Herbal supplements have become big business in recent years, with estimated US sales of more $3 billion in 1999. Surveys have found that up to 60 percent of people - women more so than men - use herbal products. In one such survey in Minnesota, the herbs most commonly used were ginseng, echinacea, garlic, ginkgo, St. John's wort, ginger, ephedra, and goldenseal.

While the health benefit claims of various herbs remain controversial, a new study has warned of their use in people undergoing surgery. That report identified a number of herbal medications that can have a negative impact during surgery (see Table). The researchers recommended how long before an operation to stop taking the supplement, based on the time it takes the body to fully eliminate each compound.

Herb	Potential adverse effect	When to stop taking before surgery
Garlic	Bleeding	7 days
Ginkgo	Interferes with clotting, can lead to possible excess bleeding	36 hours
Ginseng	Inhibits a blood-thinning drug used during surgery Hypoglycemia	7 days
Ephedra	Cardiovascular instability	24 hours
Kava	Increased sedative effects of anesthetics	24 hours
Valerian	Increased sedative effects of anesthetics	Weeks - taper off gradually; sudden stopping can cause withdrawal problems
St. John's wort	Increased metabolism of many drugs used in perioperative period	5 days

Surveys have found that many people who take herbal products do not tell their doctors about them. If you are taking any supplements - these or others - be sure your doctor knows about it.

Related information: Nutrition - basics