JOIN USCommonly used remedies like St John's wort, Asian ginseng, Echinacea, garlic and Ginkgo are as strong as their allopathic counterparts. Many of them do not list key information required for safe use, reports the journal BMC Medicine.
For instance, St John's wort can reduce effectiveness of contraceptive pills. It can also affect warfarin, a drug prescribed for blood clotting.
Asian ginseng is not suitable for diabetics, while Ginkgo and Echinacea can cause allergic reactions. Even garlic can cause problems for some people because it can make the blood thinner and interfere with drugs used to treat HIV.
Theo Raynor, from the University of Leeds, who led the study, said: "Consumers need reliable and comprehensive information when buying herbal remedies."
Leeds researchers bought 68 different formulations of these medicines from two well- known health food stores, three large chain pharmacies and from supermarkets.
They found that 93 percent of these products were unlicensed, hence not required to meet any standard of safety or quality, and over half of these were marketed as food supplements.
Only 13 percent contained an information sheet and only three contained an acceptable amount of safety information.