BEIJING -- China has been carrying out research into the side-effects and toxicity of traditional Chinese medicine (TCM) to ensure that people can use centuries-old pharmaceuticals safely, said insiders on Wednesday.

The belief that all TCM remedies are non-toxic and harmless to health is a common misconception, said She Jing, head of the State Administration of Traditional Chinese Medicine.

The Chinese Pharmacopoeia, published in 2000, listed 72 kinds of TCM substances that are toxic in nature, she said.

TCM doctors in ancient times knew that some TCM substances were toxic, but the key was to adjust herb prescriptions in specific cases, said Du Guiyou, a researcher at the China Academy of Traditional Chinese Medicine.

"Responsible TCM doctors adjust prescriptions according to the patient's condition. They do not apply the same prescription to every patient," said Du.

"Patients taking TCM without diagnosis or without a doctor's prescription are asking for trouble," he said.

According to She, the administration has established three TCM toxicity evaluation centers and four TCM clinical testing centers. Expert teams have also been set up to carry out laboratory tests and research toxic compounds used in TCM.

Five years ago, Du and his 24 fellow researchers were given 1 million yuan (125,000 U.S. dollars) to discover whether aristolochic acid contained in some TCM compounds could cause kidney damage, sometimes referred to overseas as "Chinese herbs nephropathy".

The team's conclusion was that the ancient prescription of Longdan xiegan wan, a well-known and widely used TCM for liver problems, was not problematic. However, in the 1830s, some doctors changed the prescription by adding a herb called Caulis aristolochia manshuriensis (Chinese name guan mu tong) when making the remedy. Caulis aristolochia manshuriensis contains the toxicant aristolochic acid.

In 2003 the State Food and Drug Administration banned the use of guan mu tong in making Longdan xiegan wan after some cases of kidney problems - such as uremia - were reported after taking the drug.

The administration then required pharmaceutical companies to replace guan mu tong with mu tong, another kind of herb which does not cause the same problems.

TCM has been used in China for hundreds of years. Research must continue so that, with better understanding, adverse reactions and side-effects or even toxicity can be detected and further regulations made, said Du.

"This kind of research is very important in preserving TCM and making it serve the people. We need more of it," he said.

The country's adverse reaction reporting system also needs to be further improved, he added.