Physicians need to specifically ask patients about herbal medication use

Professor Jonathan Moss

And scientists have found some preparations have an impact if taken up to a week before a patient goes under the knife.

Among the popular herbs studied were echinacea, gingko biloba, garlic, St John's wort and valerian - all widely-available in tablet form.

The researchers, from the University of Chicago, have published guidelines on when patients should stop taking herbal medicines in the influential Journal of the American Medical Association.

They hope that their work will encourage doctors to discuss the potential dangers with patients.

Researcher Dr Chun-Su Yuan said: "While most of these substances appear to be safe for healthy people, for surgical patients they can affect sedation, pain control, bleeding, heart function, metabolism, immunity and recovery in ways that we are just beginning to understand."

Popular medications

Studies suggest that as many as one third of pre-surgical patients take herbal medications.

However, many of those patients fail to disclose herbal use during pre-operative assessment, even when prompted.

Further, doctors often are unsure what to do with the information.

Professor Jonathan Moss, who also worked on the research, said: "Physicians need to specifically ask patients about herbal medication use.

"Many patients think of herbal medications not as supplements but as drugs.

"Other patients may not want to admit to their use to physicians.

"But in order to optimise patient safety and pain control during and after surgery, we need to know what herbal as well as over-the-counter or prescription drugs each patient takes."

Current guidance

The American Society of Anesthesiologists has recognised the potential for adverse reactions and suggests that patients stop taking all herbal medications two weeks before surgery.

This advice may be difficult to implement, however, since most preoperative evaluations occur only a few days prior to surgery.

So the Chicago researchers began to search for more targeted recommendations.

They focused on the eight most common herbs - echinacea, ephedra, garlic, gingko biloba, ginseng, kava, St. John's wort, and valerian - which account for 50% of all single-herb preparations sold.

They warn that the ingredients of herbal medications vary enormously from maker to maker, that potency and purity are inconsistent, and that product labels are not always accurate.

But they believe the guidelines are useful as many doctors remain unaware of the potential risk.

More than 5,000 suspected herb-related adverse reactions were reported to the World Health Organisation before 1996, said the researchers.

Between 1993 and 1998 a total of 2,621 adverse reactions, including 101 deaths, were reported to the United States Food and Drug Administration.

	Echinacea
	Relevant effects:				Boosts immunity.
	Concern during surgery:				Allergic reactions, impairs immune suppressive drugs, could impair wound healing.
	Recommendations:				Discontinue as far in advance as possible.
	Ephedra
	Relevant effects:				Increases heart rate & blood pressure.
	Concern during surgery:				Risk of heart attack, stroke, interaction with other drugs, kidney stones.
	Recommendations:				Discontinue at least 24 hours before surgery.
	Garlic
	Relevant effects:				Prevents clotting.
	Concern during surgery:				Risk of bleeding.
	Recommendations:				Discontinue at least 7 days before surgery.
	Ginko
	Relevant effects:				Prevents clotting.
	Concern during surgery:				Risk of bleeding.
	Recommendations:				Discontinue at least 36 hours before surgery.
	Ginseng
	Relevant effects:				Lowers blood glucose, inhibits clotting.
	Concern during surgery:				Increases risk of bleeding. Interferes with anti-clotting drug.
	Recommendations:				Discontinue at least 7 days before surgery.
	Kava
	Relevant effects:				Sedates, decreases anxiety.
	Concern during surgery:				May increase sedative effects of anesthesia.
	Recommendations:				Discontinue at least 24 hours before surgery.
	St. John's wort
	Relevant effects:				Acts like anti-depressants such as Prozac.
	Concern during surgery:				Alters metabolisms of other drugs.
	Recommendations:				Discontinue at least 5 days before surgery.
	Valerian
	Relevant effects:				Sedates.
	Concern during surgery:				Long-term use could increase the amount of anesthesia needed.
	Recommendations:				Taper dose weeks before surgery.