Experts are blaming a mixture of prescription and herbal medicines for a huge rise in deaths caused by adverse reactions to drugs. A senior member of the British Medical Association is now calling for a study into the effects of interaction between prescription and herbal medication.

Dr Andrew Dearden of the BMA's prescribing subcommittee is concerned over a fivefold increase in the number of people dying from drug side-effects. New figures from the Audit Commission reveal that the total over 10 years rose by 500 per cent, from just over 200 in 1990 to more than 1,000 in 2000.

Dr Dearden said yesterday that problems often stemmed from a misunderstanding of the term "medical". "People don't realise that, when a GP asks them, 'Are you taking any other drugs?', he or she means over-the-counter and herbal drugs as well as prescription medicines.

They think that because something has the word 'herbal' in front of it, it's not medication. They don't realise that what they are taking can interfere and interact with prescription drugs."

Last year alone, the Medicines Control Agency and the Committee on Safety of Medicines received 18,000 reports of suspected adverse drug effects, and even this figure is thought to be a vast underestimate of the situation.

"One problem is that society is becoming more and more drug oriented," said Dr Dearden, who expresses his concerns in April's Cosmopolitan Zest magazine. "Drug companies are marketing so many products now, and they have become increasingly used as relaxation and enjoyment agents. The problem is that prescription drugs are studied to determine their interaction, but herbal remedies don't have to go through this. A lot are unknown quantities in medical terms."

More than five million Britons now regularly use herbal medicines, to alleviate conditions as diverse as rheumatism, asthma, insomnia and depression.

A study at Exeter University, listed 108 cases of herb/drug interactions, and identified risks for individuals. Last week the European Commission took steps to ban up to 300 substances found in over-the-counter vitamin and mineral supplements.

Dr Dearden said herbal remedies could also be responsible for the dilution of medication. In the case of the Pill, this could result in unplanned pregnancies.

David Tredinnick MP, Treasurer of the Parliamentary Group for Complimentary and Integrated Health Care said: "We ought to be encouraging the use of alternative medicine, not restricting it. They should teach doctors about it, and bring it inside the NHS."