The market for magnetic bracelets, knee pads and the like may now be worth about $1billion a year, but two American scientists argue in the journal on Friday that many people are being fooled as to their therapeutic benefits.
"Money spent on expensive and unproved magnet therapy might be better spent on evidence-based medicine," professors Leonard Finegold and Bruce Flamm wrote.
They said the many studies that purport to show magnets do work are suspect because a magnet's main characteristic - to be attracted or repelled by metals - would betray it compared with placebos.
But they said magnet wearers may feel better even if there is no supporting evidence.
"Perhaps subjects with magnetic bracelets subconsciously detected a tiny drag when the bracelets were near ferromagnetic surfaces (which are ubiquitous in modern life), and this distracted or otherwise influenced the perceived pain".
The pair warned the sophisticated marketing of magnetic devices could result in underlying medical conditions being left untreated.
"Magnets are touted by successful athletes, allowed to be widely advertised, and sold without restrictions, so it is not surprising that lay people think that claims of therapeutic efficacy are reasonable," they said.
Finegold is professor of physics at Drexel University in Pennsylvania and Flamm is a professor at Kaiser Permanente Medical Centre in California.
"Magnets are touted by successful athletes, allowed to be widely advertised, and sold without restrictions"
Professor of physics,
They said that even theoretically, magnet therapy appeared unrealistic given that human tissue does not appear to be affected when it is subject to the massive fields generated by magentic resonance imaging (MRI).
Finegold and Flamm said that if there were any healing effects of magnets they were apparently small since published research, both theoretical and experimental, weighed heavily against there being any therapeutic benefit.
"Patients should be advised that magnet therapy has no proved benefits," they said. "If they insist on using a magnetic device they could be advised to buy the cheapest - this will at least alleviate the pain in their wallet."