THE mystical draw of magnetic therapy has seen world leaders from Cleopatra to Bill Clinton convinced of its healing power.
But despite such longstanding popularity with the rich and powerful, new research has led to warnings from the United States that the "alternative" treatment has no proven benefits and simply targets vulnerable people looking for pain relief.
The report by American doctors concluded that the rapidly expanding commercial industry selling static magnet therapies is exploiting the people who buy and believe in the products.
Billions of pounds are spent annually on "static" magnetic bracelets, insoles, wrist and knee bands, back and neck braces, and even pillows and mattresses in the hope they will cure anything from back pain to migraines.
In Britain, Princes William and Harry have been seen wearing copper bracelets, which often have magnetic properties and have become something of a fashion statement.
The Silence of the Lambs actor Sir Anthony Hopkins is a known to be a believer in magnetic therapy, which dates from ancient times.
But Professor Leonard Finegold, of Drexel University in Philadelphia, who led the research said: "There is a billion-to-one chance that I am wrong. There is simply no evidence that this therapy works.
"These products cost huge amounts of money, and it would be just as effective to strap a fridge magnet to your wrist.
"Sometimes people feel pain relief if you tell them a bracelet has magnets in when it does not. It is a placebo effect. If people really must buy a magnet they should buy the cheapest as it will cause the least financial pain."
Magnetic bracelets are often pitched as a cure for pain from osteoarthritis, or as a means of warding off the condition. Last year, 2.8 billion was spent on magnets for pain relief.
A spokeswoman for the Arthritis Research Campaign said: "We are not yet sure whether pain relief is due to magnets or is merely a placebo effect. The trouble with marketing hype taking over from reality is that claims become unrealistic and irresponsible. People suffering from osteoarthritis are vulnerable, as they will try anything to stop the pain," she said.
"We would certainly recommend going to a GP before buying something expensive like a pillow or a mattress. Even bracelets can cost 30."
Magnetic therapy practitioners argue that there is a difference between the products sold commercially and those recommended by therapists.
Lilias Curtin, the lifestyle guru to Cherie Blair, became one of the first accredited magnet therapists in the country and began working from her spare bedroom at home.
She said: "I would refer these researchers to the 100 or so clinical trials that show magnet therapy reduces pain and acidity in the body.
"Magnet therapy can be phenomenal for joint pain by accelerating the healing in the area by neutralising it," Ms Curtin said. "It doesn't work for everybody. If it doesn't, people should go to a doctor.
"The majority of stuff sold over the counter is very weak indeed. Magnets by accredited therapists are up to four times stronger.
"I would always suggest people seek a qualified practitioner first before buying any item of magnet therapy. There are some brands that are so weak they could not have any effect."
Thousands of internet sites and mail-order firms offer magnets for almost every condition, and make claims to relieve skin conditions, pain and, in some cases, even cancer.
Ray Padfield-Krala, who owns and runs Magnetic, a British online company which sells magnetic jewellery, bed pads and even magnetic collars for dogs, cats and horses, said that almost 99 per cent of products on the market were not accredited and had little therapeutic value.
"People need to look for items that are certified by places like the British Complementary Medicine Association before spending too much money," he said.