Most doctors will advise patients to stop taking any herbal remedy at least 1 week prior to undergoing surgery. That’s because many herbal supplements can cause problems during and after an operation and may even delay the healing process. Here are some herbs that are especially problematic:

Echinacea. This herb can exacerbate the inflammation process and may interfere with prescribed immune-suppressing medications.

Garlic, Ginger, Ginkgo & Ginseng. All of these herbal products can increase the risk of bleeding and the effect of anticlotting drugs. Ginseng can also raise blood pressure.

Goldenseal & Licorice. Both of these herbs tend to increase swelling (edema) and may raise blood pressure.

Kava & Valerian. These herbs can prolong the sedative
effects of certain anesthetics used during surgery.

St. John’s Wort. This herb interferes with other medications, such as steroids, anticlotting agents and immune-suppressing drugs. It can also prolong the sedative effects of certain anesthetics used during surgery.

Source: July 2007 Consumer Reports on Health.