According to scientific experts magnet therapy has no proven benefits, and they suggest money would be better spent on evidence based medicine.
They say that any healing effect is likely to be insignificant.
Magnetic devices which are very expensive, claim to have therapeutic qualities.
They come as magnetic bracelets, insoles, wrist and knee bands, back and neck braces, and even pillows and mattresses.
It is estimated that sales reach over a billion dollars globally each year.
But Professors Leonard Finegold and Bruce Flamm say that many studies of magnet therapy are flawed because it is difficult to blind subjects to the presence of a magnet.
Finegold and Flamm warn that self treatment with magnets may result in an underlying medical condition being left untreated.
They are not surprised that people believe the healing claims espoused, as they are widely advertised, and sold without restrictions, and are also promoted by successful athletes.
However they say even in theory magnet therapy is unrealistic.
They suggest extraordinary claims demand extraordinary evidence, and potential patients should be advised that magnet therapy has no proven benefits.
They advise if a patient insists on using a magnetic device they should buy the cheapest as this will at least ease the pain in their wallet.
The study is published in the British Medical Journal.