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Magnets
Magnets are objects that produce a type of energy called magnetic fields. Magnets are widely marketed to treat or ease the symptoms of various diseases and conditions, including pain. This Research Report provides an overview of the use of magnets for pain, summarizes current scientific knowledge about their effectiveness for this purpose, and suggests additional sources of information. Terms are defined in the "Definitions" section.
Key Points
The vast majority of magnets marketed to consumers to treat pain are of a type called static (or permanent) magnets, because the resulting magnetic fields are unchanging. The other magnets used for health purposes are called electromagnets, because they generate magnetic fields only when electrical current flows through them. Currently, electromagnets are used primarily under the supervision of a health care provider or in clinical trials.
Scientific research so far does not firmly support a conclusion that magnets of any type can relieve pain. However, some people do experience some relief. Various theories have been proposed as to why, but none has been scientifically proven (see Question 5).
Clinical trials in this area have produced conflicting results (see Question 8). Many concerns exist regarding the quality and rigor of the studies conducted to date, leading to a call for additional, higher quality, and larger studies.
The U.S. Food and Drug Administration (FDA) has not approved the marketing of magnets with claims of benefits to health (such as "relieves arthritis pain"). The FDA and the Federal Trade Commission (FTC) have taken action against many manufacturers, distributors, and Web sites that make claims not supported scientifically about the health benefits of magnets.
It is important that people inform their health care providers about any therapy they are currently using or considering, including magnets. This is to help ensure a safe and coordinated course of care.
1. What are magnets?
Magnets are objects that produce a type of energy called magnetic fields. All magnets possess a property called polarity--that is, a magnet's power of attraction is strongest at its opposite ends, usually called the north and south poles. The north and south poles attract each other, but north repels north and south repels south. All magnets attract iron.
Magnets come in different strengths, most often measured in units called gauss (G). For comparison purposes, the Earth has a magnetic field of about 0.5 G; refrigerator magnets range from 35 to 200 G; magnets marketed for the treatment of pain are usually 300 to 5,000 G; and MRI (magnetic resonance imaging) machines widely used to diagnose medical conditions noninvasively produce up to 200,000 G.1
The vast majority of magnets marketed to consumers for health purposes (see the box below) are of a type called static (or permanent) magnets. They have magnetic fields that do not change.
Examples of Products Using Magnets
Shoe insoles
Heel inserts
Mattress pads
Bandages
Belts
Pillows and cushions
Bracelets and other jewelry
Headwear
The other magnets used for health purposes are called electromagnets, because they generate magnetic fields only when electrical current flows through them. The magnetic field is created by passing an electric current through a wire coil wrapped around a magnetic core. Electromagnets can be pulsed--that is, the magnetic field is turned on and off very rapidly.
2. Is the use of magnets considered conventional medicine or complementary and alternative medicine?
Conventional medicine and complementary and alternative medicine (CAM) are defined in the box below.
About CAM and Conventional Medicine
Complementary and alternative medicine (CAM) is a group of various medical and health care systems, practices, and products that are not presently considered to be part of conventional medicine. Conventional medicine is medicine as practiced by holders of M.D. (medical doctor) or D.O. (doctor of osteopathy) degrees and by allied health professionals, such as physical therapists, psychologists, and registered nurses. To find out more, see the NCCAM fact sheet "What Is Complementary and Alternative Medicine?"
There are some uses of electromagnets within conventional medicine. For example, scientists have found that electromagnets can be used to speed the healing of bone fractures that are not healing well.2,3 Even more commonly, electromagnets are used to map areas of the brain. However, most uses of magnets by consumers in attempts to treat pain are considered CAM, because they have not been scientifically proven and are not part of the practice of conventional medicine.
3. What is the history of the discovery and use of magnets to treat pain?
Magnets have been used for many centuries in attempts to treat pain.a By various accounts, this use began when people first noticed the presence of naturally magnetized stones, also called lodestones. Other accounts trace the beginning to a shepherd noticing that the nails in his sandals were pulled out by some stones. By the third century A.D., Greek physicians were using rings made of magnetized metal to treat arthritis and pills made of magnetized amber to stop bleeding. In the Middle Ages, doctors used magnets to treat gout, arthritis, poisoning, and baldness; to probe and clean wounds; and to retrieve arrowheads and other iron-containing objects from the body.
In the United States, magnetic devices (such as hairbrushes and insoles), magnetic salves, and clothes with magnets applied came into wide use after the Civil War, especially in some rural areas where few doctors were available. Healers claimed that magnetic fields existed in the blood, organs, or elsewhere in the body and that people became ill when their magnetic fields were depleted. Thus, healers marketed magnets as a means of "restoring" these magnetic fields. Magnets were promoted as cures for paralysis, asthma, seizures, blindness, cancer, and other conditions. The use of magnets to treat medical problems remained popular well into the 20th century. More recently, magnets have been marketed for a wide range of diseases and conditions, including pain, respiratory problems, high blood pressure, circulatory problems, arthritis, rheumatism, and stress.
a Sources for this historical discussion include references 1, 4, and 5.
4. How common is the use of magnets to treat pain?
A 1999 survey of patients who had rheumatoid arthritis, osteoarthritis, or fibromyalgia and were seen by rheumatologists reported that 18 percent had used magnets or copper bracelets, and that this was the second-most-used CAM therapy by these patients, after chiropractic.6 One estimate places Americans' spending on magnets to treat pain at $500 million per year; the worldwide estimate is $5 billion.7 Many people purchase magnets in stores or over the Internet to use on their own without consulting a health care provider.
5. What are some examples of theories and beliefs about magnets and pain?
Some examples of theories and beliefs about using magnets to treat pain are listed below. These range from theories proposed by scientific researchers to claims made by magnet manufacturers. It is important to note that while the results for some of the findings from the scientific studies have been intriguing, none of the theories or claims below has been conclusively proven. For the following, summaries of research from peer-reviewed medical and scientific journals appear in Appendix I:
Static magnets might change how cells function.
Magnets might alter or restore the equilibrium (balance) between cell death and growth.
Because it contains iron, blood might act as a conductor of magnetic energy. Static magnets might increase the flow of blood and, therefore, increase the delivery of oxygen and nutrients to tissues.
Weak pulsed electromagnets might affect how nerve cells respond to pain.
Pulsed electromagnets might change the brain's perception of pain.
Electromagnets might affect the production of white blood cells involved in fighting infection and inflammation.
Here are two other theories and beliefs:
Magnets might increase the temperature of the area of the body being treated.
"Magnetizing" or "re-magnetizing" drinking water or other beverages might allow them to hydrate the body better and flush out more "toxins" than ordinary drinking water.
6. How are static magnets used in attempts to treat pain?
Static magnets are usually made from iron, steel, rare-earth elements, or alloys. Typically, the magnets are placed directly on the skin or placed inside clothing or other materials that come into close contact with the body. Static magnets can be unipolar (one pole of the magnet faces or touches the skin) or bipolar (both poles face or touch the skin, sometimes in repeating patterns).8 Some magnet manufacturers make claims about the poles of magnets--for example, that a unipolar design is better than a bipolar design, or that the north pole gives a different effect from the south pole. These claims have not been scientifically proven.1,9
A small number of rigorous scientific studies have examined the efficacy of static magnets in treating pain. This evidence is discussed in Question 8 and Appendices II and III.
7. How are electromagnets used in attempts to treat pain?
Electromagnets were approved by the FDA in 1979 to treat bone fractures that have not healed well.2,3 Researchers have been studying electromagnets for painful conditions, such as knee pain from osteoarthritis, chronic pelvic pain, problems in bones and muscles, and migraine headaches.3,9-12 However, these uses of electromagnets are still considered experimental by the FDA and have not been approved. Currently, electromagnets to treat pain are being used mainly under the supervision of a health care provider and/or in clinical trials.
An electromagnetic therapy called TMS (transcranial magnetic stimulation) is also being studied by researchers. In TMS, an insulated coil is placed against the head, near the area of the brain to be examined or treated, and an electrical current generates a magnetic field into the brain. Currently, TMS is most often used as a diagnostic tool, but research is also under way to see whether it is effective in relieving pain.13,14 A type of TMS called rTMS (repetitive TMS) is believed by some to produce longer lasting effects and is being explored for its usefulness in treating chronic pain, facial pain, headache, and fibromyalgia pain.15,16 A related form of electromagnetic therapy is rMS (repetitive magnetic stimulation). It is similar to rTMS except that the magnetic coil is placed on or near a painful area of the body other than the head. This therapy is being studied as a treatment for musculoskeletal pain.17,18
8. What is known from the scientific evidence about the effectiveness of magnets in treating pain?
Overall, the research findings so far do not firmly support claims that magnets are effective for treatment of pain.
Findings from Reviews of Scientific Studies
Reviews take a broad look at the findings from a group of individual research studies. Such reviews are usually either a general review, a systematic review, or a meta-analysis. There are not many reviews available on CAM uses of magnets to treat pain. Appendix II provides examples of six reviews published from August 1999 through August 2003 in English in the National Library of Medicine's MEDLINE database.
Often, these reviews compared what is known from the clinical trials of magnets for painful conditions to what is known from conventional treatments or from other CAM treatments for the same condition(s).
One review found that static magnetic therapy may work for certain conditions but that there is not adequate scientific support to justify its use.1
Three reviews found that electromagnetic therapy showed promise for the treatment of some, but not all, painful conditions, and that more research is needed.9,19,20 One of these reviews also looked at two randomized clinical trials (RCTs) of static magnets.9 One reported significant pain relief in subjects using magnets, but the other did not.
Another review concluded that TMS has an effect on the central nervous system that might relieve chronic pain and, therefore, should be studied further.14
The remaining review found no studies on magnets for neck pain and stated that rigorous studies are much needed.21
It is important to note that the reviews pointed out problems with the rigor of most research on magnets for pain.9,14,19,20 For example, many of the clinical trials involved a very small number of participants, were conducted for very short durations (e.g., one study applied a magnet a total of one time for 45 minutes), and/or lacked a placebo or sham group for comparison to the magnet group.19,20 Thus, the results of many trials may not be truly meaningful. Most reviews stated that more and better quality research is needed before magnets' effectiveness can be adequately judged.
Findings from Clinical Trials
The studies in Appendix III give an overview of scientific research from 15 RCTs published in English from January 1997 through March 2004 and cataloged in the National Library of Medicine's MEDLINE database. These trials studied CAM uses of static magnets or electromagnets for various kinds of pain.
The results of trials of static magnets have been conflicting. Four of the nine static magnet trials analyzed found no significant difference in pain relief from using a magnet compared with sham treatment or usual medical care.7,8,22,23 Four trials did find a significant difference, with greater benefit seen from magnets.24-27 The remaining trial compared only a weaker strength magnet to a stronger magnet, and found benefit from both (there was no difference between groups in how much benefit).28
Trials of electromagnets yielded more consistent results. Five out of six trials found that these magnets significantly reduced pain.10,11,17,18,29 The sixth found a significant benefit to physical function from using electromagnets, but not to pain or stiffness.30
Some study authors suggested that a placebo effect could have been responsible for the pain relief that occurred from magnets.22,30
While criticizing many of these studies, it is fair to say that testing magnets in clinical trials has presented challenges. For example, it can be difficult to design a sham magnet that appears exactly like an active magnet. Also, there has been concern about how many participants have tried to determine whether they have been assigned an active magnet (for example, by seeing whether a paperclip would be attracted to it); this knowledge could affect how meaningful a trial's results are.
9. Are there scientific controversies associated with using magnets for pain?
Yes, there are many controversies. Examples include:
The mechanism(s) by which magnets might relieve pain have not been conclusively identified or proven.
Pain relief while using a magnet may be due to reasons other than the magnet. For example, there could be a placebo effect or the relief could come from whatever holds the magnet in place, such as a warm bandage or a cushioned insole.22,24
Opinions differ among manufacturers, health care providers who use magnetic therapy, and others about which types of magnets (strength, polarity, length of use, and other factors) should be used and how they should be used in studies to give the most definitive answers.
Actual magnet strengths can vary (sometimes widely) from the strengths claimed by manufacturers. This can affect scientists' ability to reproduce the findings of other scientists and consumers' ability to know what strength magnet they are actually using.26,31,32
10. Have any side effects or complications occurred from using magnets for pain?
The kinds of magnets marketed to consumers are generally considered to be safe when applied to the skin.7 Reports of side effects or complications have been rare. One study reported that a small percentage of participants had bruising or redness on their skin where a magnet was worn.33
Manufacturers often recommend that static magnets not be used by the following people1:
Pregnant women, because the possible effects of magnets on the fetus are not known.
People who use a medical device such as a pacemaker, defibrillator, or insulin pump, because magnets may affect the magnetically controlled features of such devices.
People who use a patch that delivers medication through the skin, in case magnets cause dilation of blood vessels, which could affect the delivery of the medicine. This caution also applies to people with an acute sprain, inflammation, infection, or wound.
There have been rare cases of problems reported from the use of electromagnets. Because at present these are being used mainly under the supervision of a health care provider and/or in clinical trials, readers are advised to consult their provider about any questions.
11. What should consumers know if they are considering using magnets to treat pain?
It is important that people inform all their health care providers about any therapy they are using or considering, including magnetic therapy. This is to help ensure a safe and coordinated plan of care.
In the studies that did find benefits from magnetic therapy, many have shown those benefits very quickly. This suggests that if a magnet does work, it should not take very long for the user to start noticing the effect. Therefore, people may wish to purchase magnets with a 30-day return policy and return the product if they do not get satisfactory results within 1 to 2 weeks.
If people decide to use magnets and they experience side effects that concern them, they should stop using the magnets and contact their health care providers.
Consumers who are considering magnets, whether for pain or other conditions, can consult the free publications prepared by Federal Government agencies. See "For More Information."
If You Buy a Magnet…
Check on the company's reputation with consumer protection agencies.
Watch for high return fees. If you see them before purchase, ask that they be dropped and obtain written confirmation that they will be.
Pay by credit card if possible. This offers you more protection if there is a problem.
If you buy from sources (such as Web sites) that are not based in the United States, U.S. law can do little to protect you if you have a problem related to the purchase.
Sources: The FDA and the Pennsylvania Medical Society
12. Is the National Center for Complementary and Alternative Medicine (NCCAM) funding research on magnets for pain and other diseases and conditions?
Yes. For example, recent projects supported by NCCAM include:
Static magnets, for fibromyalgia pain and quality of life
Pulsed electromagnets, for migraine headache pain
Static magnets, for their effects on networks of blood vessels involved in healing
TMS, for Parkinson's disease
Electromagnets, for their effects on injured nerve and muscle cells
In addition, the papers by Alfano et al.,26 Swenson,21 and Wolsko et al.27 report on research funded by NCCAM.
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For More Information
NCCAM Clearinghouse
Toll-free in the U.S.: 1-888-644-6226
International: 301-519-3153
TTY (for deaf or hard-of-hearing callers): 1-866-464-3615
E-mail: info@nccam.nih.gov
Web site: nccam.nih.gov
Address: NCCAM Clearinghouse, P.O. Box 7923, Gaithersburg, MD 20898-7923
Fax: 1-866-464-3616
Fax-on-Demand service: 1-888-644-6226
CAM on PubMed
Web site: www.nlm.nih.gov/nccam/camonpubmed.html
CAM on PubMed, a database developed jointly by NCCAM and the National Library of Medicine, offers citations to (and in most cases, brief summaries of) articles on CAM in scientifically based, peer-reviewed journals. CAM on PubMed also links to many publisher Web sites, which may offer the full text of articles.
U.S. Food and Drug Administration (FDA)
Web site: www.fda.gov
Toll-free in the U.S.: 1-888-INFO-FDA (1-888-463-6332)
The FDA is a Federal agency responsible for protecting the public health by assuring the safety, efficacy, and security of medicines, biological products, medical devices, foods, cosmetics, and consumer products that produce radiation.
Center for Devices and Radiological Health (CDRH)
Web site: www.fda.gov/cdrh
Toll-free: 1-888-463-6332
The CDRH has consumer information on magnets and magnetic devices and on buying medical devices online.
Federal Trade Commission (FTC)
Web site: www.ftc.gov
Toll-free in the U.S.: 1-888-382-4357
The FTC is a Federal agency that works to maintain a competitive marketplace for both consumers and businesses. It regulates all advertising, except prescription drugs and medical devices, ensuring that advertisements are truthful and not misleading for consumers. Brochures include " 'Miracle' Health Claims: Add a Dose of Skepticism."
Definitions
Alloy: A metallic substance consisting of either a mixture of two or more metals, or a metal that has been mixed with a nonmetal.
Anecdotal evidence: Evidence made up of one or more anecdotes. In science, an anecdote is a story about a person's experience, told by that person.
Chiropractic: An alternative medical system that focuses on the relationship between bodily structure (primarily that of the spine) and function, and how that relationship affects the preservation and restoration of health. Chiropractors use a type of hands-on therapy called manipulation (or adjustment) as an integral treatment tool.
Clinical trial: A research study in which a treatment or therapy is tested in people to see whether it is safe and effective. Clinical trials are a key part of the process in finding out which treatments work, which do not, and why. Clinical trial results also contribute new knowledge about diseases and medical conditions.
Diabetic peripheral neuropathy: A nerve disorder caused by diabetes. This disorder leads to a partial or complete loss of feeling in the feet and, in some cases, the hands, and pain and weakness in the feet.
Efficacy: In scientific research, a treatment's efficacy is its power to obtain a desired effect, such as reducing pain.
ET: Electromagnetic therapy.
Fibromyalgia: A chronic disorder involving musculoskeletal pain, multiple tender points on the body, and fatigue.
General review: An analysis in which information from various studies is summarized and evaluated. Conclusions are then made based on this evidence.
Magnetic resonance imaging (MRI): A test that uses powerful magnets and radio waves to create detailed pictures of structures and organs inside the body.
Meta-analysis: A type of research review that uses statistical techniques to analyze results from a collection of individual studies.
Myofascial pain syndrome: A chronic musculoskeletal pain disorder. Pain may occur when "trigger points," or especially tender areas on the body, are touched, or in other points in the body.
Peer reviewed: Reviewed before publication by a group of experts in the same field.
Placebo: A placebo is designed to resemble as much as possible the treatment being studied in a clinical trial, except that the placebo is inactive. An example of a placebo is a pill containing sugar instead of the drug or other substance being studied. By giving one group of participants a placebo and the other group the active treatment, the researchers can compare how the two groups respond and get a truer picture of the active treatment's effects. In recent years, the definition of placebo has been expanded to include other things that could have an effect on the results of health care, such as how a patient and a health care provider interact and what the patient expects to happen from the care.
Plastic change: The ability of the brain's connections to change, which affects many functions such as learning and recovery from damage.
Prospective study: A type of research study in which participants are followed over time for the effect(s) of a health care treatment.
Pulsed ET: Pulsed electromagnetic therapy, in which the magnetic field created by an electric current is turned on and off very rapidly.
Randomized clinical trial (RCT): In a randomized clinical trial, each participant is assigned by chance (through a computer or a table of random numbers) to one of two groups. The investigational group receives the therapy, also called the active treatment. The control group receives either the standard treatment, if there is one, for their disease or condition, or a placebo.
Rare-earth element: One of a group of relatively scarce, metallic elements or minerals. Examples include lanthanum, neodymium, and ytterbium.
Rheumatologist: A physician (M.D. or D.O.) who specializes in inflammatory disorders of the joints, muscles, and fibrous tissues.
rMS: Repetitive magnetic stimulation. In rMS, an insulated coil is placed against a part of the body other than the head, and an electrical current generates a magnetic field into that area.
rTMS: Repetitive transcranial magnetic stimulation. This type of transcranial magnetic stimulation, or TMS (see definition below), is believed by some to produce longer lasting effects.
Sham: A sham device or procedure is one type of placebo (defined above). When the treatment under study is a procedure or device (not a drug or other substance), a sham procedure or device may be designed that resembles the active treatment but does not have any active treatment qualities.
Systematic review: A type of research review in which data from a set of studies on a particular question or topic are collected, analyzed, and critically reviewed.
TMS: Transcranial magnetic stimulation. In this type of electromagnetic therapy, an insulated coil is placed against the head, and an electrical current generates a magnetic field into the brain.
