Scores of traditional Chinese medicine stores in Britain's high streets are being investigated for selling illegal medicines, the BBC has learned.
Traditional medicines have been used for centuries
Radio Five Live has discovered that 67 outlets selling Chinese medicines are under suspicion.
It is estimated that 6,000 stores across the country offer treatment for conditions ranging from eczema to the menopause.
But the industry, although growing in popularity, is largely unregulated.
At the Herb Garden store in Leigh on Sea, Essex, an undercover reporter from the Five Live Report was two weeks ago sold a herbal slimming pill and told it contained rhubarb and honeysuckle.
Tests showed it contained fenfluarmine - an illegal pharmaceutical considered to be so dangerous that it is banned in most countries worldwide, including the UK.
The owner of the store, Anna Yang, was prosecuted earlier this year for illegally selling the same drug.
She was fined £30,000 with another £20,000 in court costs.
The maximum sentence for selling an illegal medicine is two years imprisonment.
The BBC reporter was also sold two other prescription-only drugs - Danthron - a specialist laxative which has cancer causing properties and is only recommended for use with terminally ill patients, and Sibutramine - prescribed in cases of extreme obesity.
Ms Yang said that she was concerned about the BBC's allegations.
She said she was reliant on assurances from suppliers as to the contents of the products and had been in touch with the Medicines and Healthcare Products Regulatory Agency.
She added that the products had now been withdrawn from sale.
Danny Lee-Frost, head of enforcement at the MHRA, said: "There are huge amounts of money to be made in this area.
"The main motivation is money."
He said unscrupulous traders were putting patient's lives at risk.
The BBC has learned that several practitioners are currently facing prosecution, and another 63 stores are being investigated.
David Woods visited Ms Yang in 2000 for acupuncture on his painful knees.
He said: "She said I should lose a bit of weight and it would help my knees.
"She said she had these new pills, really good pills and would I like some? So I said yes.
"It ended up to be the equivalent of a class A drug."
Since taking fenfluarmine David Woods has had a permanently damaged heart.
"My heart used to slow down and speed up. I honestly thought I was dying. I have nothing to thank her for. Nothing."
Dr Karl Metcalfe, a consultant physician at Southend hospital said he has treated nine of Anna Yang's former patients but fears there may be more as some people may not have reported symptoms to their GPs.
"For a medically qualified person to be issuing these drugs would be reprehensible.
"For a non medically qualified person to be doing it is well very alarming and quite clearly criminal."
In a separate case, Sandi Stay, of Hove, had to have both her kidneys removed after taking Aristochlia, a cancer causing herb which is banned across the UK.
Mrs Stay said she went to a Chinese medicine store and was given the herb to treat her psoriasis.
In her case the store which she claims sold her the drug was found not guilty because the jury accepted the store had taken measures to ensure its medicines did not contain Aristochlia.
Dr Mark Thursz, a consultant physician at St Mary's Hospital in Paddington said he had seen a huge rise in the number of patients being referred to him with liver failure or hepatitis after taking Chinese herbal medicine.
He said: "Many people believe herbal remedies are safe, but they should be seen in the light as conventional remedies in that they can adverse reactions.
"When you get a box of pills you get a long list of potential side effects.
"You don't get that with herbal remedies because practitioners try to make you believe they are safe."
Under current regulations Chinese medics are treated as shop keepers rather than traders, so in the same way a butcher prosecuted for selling bad meat would be allowed to continue trading so are they.
Dr Jidong Wu, of the Association of Traditional Chinese medicine is calling for tighter regulation.
He said "dodgy and fake" practitioners were damaging the image of Chinese medicine.