• Static Magnets:
• Pulsed Electromagnetic Therapy—PEMF:
• Repetitive Transcranial Magnet Therapy—rTMS:
• Static Magnets:
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 myriads of healing benefits.
Despite this enthusiasm, as yet there is little scientific evidence to support the use of magnets for any medical condition. However, some small studies completed in the last few years suggest that various forms of magnet therapy might have a therapeutic effect in certain conditions. More studies are underway.
History of Magnet Therapy
Magnet therapy has a long history in traditional folk medicine. Reliable documentation tells us that Chinese doctors believed in the therapeutic value of magnets at least 2,000 years ago, and probably earlier than that. In sixteenth century Europe, Paracelsus used magnets to treat a variety of ailments. Two centuries later, 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—again, 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 (detailed in the
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 and tesla. One tesla equals 10,000 gauss. A refrigerator magnet, for example, is around 200 gauss. Therapeutic magnets measure anywhere from 200 to 10,000 gauss, but the most commonly used measure 400 to 800 gauss.
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
How Does Magnet Therapy Work?
Many commercial magnets have such a weak field that it is hard to believe they could affect the body at all. Some, however, are quite powerful and could conceivably cause effects at some depth. Nonetheless, biophysicists are skeptical that static magnets could significantly affect the body. (The moving magnetic fields of rTMS and pulsed electromagnetic therapy [PEMF] act differently, and there is little doubt that they can affect nerve tissue and possibly other parts of the body as well.)
A commonly held misconception is that magnets attract the iron in blood cells, thus moving the blood and stimulating circulation. However, the iron in the blood is not in a magnetic form. Static magnets could affect charged particles in the blood, nerves, and cell membranes or subtly alter biochemical reactions, although whether the effect is strong enough to make a difference remains to be shown. 1
What Is the Scientific Evidence for Magnet Therapy?
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 as yet there is no meaningful evidence that they are effective;
: 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 applied to 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 patients have been found unable to identify as fake treatments.
After 1 week of therapy, 68% of the participants using the strong magnets (called the treatment group) reported relief, compared to 27% in the control group. This difference was
A double-blind, placebo-controlled study of 50 people with post-polio syndrome found evidence that magnets are effective for relieving pain.
A 6-month, double-blind, placebo-controlled trial of 119 people with
On average, participants in all groups showed improvement over the 6 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.
A previous double-blind, placebo-controlled study of 30 women with fibromyalgia did find significant improvement with magnets compared to placebo.
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.
A 4-month, double-blind, placebo-controlled crossover study of 19 people with
Based on these results, a far larger randomized, placebo-controlled, follow-up study was performed by the same researchers.
A double-blind, placebo-controlled study looked at the effect of magnets on healing after plastic
Furthermore, the positioning of static magnets at the
Low Back Pain and Other Forms of Chronic Musculoskeletal Pain
A double-blind, placebo-controlled crossover trial of 54 people with knee or
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.
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.
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.
Another study failed to find magnetic insoles helpful for heel pain.
A widely publicized 12-week study of 194 people reportedly found that use of magnetic bracelets reduced osteoarthritis pain in the hip and knee.
A much smaller study also failed to find statistically significant benefit, but it was too small to be able to produce statistically meaningful results.
A double-blind, placebo-controlled study of 14 women with chronic pelvic pain (due to
Carpal Tunnel Syndrome
A double-blind, placebo-controlled study of 30 people with
People who undergo intense exercise often experience muscle soreness afterwards. (See
Magnetic insoles have also been advocated for increasing
Pulsed Electromagnetic Field Therapy (PEMF)
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, it is often classified together with true magnetic therapies. Because of that, we discuss it here.
Bone has a remarkable capacity to heal from injury. In some cases, though, the broken ends do not join, called non-union fractures. PEMF therapy has been used to stimulate bone repair in non-union and other fractures since the 1970s; this is a relatively accepted use and will not be discussed here. More controversially, PEMF has shown promise for osteoarthritis, stress incontinence, and possibly other conditions as well.
For example, a double-blind, placebo-controlled study tested PEMF in 86 people with osteoarthritis of the knee and 81 with osteoarthritis of the cervical spine.
A more recent double-blind trial evaluated low-power, extremely low-frequency pulsed electromagnetic fields for the treatment of knee osteoarthritis.
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 62 women with stress incontinence.
The results showed that one session of magnetic stimulation significantly reduced episodes of urinary leakage over the following week, compared to placebo. In the treated group, 74% experienced significant improvement, compared to only 32% 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 13 patients, which found that magnetic stimulation was in fact 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. (For more information on why this is important, see
Similarly, magnetic stimulation has been studied for the treatment of bed-wetting (nocturnal eneuresis). In a small preliminary study, the use of PEMF day and night for 2 months was helpful in girls.
A 2-month, double-blind, placebo-controlled study of 30 people with
In a 3-week, double-blind, placebo-controlled trial, 20 men with
In a double-blind trial, 42 people with
In a small, randomized trial, 80 women undergoing breast augmentation surgery were divided into three groups. The first group received PEMF therapy for 7 days postsurgically 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: Repetitive Transcranial Magnetic Stimulation
Unlike PEMF, repetitive transcranial magnetic stimulation (rTMS) does in fact involve magnetic fields, and is, therefore, more closely related to standard magnet therapy. It involves applying low-frequency magnetic pulses to the brain. rTMS has been investigated for treating emotional illnesses and other conditions that originate in the brain. The results of preliminary studies have been generally promising.
About 20 small studies have evaluated rTMS for the treatment of
In one of these studies, 70 people with major depression were given rTMS or sham rTMS in a double-blind setting over a period of 2 weeks.
In another trial involving 92 older patients whose depression had been linked to poor blood flow to the brain (so-called vascular depression), actual rTMS was significantly more effective than sham rTMS. Benefits were more notable in younger patients.
In a particularly persuasive piece of evidence, researchers pooled the results of 30 double-blind trials involving 1,164 depressed patients and determined that real rTMS is significantly more effective than sham (fake) rTMS.
Two separate studies suggest that rTMS may be an effective additional treatment for the 20%-30% of depressed people for whom conventional drug therapy is not successful.
In a double-blind, placebo-controlled trial, 24 people with
A double-blind, placebo-controlled crossover trial looked at the use of low-frequency rTMS in 12 people diagnosed with
In a double-blind, placebo-controlled trial of 99 people with
Chronic Pain Syndromes
rTMS technology has also been applied to areas other than the brain. Myofascial pain syndrome is a condition similar to
In a placebo-controlled trail involving 61 people with long-standing diabetes, low-frequency repetitive magnetic stimulation failed to diminish the pain associated with
diabetic peripheral neuropathy
Post-traumatic Stress Disorder
A small, double-blind, placebo-controlled study found that use of rTMS may be able to reduce symptoms of post-traumatic stress disorder.
Myotropic Lateral Sclerosis (Lou Gerhig’s Disease)
Amyotrophic lateral sclerosis (ALS) is a nerve disorder that causes progressive muscle weakness. A small pilot study hinted that rTMS may be beneficial at least temporarily.
How to Use Magnet Therapy
The following is a brief description of the use of magnet therapy. However, keep in mind that the current ways that magnets are used have yet to be fully evaluated by long-term clinical testing.
A full medical evaluation is advisable before using magnets. You don't want to be treating a painful back with magnets if the underlying cause of pain is a fracture or a tumor! Other concerns are discussed in the Safety Issues
Types of Magnets
If you have decided you do wish to try magnet therapy, you will have to choose among many different types of magnets and magnetic devices on the market today. There are a number of theories on the size and type of magnets to use and where to apply them, based on the type of condition being treated and other factors. Because unipolar magnets have greater depth of magnetic field penetration, some researchers consider these more effective in treating deeper tissues. Conversely, it is considered that alternating-pole magnet devices might be more effective at stimulating surface tissue. Thus, it might be appropriate to use a unipolar high-gauss magnet for low back pain that originates deep in the tissue and an alternating-pole configuration for an injury closer to the surface, such as a wrist sprain. However, there is no meaningful scientific evidence to support these distinctions.
In addition, some practitioners hold that the north side of the magnet calms and the south side excites, and that using the correct side of the magnet is crucial. However, from a scientific perspective, it is difficult to see how there could be any difference between the two poles of the magnet in terms of the effect upon body tissue.
There is general consensus that the magnet should be placed as close to the affected part of the body as possible. This can be done by taping the magnet to the skin, slipping the magnet inside a bandage over the affected area, or using a wrap device that has magnets embedded in it.
Tape holding magnets to the body might irritate the skin; in addition, some research scientists and practitioners suspect that the body may accommodate to the magnetic field over time, thus reducing the therapeutic effect. In order to prevent both the irritation and the accommodation, practitioners usually recommend intermittent use, such as 5 days on, 2 days off; or 12 hours on, 12 hours off.
Magnetic Devices Available
Manufacturers make a wide range of magnetic devices. For treating large areas of the body, wraps and belts containing magnets are available. Wraps are specifically designed for the wrist, elbow, knee, ankle, neck, shoulder, and back, and are often made out of thermal material to have the added effect of warming the area. These wraps are often recommended in cases of injury and arthritis where heat feels better. Proponents of magnet therapy often recommend the use of magnetic mattress pads and mattresses for people with problems affecting several areas of the body, such as fibromyalgia or arthritis; they also recommend magnetic mattress pads for insomnia and fatigue.
Proponents of magnet therapy recommend magnetic foot insoles for people with diabetic peripheral neuropathy, leg aches and pains, circulatory problems of the lower extremities, or foot injuries and problems, and for people who stand all day.
Magnetic necklaces are said to be useful for neck and shoulder pain as well as for generalized aches and pains, and magnetic bracelets are advocated for wrist pain and general problems.
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. 31
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.
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.
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Last reviewed April 2009 by EBSCO CAM Review Board
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