PRESS ASSOCIATION -- Some herbal remedies are lacking clear safety information on possible side effects, researchers have said.
Earlier this year, new EU rules said many herbal products should carry warnings on side effects and interactions with prescription medicines.
But new research has shown that even products that fall under these new rules are available online and in shops without the safety information and old stock is still on sale.
Experts are now warning people to look out for a "THR" logo on products, showing they have traditional herbal registration.
The study looked for information on precautions (such as Asian ginseng not being suitable for people with diabetes), interactions with conventional medicines (such as St John's Wort, not to be used with the contraceptive pill and warfarin) and any side effects (such as ginkgo leading to possible allergic reactions).
Overall, 51 (75%) of 68 products examined contained none of the key safety messages. Many products were unlicensed, meaning they fell outside of rules saying they should carry warnings.
Professor of pharmacy Theo Raynor, who led the University of Leeds study published in the journal BMC Medicine, said: "The best advice to consumers is buyer beware, as it always has been. Many people believe herbal medicines are somehow different to other medicines because they are 'natural'.
"However, any substance that affects the body - no matter where it came from - has the potential to do harm if it is not taken correctly. Consumers need reliable and comprehensive information when buying herbal medicines - information which tells them whether it is suitable for them.
"I would advise anyone buying a herbal medicine to check that the box or packaging contains the THR logo, which shows that the information it comes with has been approved. Herbal medicines should, ideally, be purchased where trained staff are available so that consumers can have any questions answered.
"This information should be available from pharmacists. People should also always tell their doctor about herbal medicines they are taking so they receive the best possible care."