Over-the-counter 'natural' weight-reducing products can cause harm and may even kill, Hong Kong study warns

The study is published in the British Journal of Clinical Pharmacology.

The researchers looked at the ingredients in the 81 slimming products that these people had taken. They found 12 different agents that fell into five categories: undeclared weight-loss drugs; drug analogues (unlicensed chemical derivatives of licensed drugs); banned drugs; drugs used for an inappropriate indication; and thyroid hormones.

"People like the idea of using a natural remedy because they think that if it is natural, it will be safe. There are two problems here. Firstly not all natural agents are harmless, and secondly the remedies also contain potentially harmful manufactured drugs," says Dr Magdalene Tang, who works at the Toxicology Reference Laboratory at the Princess Margaret Hospital in Hong Kong.

She believes that fewer people would use these products if they were more aware of the potential risks involved.

While the research concentrated on cases in Hong Kong, the work raises worldwide concerns. These slimming products are widely available over the counter not only in Hong Kong, but in other countries where drug regulation is relatively non-comprehensive. In addition, anyone can buy them over the internet even if you do live in regions with tighter regulatory control.

"The only way to tackle this is if people stop buying these products, and governments take prompt, appropriate law-making and surveillance actions," says Dr Tang.

Dr Tang is particularly keen that doctors ask patients about their use of over the counter slimming products if they come into a clinic with strange symptoms. "The active participation of front line medical staff together with toxicology laboratories is a crucial element in the long-term effort to eradicate this problem," says Dr Tang.