed to evaluate a special placebo magnet device. After the study, researchers polled the participants to see if they could correctly identify whether they had been given the real treatment or the placebo: They could not.

Pelvic pain. A double-blind, placebo-controlled study of 14 women with chronic pelvic pain (from endometriosis or other causes) found no significant benefit when magnets were applied to abdominal trigger points for two weeks. However, statistical analysis showed that it would have been necessary to enroll a larger number of participants to detect an effect. A larger study did find some evidence of benefit after four weeks of treatment, but a high dropout rate and other design problems compromise the meaningfulness of the results. Another small study found possible evidence of benefit in menstrual pain.

Carpal tunnel syndrome. A double-blind, placebo-controlled study
of thirty people with carpal tunnel syndrome found that a
single treatment with a static magnet produced dramatic and long-lasting benefits.
However, identical dramatic benefits were seen in the placebo group. In two more
small, randomized trials, researchers again found that there were no differences
between the treatment and the placebo groups. Both groups experienced similar
improvements in symptoms.

In a small study involving thirty-one people with long-standing carpal tunnel syndrome, a combination of static magnet and pulsed electromagnetic field therapy modestly improved deep pain but had no significant effect on overall pain in a two-month period.

Sports performance. People who undergo intense exercise often experience muscle soreness afterwards. One study tested magnet therapy for reducing this symptom. However, while the use of magnets did reduce muscle soreness, so did placebo treatment, and there was no significant difference between the effectiveness of magnets and placebo. Another study, of more complex design, also failed to find benefit.

Magnetic insoles have been advocated for increasing sports performance. However, a study of fourteen college athletes failed to find that magnetic insoles improved vertical jump, bench squat, forty-yard dash, or performance of a soccer-specific fitness test.

Pulsed electromagnetic field therapy. Pulsed electromagnetic field therapy (PEMF) is quite distinct from magnet therapy itself. (The term “electromagnetic field” does not, in this case, refer to magnetism in the ordinary sense.) Nonetheless, for historical reasons, PEMF is often classified with true magnetic therapies.

Bone has a remarkable capacity to heal from injury. In some cases, though, the broken ends do not join, leading to what is called nonunion fractures. PEMF therapy has been used to stimulate bone repair in nonunion and other fractures since the 1970s; this is a relatively accepted use. More controversially, PEMF has shown promise for osteoarthritis, stress incontinence, and possibly other conditions.

Osteoarthritis. Three double-blind, placebo-controlled studies enrolling more than 350 people suggest that PEMF therapy can improve symptoms of osteoarthritis. For example, a double-blind, placebo-controlled study tested PEMF in eighty-six people with osteoarthritis of the knee and eighty-one people with osteoarthritis of the cervical spine. Participants received eighteen half-hour sessions with either a PEMF machine or a sham device. The treated participants showed significantly greater improvements in disease severity than those given placebo. For both osteoarthritis conditions, benefits lasted for a minimum of one month after treatment was stopped.

A later double-blind trial evaluated low-power, extremely low-frequency PEMF for the treatment of knee osteoarthritis. A total of 176 people received eight sessions of either sham or real treatment for two weeks. The results showed significantly greater pain reduction in the treated group.

Urinary incontinence. Many women experience stress incontinence, the leakage of urine following any action that puts pressure on the bladder. Laughter, physical exercise, and coughing can all trigger this unpleasant occurrence. A recent study suggests that PEMF treatment might be helpful. In this placebo-controlled study, researchers applied high-intensity pulsating magnetic fields to sixty-two women with stress incontinence. The intention was to stimulate the nerves that control the pelvic muscles.

The results showed that one session of magnetic stimulation significantly reduced episodes of urinary leakage over the following week, compared with placebo. In the treated group, 74 percent experienced significant improvement, compared with only 32 percent in the placebo group. Presumably, the high-intensity magnetic field used in this treatment created electrical currents in the pelvic muscles and nerves. This was confirmed by objective examination of thirteen participants, which found that magnetic stimulation was increasing the strength of closure at the exit from the bladder. However, there was one serious flaw in this study: It does not appear to have been double-blind. Researchers apparently knew which participants were getting real treatment and which were not and, therefore, might have unconsciously biased their observations to conform to their expectations. Thus, the promise of electromagnetic therapy for stress incontinence still needs to be validated in properly designed trials.

Similarly, magnetic stimulation has been studied for the treatment of bed-wetting (nocturnal enuresis). In a small preliminary study, the use of PEMF day and night for two months was helpful in girls.

Multiple sclerosis. A two-month, double-blind, placebo-controlled
study of thirty people with multiple sclerosis was conducted using
a PEMF device. Participants were instructed to tape the device to one of three
different acupuncture points on the shoulder, back, or hip. The study found
statistically significant improvements in the treatment group, most notably in
bladder control, hand function, and muscle spasticity. Benefits were seen in
another small study too.

Erectile dysfunction. In a three-week, double-blind, placebo-controlled trial, twenty men with erectile dysfunction received PEMF therapy or placebo. The magnetic therapy was administered by means of a small box worn near the genital area and kept in place as continuously as possible during the study period; neither participants nor observers knew whether the device was activated or not. The results showed that the use of PEMF significantly improved sexual function compared with placebo.

Migraines. In a double-blind trial, forty-two people with
migraine
headaches were given treatment with real or placebo PEMF
therapy to the inner thighs for one hour, five times per week for two weeks. The
results showed benefits in headache frequency and severity. However, the study
design was rather convoluted and nonstandard, so the results are difficult to
interpret.

Postoperative pain. In a small, randomized trial, eighty women undergoing breast augmentation surgery were divided into three groups. The first group received PEMF therapy for seven days after surgery to both breasts, the second group received fake PEMF therapy to both breasts as a control, and the third group received real and fake PEMF therapy to either breast. Compared to the control, women receiving PEMF therapy reported significantly less discomfort and used less pain medications by the third postoperative day.

Electromagnetic therapy. Unlike PEMF, repetitive transcranial magnetic stimulation (rTMS) involves magnetic fields and is, therefore, more closely related to standard magnet therapy. rTMS, which involves applying low-frequency magnetic pulses to the brain, has been investigated for treating emotional illnesses and other conditions that originate in the brain. The results of preliminary studies have been generally promising.

Depression. About twenty small studies have evaluated rTMS for the treatment of depression, including severe depression that does not respond to standard treatment and the depressive phase of bipolar illness, and most found it effective. In one of these studies, seventy people with major depression were given rTMS or sham rTMS in a double-blind setting of two weeks. The results showed that participants who had received actual treatment experienced significantly greater improvement than did those receiving sham treatment. In a far larger study involving 301 depressed persons, none of whom were being treated with antidepressant medications, real rTMS was significantly more effective than fake rTMS after four to six weeks of treatment.

In another trial involving ninety-two elderly persons whose depression had been linked to poor blood flow to the brain (vascular depression), actual rTMS was significantly more effective than sham rTMS. Benefits were more notable in younger participants. In a particularly persuasive piece of evidence, researchers pooled the results of thirty double-blind trials involving 1,164 depressed persons and determined that real rTMS was significantly more effective than sham rTMS.

Two separate studies suggest that rTMS may be an effective additional treatment
for the 20 to 30 percent of depressed people for whom conventional drug therapy is
not successful. Another group of researchers pooled the results of twenty-four
studies involving 1,092 persons and found rTMS to be more effective than sham for
treatment-resistant depression. Electroconvulsive therapy (shock
treatment) is often used for people in this category, but
rTMS may be an equally effective alternative.

Epilepsy. In a double-blind, placebo-controlled trial,
twenty-four people with epilepsy (technically, partial complex
seizures or secondarily generalized seizures) not fully responsive to drug
treatment were given treatment with rTMS or sham rTMS twice daily for one week.
The results showed a mild reduction in seizures among the people given real rTMS.
However, the benefits rapidly disappeared when treatment was stopped. Similarly
short-lived effects were seen in an open trial.

Schizophrenia. A double-blind, placebo-controlled, crossover
trial looked at the use of low-frequency rTMS in twelve people diagnosed with
schizophrenia and manifesting frequent and
treatment-resistant auditory hallucinations (hearing voices). Participants
received rTMS for four days, with the length of treatment building from four
minutes on the first day to sixteen minutes on the fourth day. Active stimulation
significantly reduced the incidence of auditory hallucinations compared with sham
stimulation. The extent of the benefit varied widely, lasting from one day in one
participant to two months in another. Possible benefits were seen in other small
studies. Researchers pooling the results of six controlled trials, which involved
232 persons with schizophrenia resistant to conventional treatment, found that
real, low-frequency rTMS was significantly better at reducing auditory
hallucinations than sham rTMS.

Parkinson’s disease. In a double-blind, placebo-controlled trial
of ninety-nine people with Parkinson’s disease, real rTMS was more
effective than sham rTMS delivered in eight weekly treatments. Similar benefits
were seen in three other small studies. Even more encouraging, the combined
results of ten randomized trials in persons with Parkinson’s indicated significant
benefit for rTMS (using higher frequencies).

Chronic pain syndromes. rTMS technology has also been applied to areas other than the brain. Myofascial pain syndrome is a condition similar to fibromyalgia but is more localized. Whereas fibromyalgia involves tender trigger points all over the body, myofascial pain syndrome involves trigger points clustered in one portion of the body only. One controlled trial found indications that a form of repetitive magnetic stimulation applied to the painful area may be effective for myofascial pain syndrome of the trapezius muscle.

In a placebo-controlled trial involving sixty-one people with long-standing diabetes, low-frequency repetitive magnetic stimulation failed to diminish the pain associated with diabetic peripheral neuropathy. However, in another study involving twenty-eight people with peripheral neuropathy, high-frequency rTMS applied to the brain was more effective at reducing pain and improving quality of life than was fake rTMS.

Tinnitus. One preliminary study found indications that rTMS may be helpful for tinnitus (ringing in the ear).

Post-traumatic stress disorder. A small, double-blind, placebo-controlled study found that the use of rTMS may be able to reduce symptoms of post-traumatic stress disorder.

Cigarette addiction. A small, double-blind, placebo-controlled study found evidence that rTMS may reduce the craving for cigarettes in people attempting to quit smoking.

Obsessive-compulsive disorder. A double-blind, placebo-controlled study of eighteen people with obsessive-compulsive disorder found no evidence of benefit with rTMS.

Amyotrophic lateral sclerosis. Amyotrophic lateral sclerosis, also called Lou Gehrig’s disease, is a nerve disorder that causes progressive muscle weakness. A small pilot study hinted that rTMS may be beneficial at least temporarily.

Andre-Obadia, N., et al. “Pain Relief by rTMS: Differential Effect of Current Flow but No Specific Action on Pain Subtypes.” Neurology 71 (2008): 833-840.

Bretlau, L. G., et al. “Repetitive Transcranial Magnetic Stimulation (rTMS) in Combination with Escitalopram in Patients with Treatment-Resistant Major Depression.” Pharmacopsychiatry 41 (2008): 41-47.

Cepeda, M. S., et al. “Static Magnetic Therapy Does Not Decrease Pain or Opioid Requirements.” Anesthesia and Analgesia 104 (2007): 290-294.

Chen, C. Y., et al. “Effect of Magnetic Knee Wrap on Quadriceps Strength in Patients with Symptomatic Knee Osteoarthritis.” Archives of Physical Medicine and Rehabilitation 89 (2008): 2258-2264.

Colbert, A. P., et al. “Static Magnetic Field Therapy for Carpal Tunnel Syndrome.” Archives of Physical Medicine and Rehabilitation 91 (2010): 1098-1104.

Heden, P., and A. A. Pilla. “Effects of Pulsed Electromagnetic Fields on Postoperative Pain: A Double-Blind Randomized Pilot Study in Breast Augmentation Patients.” Aesthetic Plastic Surgery 32 (2008): 660-666.

Klaiman, P., et al. “Magnetic Acupressure for Management of Postoperative Nausea and Vomiting.” Minerva Anestesiologica 74 (2008): 635-642.

Pittler, M. H., E. M. Brown, and E. Ernst. “Static Magnets for Reducing Pain.” CMAJ: Canadian Medical Association Journal 177 (2007): 736-742.

Wrobel, M. P., et al. “Impact of Low Frequency Pulsed Magnetic Fields on Pain Intensity, Quality of Life, and Sleep Disturbances in Patients with Painful Diabetic Polyneuropathy.” Diabetes and Metabolism 34 (2008): 349-354.