Using herbal supplements before undergoing surgery may interfere with anesthesia or put patients at risk for complications such as increased bleeding. Patients would do well to lay off the herbs before going under the knife.

There is an unspoken 'don't ask, don't tell' policy in most doctors' offices, where physicians don't ask and patients rarely tell about their herbs or dietary supplements.

The patient's silence could be deadly, since many herbs can increase bleeding time during and after surgery, cause changes in blood pressure and prolong the effects of anesthesia.

Because people may not regard herbs as medication, they may be unaware herbal supplements can carry side-effects.

Some supplements that can interfere with bleeding time during surgery include ginkgo, feverfew, ginger and vitamin E.

In addition, ginseng may trigger high blood pressure, while garlic supplements may lower blood pressure. Herbs that can intensify or prolong anesthesia include St. John' s wort and kava kava.

All herbal supplements be stopped two weeks prior to elective surgery, no matter how minor.

Annual Meeting of the American Academy of Cosmetic Surgery, San Diego, February 23, 2001