POPULAR herbal medicines, including ginkgo, ginseng and garlic, can cause serious complications during surgery, a study has found.

Despite their reputation as "mild" or "natural" remedies, many herbs can cause bleeding, heart problems and low blood sugar. Others can react dangerously with pharmaceutical drugs and suppress immunity.

Scientists at the University of Chicago said doctors should ask patients about herbal medicines before surgery.

The team, led by Dr Michael Ang-Lee, studied the effects of eight remedies: echinacea, ephedra, garlic, ginkgo, ginseng, kava, St John's wort and valerian. Their results were published in the Journal of the American Medical Association.

Up to a third of pre-surgical patients take herbal medicines, but many do not tell their doctors. The researchers found that little information was available about their effects on surgery.

But garlic, ginkgo and ginseng increase the risks of bleeding; ephedra causes heart beat irregularities; and ginseng triggers low blood sugar. Kava and valerian, which are both sedatives, can increase the effects of anaesthetics, while St John's wort increases the metabolism of drugs used before and after operations.

Echinacea, which is taken to boost the immune system, can cause immune suppression and could interfere with wound healing.

From Healthy.net