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What are magnets?
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Is the use of magnets considered
conventional medicine or complementary and alternative medicine?
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What is the history of the discovery
and use of magnets to treat pain?
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How common is the use of magnets to
treat pain?
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What are some examples of theories and
beliefs about magnets and pain?
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How are static magnets used in
attempts to treat pain?
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How are electromagnets used in
attempts to treat pain?
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What is known from the scientific
evidence about the effectiveness of magnets in treating pain?
-
Are there scientific controversies
associated with using magnets for pain?
-
Have any side effects or
complications occurred from using magnets for pain?
-
What should consumers know if they
are considering using magnets to treat pain?
-
Is the National Center for Complementary
and Alternative Medicine (NCCAM) funding research on magnets for pain and
other diseases and conditions?
Introduction
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.
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Key Points
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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.
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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).
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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.
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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.
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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.
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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.
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Examples of Products Using Magnets
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Shoe insoles
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Heel inserts
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Mattress pads
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Bandages
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Belts
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Pillows and cushions
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Bracelets and other jewelry
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Headwear
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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.
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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.
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About CAM and Conventional Medicine
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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?"
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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.
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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.
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4. How common is the use of magnets to treat pain?
A 1999 survey of patients who had
, 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.
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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:
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Static magnets might change how cells function.
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Magnets might alter or restore the equilibrium (balance)
between cell death and growth.
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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.
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Weak pulsed electromagnets might affect how nerve cells
respond to pain.
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Pulsed electromagnets might change the brain's perception
of pain.
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Electromagnets might affect the production of white blood
cells involved in fighting infection and inflammation.
Here are two other theories and beliefs:
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Magnets might increase the temperature of the area of the
body being treated.
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"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.
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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.
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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
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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.
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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).
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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
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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.
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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
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The remaining review found no studies on magnets for neck
pain and stated that rigorous studies are much needed.21
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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.
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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
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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
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Some study authors suggested that a placebo effect could
have been responsible for the pain relief that occurred from magnets.22,30
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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.
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9. Are there scientific controversies associated with
using magnets for pain?
Yes, there are many controversies. Examples include:
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The mechanism(s) by which magnets might relieve pain have
not been conclusively identified or proven.
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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
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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.
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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
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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:
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Pregnant women, because the possible effects of magnets on
the fetus are not known.
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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.
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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.
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11. What should consumers know if they are considering
using magnets to treat pain?
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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.
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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.
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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.
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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."
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If You Buy a Magnet…
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Check on the company's reputation with consumer protection
agencies.
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Watch for high return fees. If you see them before
purchase, ask that they be dropped and obtain written confirmation that they
will be.
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Pay by credit card if possible. This offers you more
protection if there is a problem.
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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
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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:
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Static magnets, for fibromyalgia pain and quality of life
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Pulsed electromagnets, for migraine headache pain
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Static magnets, for their effects on networks of blood
vessels involved in healing
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TMS, for Parkinson's disease
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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
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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
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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.
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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.
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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."
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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.
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Trock DH. Electromagnetic fields and magnets:
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Basford JR. A historical perspective of the popular use of
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Pujol J, Pascual-Leone A, Dolz C, et al. The effect of
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Smania N, Corato E, Fiaschi A, et al. Therapeutic effects
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Hulme J, Robinson V, DeBie R, et al. Electromagnetic
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Swenson RS. Therapeutic modalities in the management of
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Carter R, Hall T, Aspy CB, et al. The effectiveness of
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Caselli MA, Clark N, Lazarus S, et al. Evaluation of
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American Podiatric Medical Association. 1997;87(1):11-16.
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Weintraub MI, Wolfe GI, Barohn RA, et al. Static magnetic
field therapy for symptomatic diabetic neuropathy: a randomized, double-blind,
placebo-controlled trial. Archives of Physical Medicine and Rehabilitation.
2003;84(5):736-746.
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Hinman MR, Ford J, Heyl H. Effects of static magnets on
chronic knee pain and physical function: a double-blind study. Alternative
Therapies in Health and Medicine. 2002;8(4):50-55.
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Alfano AP, Taylor AG, Foresman PA, et al. Static magnetic
fields for treatment of fibromyalgia: a randomized controlled trial. Journal
of Alternative and Complementary Medicine. 2001;7(1):53-64.
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Wolsko PM, Eisenberg DM, Simon LS, et al. Double-blind
placebo-controlled trial of static magnets for the treatment of osteoarthritis
of the knee: results of a pilot study. Alternative Therapies in Health and
Medicine. 2004;10(2):36-43.
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Segal NA, Toda Y, Huston J, et al. Two configurations of
static magnetic fields for treating rheumatoid arthritis of the knee: a
double-blind clinical trial. Archives of Physical Medicine and
Rehabilitation. 2001;82(10):1453-1460.
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Thuile C, Walzl M. Evaluation of electromagnetic fields in
the treatment of pain in patients with lumbar radiculopathy or the whiplash
syndrome. NeuroRehabilitation. 2002;17(1):63-67.
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Nicolakis P, Kollmitzer J, Crevenna R, et al. Pulsed
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sham-controlled trial. Wiener Klinische Wochenschrift.
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McLean MJ, Holcomb RR, Wamil AW, et al. Blockade of
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increase cell survival by inhibiting apoptosis via modulation of Ca2+ influx. The
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2001;37:215-220.
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Appendix I
Research on Theories and Beliefs On How Magnets Might
Relieve Pain
Theory: Static magnets might change how cells
function.
Description of Studies: (1) Mouse nerve cells were exposed to
static magnetic fields of three different strengths, and the cells were
stimulated with pulses of electricity. (2) Mouse nerve cells were exposed to a
static magnetic field and capsaicin (a pain-producing substance).
Findings: (1) Exposure of nerve cells in culture to a static
110-G magnetic field reduced their ability to transmit electrical impulses.
(2) Magnets prevented mouse nerve cells from responding to capsaicin.
Citations: (1) McLean et al., 199534
and (2) McLean et al., 200132
Theory: Magnets might alter/restore the balance
between cell death and growth.
Description of Study: Cultures of the U937 human lymphoma (a
tumor of lymph node tissue) cell line were exposed to a static magnetic field
at the same time that they were treated with agents that cause cell death.
Findings: Static magnet fields protected some cells from agents
that cause cell death and allowed them to survive and grow.
Citation: Fanelli et al., 199935
Theory: Static magnets might increase blood
flow.
Description of Study: Randomized clinical trial (RCT) of 20
healthy young men who wore static magnets or placebo devices on their forearms
for 30 minutes.
Findings: Blood flow was not significantly different when
comparing the results of the magnet session with the placebo session.
Citation: Martel et al., 200236
Theory: Weak pulsed electromagnets might affect
how nerve cells respond to pain.
Description of Study: The pain threshold to a hot surface was
measured for rats before and 30 and 60 minutes after exposure to weak pulsed
electromagnets for 30 minutes.
Findings: An increase in pain threshold (analgesic effect) was
found 30 and 60 minutes after exposure to pulsed electromagnets.
Citation: Ryczko and Persinger, 200237
Theory: Pulsed electromagnets might change the
brain's perception of pain.
Description of Study: Rats were exposed to pulsed
electromagnets (treatment group) or static magnetics (control group) 4
hours/day, for up to 28 days. The brains were removed and changes in the
number of serotonin (a brain chemical that affects stress and pain) receptors
were examined.
Findings: Significant increases in the number of receptors that
bind serotonin were observed in the brains of the rats exposed to a pulsed
electromagnet.
Citation: Johnson et al., 200338
Theory: Electromagnets might affect the
production of white blood cells involved in fighting infection and
inflammation.
Description of Study: Human and rat white blood cells were
exposed to electromagnets or pulsed electromagnets.
Findings: Both the human and rat cells exposed to either type of
electromagnetic therapy (ET) showed a modest increased capacity to multiply.
Citation: Johnson et al., 200139
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Appendix II
General and Systematic Reviews on CAM Magnetic Therapy for
Pain Published From August 1999 to August 2003
Static Magnetic Therapy
Authors: Ratterman et al., 20021
Type: General review
Description: Summarized 9 clinical trials on static magnetic
therapy for treating postpolio pain, diabetic peripheral
neuropathy, neck pain, low-back pain, fibromyalgia, postsurgical pain, and
headache.
Findings: The authors stated that static magnets may work for
certain conditions, but there is not adequate scientific support to justify
their use.
Electromagnetic Therapy
Authors: Hulme et al., 200319
Type: Systematic review
Description: Looked at 3 RCTs that compared pulsed
electromagnets (2 RCTs) or direct electric stimulation (1 RCT) with
placebo in treating osteoarthritis. Both trials of pulsed
electromagnets studied osteoarthritis of the knee; one of these studied
osteoarthritis of the neck as well. The primary measure of effectiveness was
pain relief.
Findings: The review found the RCTs to show that pulsed
electromagnets had a small-to-moderate effect on knee pain, and a much smaller
effect on neck pain. They concluded that "the current limited evidence does
not show a clinically important benefit" of pulsed electromagnets for treating
osteoarthritis of the knee or neck. They also identified a need for larger
trials to see whether clinically important benefits exist.
Authors: Huntley and Ernst, 200020
Type: Systematic review
Description: Reviewed 12 RCTs for 7 CAM modalities for pain and
other symptoms of multiple sclerosis. Included one RCT of rMS
(38 patients) and one RCT of pulsed electromagnets (30 patients). Other
modalities examined were nutritional therapy, massage, Feldenkrais bodywork,
reflexology, neural therapy, and psychological counseling.
Findings: Both magnet studies reviewed found short-term benefits
in relieving painful muscle spasms and other symptoms, and in improving
activity levels. Authors called for "rigorous research" on CAM for multiple
sclerosis patients.
Authors: Pridmore and Oberoi, 200014
Type: General review
Description: Discussed an array of basic and clinical research on TMS,
focusing on its effect on the central nervous system (CNS) and on its
potential effectiveness in relieving chronic pain.
Findings: Authors concluded, "Evidence indicates that TMS can
produce plastic changes in the CNS, which are observable at
both the cellular and psychological levels." Citing a lack of comprehensive
studies, they proposed that "studies are justified to determine whether TMS
can provide short-term or long-term relief in chronic pain."
Electromagnetic and Static Magnetic Therapies
Author: Swenson, 200321
Type: General review
Description: Searched for studies on various treatments for nonspecific
neck pain.
Findings: Found no studies on magnets for neck pain, despite the
popular interest in magnetic therapy, and "several very limited reports" from
use for other pain. The author stated that rigorous studies are "desperately
needed," especially those that could effectively double-blind patients and
practitioners to treatment.
Authors: Vallbona and Richards, 19999
Type: General review
Description: Pulsed Electromagnets--Commented on 32 RCTs
of pulsed electromagnets for conditions such as neck/shoulder pain, bone
and joint diseases, neurologic disorders, sleep disorders, wounds and ulcers,
postoperative bowel obstruction, and perineal trauma from childbirth. Pain
is a key symptom of many of the conditions examined, and pain intensity was a
clinical outcome measure in many of the studies. Static Magnets--Discussed
two RCTs: one for neck and shoulder pain and one for postpolio pain.
Findings: Pulsed Electromagnets--Authors found that 26 of
32 RCTs of pulsed ET showed it to be an effective
treatment for the conditions studied. Pain was decreased in disorders
including neck pain, osteoarthritis, and leg ulcers. Static Magnets--An
RCT of static magnets for neck and shoulder pain did not find any significant
pain relief in subjects using magnets. An RCT of static magnets for postpolio
pain yielded data that "suggest significant pain relief realized by patients
who were exposed to active magnets." Vallbona and Richards noted that many
studies of static magnets rely on anecdotal evidence
or small study sizes, are sponsored by magnet manufacturers, and/or are not
published in peer-reviewed journals.
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Appendix III
Reports on Randomized Clinical Trials of Magnetic Therapy
for Pain From January 1997 to March 2004
Static Magnetic Therapy
Authors: Wolsko et al., 200427
Description: Participants (26) with osteoarthritis
of the knee received either a sleeve containing magnets, to be worn over
the knee area, or a placebo sleeve that appeared identical. They wore their
sleeves for the first 4 hours and then at least 6 hours a day for 6 weeks.
Knee pain was measured at 4 hours, 1 week, and 6 weeks.
Findings: There was a statistically significant improvement in
pain in the treatment group at 4 hours, but not at 1 week or 6 weeks.
Authors: Winemiller et al., 20037
Description: Participants (95) who had had plantar
heel pain for at least 30 days received either shoe insoles containing a
magnet or insoles that were identical except for having no magnet. They wore
the insoles at least 4 hours a day 4 days/week for 8 weeks. Outcomes were
measured by a daily pain diary.
Findings: There were no significant differences in pain outcomes
between the two groups. Both experienced significant improvement in morning
foot pain and in enjoyment of their jobs (because of reduced foot pain).
Authors: Weintraub et al., 200324
Description: Patients (259) with diabetic peripheral
neuropathy wore static magnetic shoe insoles or an unmagnetized sham
device continuously for 4 months. Primary outcome measures were burning,
numbness and tingling, exercise-induced foot pain, and sleep interruption due
to pain.
Findings: Authors found that statistically significant reductions
in burning, numbness and tingling, and exercise-induced foot pain occurred in
the treatment group, but only during months 3 and 4. Some patients in the
treatment group with more severe baseline pain had significant reductions in
numbness and tingling and in foot pain throughout the study period.
Authors: Hinman et al., 200225
Description: Participants (43) with chronic knee pain
wore pads containing static magnets or placebos over their painful joints for
2 weeks. Outcomes were measured using self-administered ratings of pain and
physical function, and a timed 50-foot walk.
Findings: At the end of 2 weeks, those wearing magnets reported
significantly less pain, and better daily physical function and walking speed,
than those wearing placebos. Most of those wearing magnets experienced pain
relief within 30 minutes of the initial application of the magnets.
Authors: Carter et al., 200222
Description: Participants (30) with carpal tunnel
syndrome wore a magnetic or placebo device on the wrist over the carpal
tunnel area for 45 minutes. Participants rated their pain at 15-minute
intervals while wearing the device, after removing the device, and after 2
weeks.
Findings: The magnet was no more effective than the placebo in
relieving pain. Significant pain reduction was reported for both treatment and
placebo groups during a 45-minute application. The reduction in pain was still
detectable 2 weeks later; authors suggested that this could be from a placebo
effect.
Authors: Segal et al., 200128
Description: Patients (64) with rheumatoid arthritis
of the knee received one of two magnetic devices: one containing four
strong magnets or one containing only one weaker magnet. There was no
nonmagnetic or sham treatment. Devices were worn continuously for 1 week.
Outcome measures were the participants' pain diaries in which they assessed
their level of pain twice a day.
Findings: Both devices produced significant pain reduction after
1 week of use. A significant difference was not seen between the two groups.
The authors indicated that a nonmagnetic placebo treatment should be used in
future studies.
Authors: Alfano et al., 200126
Description: Patients with fibromyalgia (94
subjects) received either (1) usual care, (2) a pad containing static magnets
placed between the mattress and box springs, (3) an eggcrate-like foam
mattress pad containing static magnets of varying strength, or (4) a mattress
pad containing magnets that had been demagnetized. Outcome measures were
functional status, pain, and the number and intensity of tender points after 6
months.
Findings: Compared with the usual-care group and the sham group,
people who used the pads containing active magnets reported improvements in
function, pain intensity level, number of tender points, and intensity of
tender points after 6 months. However, except for pain intensity, measurements
were not significantly different from scores reported for the sham treatment
group or the usual-care group.
Authors: Collacott et al., 20008
Description: Participants (20) who had had chronic
low-back pain for at least 6 months wore a magnetic device for 1 week (6
hours/day, 3 days/week). After 1 week of no treatment, the participants wore a
sham device for 1 week (6 hours/day, 3 days/week). The primary outcome was
pain intensity, which was measured by a visual analog scale.
Findings: No significant differences in outcomes were found
between the magnetic and sham therapies.
Authors: Caselli et al., 199723
Description: Participants (34) with heel pain
wore a molded insole with or without a static magnetic foil insert for 4
weeks. The outcomes were measured in terms of the foot function index (pain,
disability, and activity restriction).
Findings: Use of the magnetic insole was no more effective than
the sham as measured by the foot function index. About 60% of patients from
both groups noted improvement in heel pain after 4 weeks, which suggests that
the molded insole itself was effective in treating heel pain.
Electromagnetic Therapy
Authors: Smania et al., 200318
Description: Participants (18) who had painful trigger
points from myofascial pain syndrome received, over
a period of 2 weeks, either 10 sessions of rMS or a sham treatment. During
each 20-minute treatment, two different coils from the rMS device delivered
pulsed ET when placed on each patient's trigger point. Patients were evaluated
for 1 month after the treatments, using pain scales and clinical exams.
Findings: The participants who received the magnetic therapy had
significant improvement in all pain measurements and in some range-of-motion
measurements that persisted throughout the evaluation period. The placebo
group did not show any significant improvement.
Authors: Nicolakis et al., 200230
Description: Participants (32) with osteoarthritis
of the knee lay on a pulsed electromagnetic mat or a sham mat for 30
minutes twice a day for 6 weeks. The primary outcome measures were pain,
stiffness, and physical function.
Findings: At the end of 6 weeks, physical function scores were
significantly improved for the treatment group compared with the sham group.
Pain and stiffness decreased for both groups, with what the study authors
called a "marked" placebo effect for participants using the sham treatment.
There was no significant difference between the groups for pain and stiffness.
Authors: Thuile and Walzl, 200229
Description: Two prospective
studies of ET for low-back pain (100
participants) and whiplash (92 participants). Half of the participants
in each study received ET twice a day for 2 weeks plus standard medications.
The other half received only standard medications. ET consisted of applying a
low-energy, low-frequency magnetic field cushion for 16 minutes and using a
whole-body mat for 8 minutes. Evaluation of the low-back pain participants
consisted of counting the interval to reported pain relief and/or painless
walking, and measuring hip flexion to the point of pain. Participants in the
whiplash study reported their pain on a 10-point scale and had their range of
motion measured.
Findings: In the low-back pain study, the ET group reported the
following compared with the control group: statistically significant pain
relief and/or pain-free walking 3.5 days sooner and increased ability to bend
at the hip. In the whiplash study, the ET group, compared with the control
group, had significantly decreased pain in the head, neck, and shoulder/arm
areas after treatment, and significantly greater range of motion.
Authors: Pipitone and Scott, 200111
Description: Patients (69) with osteoarthritis of
the knee used a pulsed electromagnet or a sham device for 6 weeks. Devices
were placed on or between the knees for 10 minutes three times a day. The
primary outcome measure was a reduction in pain.
Findings: Pulsed ET significantly reduced pain, measured by
several scales, over a 6-week period in the treatment group, and did not
produce any adverse effects. No improvements were noted with the
placebo-treated group. The authors suggested further studies of pulsed ET for
osteoarthritis and other conditions.
Authors: Jacobson et al., 200110
Description: Participants (176) with osteoarthritis
of the knee were treated with ET for a total of 48 minutes per treatment
session for eight sessions during a 2-week period or sat near the
electromagnet with the magnet off (placebo). Participants used a subjective
10-point scale to rate their pain level before and after each treatment and 2
weeks after the final treatment. Patients also kept a diary of pain intensity
before, during, and 2 weeks after the trials, in which they recorded entries
daily upon waking and before going to sleep. They did not take any medicines
or use topical analgesics.
Findings: ET significantly reduced pain after a treatment session
in the magnet-on (treatment) group (46% reduction) compared to the magnet-off
(placebo) group (8%).
Authors: Pujol et al., 199817
Description: Patients (30) with localized injury
to the musculoskeletal system received 40 minutes of either rMS
treatment or sham treatment. Stimulation intensity was adjusted in each
patient to avoid excessive discomfort. Outcome measure was a 101-point pain
rating scale.
Findings: After one treatment, the pain score decreased
significantly in rMS-treated patients compared with sham-treated patients (59%
versus 14% reduction). The effect persisted for several days.
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NCCAM Publication No.
D208
May 2004
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