Medical experts have warned patients that they should not place "false hope" in promises made by untested internet miracle cures.
"Surreptitious promotion and misleading stories" online are duping many vulnerable patients into parting with their money, according to independent medical charity Sense About Science.
Tracey Brown, the charity's managing director, said: "We've been contacted by so many people exhausted from the pressure they feel to try advertised treatments, dietary regimes and exercises.
"One person told us how the last years of his wife's life were spent endlessly pursuing new treatments, from goats blood serums to unlicensed stem cell treatments abroad, all to no avail."
The Royal College of GPs has given its backing to a new guide published by the charity that explains how to tell the beneficial drugs from the bogus.
Vice chairman Dr Clare Gerada said the guide, called I've Got Nothing to Lose by Trying It, provides "a wealth of sensible information" to patients and the public.
"It goes a long way to taking the mystery out of medicine and I would recommend it to patients as a common-sense read," she said.
Patients particularly targeted by bogus claims include those suffering from Parkinson's disease, multiple sclerosis and motor neurone disease.
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