Aug 9 2011 --- Many people use herbal medicines believing them to be safe simply because they are 'natural'. However many of these products have potentially dangerous interactions with other drugs and can have similar side effects to conventional drugs. New research published in BioMed Central's open access journal BMC Medicine reveals that many over-the-counter herbal products do not contain any of the key information required for safe use.

Despite their wholesome image, many herbal products have adverse effects and a third of users are completely unaware of any risks. Researchers from the University of Leeds bought 68 different preparations of five commonly used remedies (St John's wort, Asian ginseng, Echinacea, garlic and Ginkgo) at two well known health food stores, three large chain pharmacies, and three pharmacies at supermarkets. The information provided with these products was compared to safety information, provided by the US National Center for Complementary and Alternative Medicine, and was evaluated for completeness and accuracy regarding precautions, interactions with other drugs, and side effects.

All of the products chosen are known to have potentially harmful effects for some people. St John's wort can reduce the effectiveness of the contraceptive pill. It can also affect warfarin, which is taken to prevent blood clotting. Asian ginseng is not suitable for people with diabetes and Ginkgo and Echinacea can cause allergic reactions. Even garlic can cause problems for some people because it can thin the blood and interfere with drugs used to treat HIV. The researchers found that 93% of the products evaluated were unlicensed, and consequently not required to meet any standard of safety or quality, and over half of these were marketed as food supplements. Only 13% contained an information sheet and only three contained an acceptable amount of safety information.

Prof Theo Raynor said, "Consumers need reliable and comprehensive information when buying herbal remedies – information which tells them whether the remedy is suitable for them. From April 2011 an EU directive requires herbal medicinal products to be licensed, or to get Traditional Herbal Registration (THR), which means the information with the product has been approved. This applies to things like St John's wort and Echinacea, but not necessarily to others such as Asian ginseng and ginkgo. It also does not apply to existing stock, which can still be sold off. People should look out for the 'THR logo' when buying these products. Furthermore pharmacists and doctors need to be made aware what herbal remedies people are taking so that their patients receive the best possible care."