Science Daily, April 21, 2004
We usually think of magnets as something we put on the fridge to hold up a favorite cartoon. But magnets have been used for centuries to treat pain, and a survey found that many Americans with arthritis or fibromyalgia have used magnetic bracelets for pain relief, even though magnet therapy has not been well studied. Now, a British study suggests that magnetic bracelets may provide pain relief in people with arthritis in their knee or hip. “We are clear that there is a significant reduction in pain with magnetic bracelets.” says lead researcher Tim Harlow, a family physician at College Surgery in Devon. “What we cannot say with certainty is if it is due to a placebo effect, an effect of the magnet or a mixture of the two.”
This study, published in the British Medical Journal (BMJ), joins a growing group of studies on magnetic therapy and chronic pain, which have had mixed results. Dr. Harlow and his colleagues looked at 194 people with osteoarthritis in their hip or knee over a 12-week period. Participants were divided into three groups. One group received a standard-strength magnetic bracelet, which has a strength of 170 to 200 mTesla, one group wore a weaker bracelet, with a strength of 21 to 20 mTesla, and the third group wore a dummy bracelet with no magnet.
There are two types of magnets used in health, static magnets and electromagnets. The BMJ researchers used a static magnet, which has an unchanging magnetic field, rather than an electromagnet, which generates magnetic fields only when an electrical current runs through it. There are also two ways to wear a magnet for pain relief: directly over the affected area for a certain period of time each day, or on the wrist as a bracelet, so it affects the whole body. The researchers chose to have participants wear a magnetic bracelet for the 12-week period.
To evaluate the magnets, the researchers used a set of standard questions designed to assess pain, disability and joint stiffness in people with osteoarthritis. In the standard bracelet group, they found that the score from this questionnaire dropped from 10.7 to 7.8, compared to 10.0 to 9.3 in the dummy group. Unfortunately, the weak-bracelet group accidentally contained some bracelets with strong magnets, so the researchers were not able to determine whether there was a significant difference between the strong and weak magnets. Another issue that arose was that it was easy for participants with non-magnetic bracelets to realize that they were in the placebo group because their bracelets had no magnetic qualities.
Still, the researchers wrote that the pain reduction associated with the standard magnet bracelets was similar to that seen in studies of conventional osteoarthritis treatments, including non-steroidal anti-inflammatory drugs, such as Tylenol and ibuprofen, and exercise therapy. Additionally, the magnets appear to be free of side effects, unlike pain relievers, which are associated with gastrointestinal problems and, for certain drugs, heart attacks and strokes.
But while researchers understand how anti-inflammatory drugs and exercise therapy work, they only have theories when it comes to magnet therapy. According to a report from the National Center for Complementary and Alternative Medicine, some think that static magnets increase the flow of blood because it contains iron. As a result, more oxygen and nutrients reach the body’s tissues. Others suggest that magnets affect cell function, or change the balance between cell growth and death. In fact, electromagnetic fields but not static magnetic fields have been thought to increase cancer risk.
Neil Segal, MD, an assistant professor of orthopedics and rehabilitation at the University of Iowa, says it is critical that studies determine how magnets relieve pain. Dr. Segal has studied static magnets in people with rheumatoid arthritis of the knee. He compared strong and weak magnets in 64 participants, and found that both devices, which were placed on the knee, reduced pain after one week.
Dr. Harlow says that future studies should look at magnets of different strengths for longer periods of time in people with different kinds of pain. In the meantime, he cautions that people considering magnets for pain relief should talk to their doctors about it. Certain people, such pregnant women, people with a medical device such as a pacemaker or insulin pump, and people who wear a medication patch should not use static magnets.
“Magnets are appealing because osteoarthritis is a chronic condition for which our treatments are unsatisfactory.” Dr. Harlow says, “On the strength of the evidence, I am prepared to recommend static magnets to people with osteoarthritis.”
Dr. Segal is a bit more cautious about magnet therapy. “When I talk to patients I tell them that we don’t have evidence to definitively say whether certain magnets work, or how they work if they do.” he says. “Alternatively, I’m not aware that static magnetic devices have harmed anyone.”
For those who are interested in buying magnets designed for pain relief, the Food and Drug Administration (FDA) suggests checking the company’ reputation with consumer protection agencies and watching out for high return fees. The FDA also advocates buying magnets magnetic bracelets cost about $20 from US-based companies, which US law has more control over.