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;
they further concluded that current evidence suggests that, for some pain-related conditions, static magnets are, in fact, 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 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.
trial of 64 people with
of the knee compared the effects of strong alternating polarity magnets (see
Types of Magnet Therapy and Their Uses
for definition) with the effects of a deliberately weak unipolar magnet.
Researchers used the weakened magnet as a control group so that participants wouldn’t find it easy to break the blind by testing the magnetism of their treatment.
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
. Two out 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."
A double-blind, placebo-controlled study of 50 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 45 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% of the participants reported improvement, compared to 19% in the placebo group.
A 6-month, double-blind, placebo-controlled trial of 119 people with
compared two commercially available magnetic mattress pads against 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 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.
The women slept on magnetic mattress pads (or sham pads for the control group) every night for 4 months. Of the 25 women who completed the trial, participants sleeping on the experimental mattress pads experienced a significant decrease in pain and fatigue compared to 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.
A 4-month, double-blind, placebo-controlled crossover study of 19 people with
found a significant reduction in symptoms compared to 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 4 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.
A double-blind, placebo-controlled study looked at the effect of magnets on healing after plastic
The study examined the use of magnets on 20 patients who had suction lipectomy (commonly known as liposuction). Magnets contained in patches were placed over the operative region immediately after surgery and left in place for 14 days. The treatment group experienced statistically significant reduction of pain and swelling on postoperative days 1-4 and in discoloration on days 1-3 compared to the control group.
Another study of 165 people, however, failed to find that use of static magnets over the surgical incision reduced post surgical pain.
Furthermore, the positioning of static magnets at the
/acupressure point P6 in patients undergoing ear, nose, and throat (ENT) or gynaecological 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 54 people with knee or
compared a complex static magnet array against a sham magnet array.
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.
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.
In yet another trial, 62 people were randomized to wear a magnetic therapy device on the neck and shoulder area or a sham device. Those in the treatment group experienced an improvement in pain and stiffness over those in the sham group.
On the other hand, 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.
(The alternating pole magnet used in this study produced a very weak magnetic field, however.)
Another study found hints of benefit that failed to reach statistical significance.
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.
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 due, in part, to an unfortunate error: the study utilized weak magnets as the placebo treatments, but 34 patients 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, as matters currently stand, 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'd been given the real treatment or the placebo: they could not.
A double-blind, placebo-controlled study of 14 women with chronic pelvic pain (due to
or other causes) found no significant benefit when magnets were applied to abdominal trigger points for 2 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 4 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
Carpal Tunnel Syndrome
A double-blind, placebo-controlled study of 30 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 31 hands with long-standing CTS, a combination of static magnet and pulses electromagnetic field (see below) therapy modestly improved “deep” pain, but had no significant effect on overall pain over a 2-month period.
People who undergo intense exercise often experience muscle soreness afterwards. (See
Sports and Fitness Support: Enhancing Recovery
.) One study tested magnet therapy for reducing this symptom.
However, while 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 also been advocated for increasing
. However, a study of 14 college athletes failed to find that magnetic insoles improved vertical jump, bench squat, 40-yard dash, or a soccer-specific fitness test performance.
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.
Three double-blind, placebo-controlled studies enrolling a total of more than 350 people suggest that pulsed electromagnetic field therapy can improve symptoms of
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.
Participants received 18 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 at least 1 month after treatment was stopped.
A more recent double-blind trial evaluated low-power, extremely low-frequency pulsed electromagnetic fields for the treatment of knee osteoarthritis.
A total of 176 people received eight sessions of either sham or real treatment over a period of 2 weeks. The results showed significantly greater pain reduction in the treated group.
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 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 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
Why Does This Database Rely on Double-blind Studies?
) 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 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
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.
A review of 6 studies supported that magnetic metal mats, used for 8 minutes, 2 times per day, may be useful in decreasing fatigue, but not depression associated with MS. There was inconclusive evidence about usesfulness to manage other symptoms, such as bladder control, cognition, fatigue, or mobility.
In a 3-week, double-blind, placebo-controlled trial, 20 men with
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 over the study period; neither participants nor observers knew whether the device was actually activated or not. The results showed that use of PEMF significantly improved sexual function compared to placebo.
In a double-blind trial, 42 people with
were given treatment with real or placebo pulsed electromagnetic therapy to the inner thighs for 1 hour, 5 times per week for 2 weeks.
The results showed benefits in headache frequency and severity. However, the study design was rather convoluted and nonstandard, and, therefore, the results are difficult to interpret.
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
(including severe depression that does not respond to standard treatment, as well as the depressive phase of
), and most found it effective.
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.
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 patients, none of whom were being treated with antidepressant medications, real rTMS was significantly more effective than fake rTMS after 4-6 weeks of treatment.
In a much smaller trial involving 45 subjects, researchers found that rTMS is more effective than sham rTMS as an add-on treatment to medication in people with moderate to severe depression (including those with psychotic symptoms).
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.
Another group of researchers pooled the results of 24 studies involving 1,092 patients and found rTMS to be more effective than sham for treatment resistant depression.
ECT (electroconvulsive therapy, or shock treatment) is often used for people who fall in this category, but rTMS may be an equally effective alternative.
In a double-blind, placebo-controlled trial, 24 people with
(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 a 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.
A double-blind, placebo-controlled crossover trial looked at the use of low-frequency rTMS in 12 people diagnosed with
and manifesting frequent and treatment-resistant auditory hallucinations (hearing voices).
Participants received rTMS for 4 days, with length of treatment building from 4 minutes on the first day to 16 minutes on the fourth day. Active stimulation significantly reduced the incidence of auditory hallucinations compared to sham stimulation. The extent of the benefit varied widely, lasting from 1 day in one participant to 2 months in another. Possible benefits were seen in other small studies, as well.
Researchers pooling the results of 6 controlled trials, which involved a total of 232 patients with schizophrenia resistant to conventional treatment, found that real low-frequency rTMS was significantly better at reducing auditory hallucinations compared to sham rTMS.
A review of 20 randomized trials with 470 patients found that real rTMS improved motor symptoms more effectively than sham rTMS. Treatment times ranged from 1 day to 12 weeks. In these trials, the most improvement was also seen with high-frequency rTMS.106,40,64,71,83,90 However, a subsequent small, randomized study involving 23 people did not find promising results.
Compared to placebo, 10 days of transcranial electrostimulation did not improve the symptoms of Parkinson's disease.
Chronic Pain Syndromes
rTMS technology has also been applied to areas other than the brain. Myofascial pain syndrome is a condition similar to
, but more localized. While 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 trail involving 61 people with long-standing diabetes, low-frequency repetitive magnetic stimulation failed to diminish the pain associated with
diabetic peripheral neuropathy
Interestingly, however, in another study involving 28 people with peripheral neuropathy, high frequency rTMS applied to the brain was more effective at reducing pain and improving quality of life than fake rTMS.
A preliminary study found indications that rTMS may be helpful for
(ringing in the ear).
However, a subsequent review of 5 randomized trials comparing rTMS to sham rTMS in 233 people with tinnitus found limited evidence to support its use for this condition.
The authors highlighted the need for more studies with larger sample sizes.
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.
A very small, double-blind, placebo-controlled study found evidence that rTMS may reduce craving for cigarettes in people attempting to
A double-blind, placebo-controlled study of 18 people with
found no evidence of benefit with rTMS.
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.
Chronic Regional Pain Syndrome
People with chronic regional pain syndrome (CRPS) may have a feeling of aching or burning in their arms or legs. One small study included 23 people with CRPS who were already getting conventional treatment (eg, pain medication, physical therapy) for pain in their arms.
The groups were randomized to receive either real or sham rTMS for 10 daily sessions. Those who received the real magnet therapy experienced a significant reduction in pain during the 10 days of treatment, but the effect did not persist.