Quality survey Health benefits Safety Reading labels Ask the supplier Standards & regulations


Testing news
Ask the expert
Contact us
Privacy policy

Headline News

Supplements and Surgery -- What to Tell Your Doctors
21 September 2001
by Wyn Snow, Managing Editor

Anyone facing surgery wonders, "What if something goes wrong?" Patients know to tell their doctors what medications they take; also, doctors and nurses routinely ask for information about prescription and over-the-counter drugs during the preparatory stages before surgery. But what about botanicals and other kinds of dietary supplements? Can they affect surgery and anesthesia?

The short answer is yes, some can.

A recent article in the Journal of the American Medical Association (JAMA) listed eight herbs that might affect surgery or anesthesia and recommended that doctors ask their patients what supplements they are taking. Similarly, the American Society of Anesthesiologists (ASA) has published a pamphlet listing common uses and potential side effects of thirteen herbs.

SupplementQuality.com investigated further to learn not only which supplements can affect surgery and anesthesia -- but why and how.

Other supplements and surgery

A few non-herbal supplements -- such as vitamins, minerals, and other special purpose supplements -- also have the potential of affecting surgery and anesthesia. SupplementQuality.com asked Paul Thomas, registered dietitian (RD) and editor/publisher of The Dietary Supplement newsletter, which non-botanical supplements people should be careful about before surgery.

According to Thomas, "Vitamin E is a blood thinner, but nothing else immediately comes to mind. It's possible one should stop taking antioxidants during chemotherapy or radiation treatment for cancer -- but as to how soon afterwards one can resume, or whether one should take antioxidants afterwards to protect healthy cells, unfortunately none of these questions have answers. There are differences of opinion, but these are based on guesswork and speculation and little else."

Two books that begin to address the question of surgery risks and potential interactions between supplements and drugs are: Physician's Desk Reference for Nutritional Supplements, and Allison Sarubin's The Health Professional's Guide to Popular Dietary Supplements.

Which herbs are especially important?

The following list shows the specific herbs and potential side effects named in the JAMA article and ASA pamphlet.

None of these possible side effects have been proven scientifically beyond a shadow of a doubt -- what the federal Food and Drug Administration (FDA) would call significant scientific agreement. Both the JAMA article and ASA pamphlet used phrases like may cause, may interact with, may prolong throughout. However, some degree of suggestive evidence does exist linking these herbs and potential side effects.

Herb JAMA article: potential side effect risks ASA pamphlet: potential side effect risks
Echinacea immune suppression (could interfere with wound healing) liver inflammation in combination with certain drugs
(ma huang)
heartbeat irregularities blood pressure and/or heart rate
Feverfew   bleeding
Garlic bleeding bleeding
Ginger   bleeding
Ginkgo biloba bleeding bleeding
Ginseng bleeding; low blood sugar blood pressure and/or heart rate; interaction with anticlotting medications
Goldenseal   high blood pressure; swelling
Kava increase anesthesia effects increase antiseizure medication and/or anesthesia effects
Licorice   high blood pressure; swelling; electrolyte imbalances
Saw palmetto   interact with other hormone therapies
St. John's wort increase metabolism of drugs used before and after operations prolong anesthesia effects
Valerian increase anesthesia effects increase antiseizure medication effects or prolong anesthesia effects

Do herbalists agree?

SupplementQuality.com contacted several leading herbalists and asked them if this list and description of potential side effects is accurate.

Roy Upton, Executive Director of the American Herbal Pharmacopeia, agrees that the list is basically correct -- with two exceptions. Upton says, "I believe the warning about St. John's wort and anesthesia was an anomaly. I'm not sure what the problem is with echinacea and wound healing. Wound healing is one of its confirmed effects due to its action as a hyaluronidase inhibitor. Also, many botanicals affect metabolization of drugs. One of the most powerful is grapefruit juice."

Herbalist Jonathan Treasure spoke with us at length. He attended medical school at Cambridge University in England before switching careers to focus on herbalism, and although he does not have an MD degree, he has participated in designing research studies at Harvard Medical School. Treasure is a practicing clinical herbalist, a Member of the National Institute of Medical Herbalists in the UK (MNIMH), and a member of the American Herbalist Guild. He pointed out bias in the medical community and literature as well as specific flaws in the JAMA article, then recommended a different approach to the basic question of what to tell your doctor.

Getting solid advice about herbs before surgery

Treasure says, "Physicians usually do not know enough about herbs to give good advice about which herbs to continue taking and which to stop before surgery. In the medical literature, there is a bias against herbal medicines and a lack of education on the part of physicians. In the popular media, there is sensationalism and ignorance and push for readership. Hysterical stories about the dangers of herbs attract more readers than plain, fact-oriented articles."

Climate of opinion obscures the real issues

Unfortunately, this climate of opinion in both medical literature and the popular press tends to obscure the real issues of herbal use and potential interactions between herbs and drugs. According to Treasure, "When a patient is facing surgery, one group of physicians may say that garlic is the most dangerous substance in the world -- whereas another group of physicians cite placebo-controlled studies that say garlic doesn't work. But you can't have it both ways: that garlic is simultaneously powerful and dangerous as well as weak and ineffectual."

Foods also affect drug metabolism

Treasure points out that many foods also cause interactions with drugs. "Grapefruit juice affects the metabolism of drugs (including the blood-thinner Warfarin) by its effects on the liver and gut -- yet we don't hear a hue and cry that grapefruit juice should be prescription only or that patients should stop drinking it two weeks before surgery. Broccoli and the cabbage family contain compounds that affect drug metabolism, as strongly as St. John's wort in some cases, but we don't hear a call for patients to stop eating broccoli."

Physicians need better, accurate information

Because increasing numbers of Americans are using herbs, physicians need better, more accurate information both about the effects of herbs and potential interactions with drugs. Treasure applauds JAMA and the ASA for drawing attention to the need for physicians to learn about herbal medicines, but adds, "Physicians need to look at the literature in herbal pharmacology instead of reading hysterical reports that are largely unsubstantiated when evaluated by scientific criteria."

JAMA report not based on solid scientific evidence

Of the 122 references in the JAMA article, Treasure points out that only 59 are primary literature. Concerning the others, Treasure states, "There is an old joke in medical schools that the plural of anecdote is clinical evidence. It has happened that editorial musings have been quoted -- and then other people repeat the quote -- and no one goes back to check the original source. Or a journal publishes a letter about a potential interaction, and then other physicians write in saying, 'Me too, I had a patient,' and suddenly there is an entire climate of belief with no one doing a serious literature evaluation to establish what the risks actually are."

The real issues for herbs and surgery

According to Treasure, "Certain herbal remedies can interact both positively and negatively with certain drugs. If you are contemplating a surgical procedure, your surgical team needs to know what you are taking. Surgical nurses have become very aware of this and now tend to ask about both over-the-counter drugs and dietary supplements. So the first concern is to communicate what one is taking. The second is which herbs might be of consequence."

Herbs likely to affect surgery and anesthesia

According to Treasure, three basic kinds of potential effects are important for surgery and anesthesia:

  • hemostasis (coagulation and clotting)
  • sedative effects (which can amplify anesthesia)
  • metabolism of certain drugs

(Surgeons and anesthesiologists would probably add cardiovascular effects to that list.)

Treasure gave the following examples of these three kinds of effects. He did not characterize these examples as complete.


"Ginkgo inhibits the formation of clots, and is therefore inadvisable to take before surgery. However, a soon-to-be-published study failed to show any increase in bleeding time, either alone or in combination with aspirin in healthy volunteers.

"Garlic affects coagulation and thins the blood.

"Several Chinese herbs that come under general category of blood movers (a Chinese term) act as anticoagulants. Two examples would be dong quai and dan shen (red sage). These and other herbs can be subtle parts of a formula with a different, perhaps dramatic name."

Sedative effects

"Sedative herbs such as valerian and kava may increase the effects of anesthetic drugs and therefore influence the depth of anesthesia. A few experimental studies suggest this possibility. In rats who are taking barbiturates every night, the sleeping time increases for those also given valerian. However, most herbalists would argue that people are not the same as rats.

"In any case, it's common sense not to take a sedative herb before surgery. The risk is that people who are scared might take a calming herb to relieve their fear -- so it makes sense to warn people not to take them. However, sedative herbs are not likely to cause irreversible coma or other huge problems."

Metabolism of various drugs

"St. John's wort has been shown to affect the absorption and metabolism of certain important drugs, digoxin and cyclosporin in particular. Cyclosporin is used for transplants, digoxin for arrhythmias -- and their concentration in the blood is critical to their effectiveness."

Other herbs on the JAMA/ASA list

Echinacea: Treasure states, "The JAMA paper says echinacea causes complications for wound healing, which is opposite to the truth. There is no evidence for liver inflammation."

Ephedra, which is arguably the most controversial herb on the market today: Treasure agrees that cardiovascular integrity is important in surgery (blood pressure and heart rate/rhythm), then points out, "Sure ephedra affects the heart -- but physicians don't tell their patients to stop taking Sudafed before surgery." [Sudafed is an over-the-counter medicine that contains pseudoephedrine, one of the two main bioactive compounds in ephedra.] (However, see also our sidebar on ephedra and surgery.)

Ginseng: Treasure says, "If ginseng was a significant hypoglycemic, it would be used instead of insulin."

Licorice: Treasure observes, "Licorice has gotten a bad press -- mostly from concentrates in revolting things like chewing tobacco. There are no clinical reports of adverse effects from herbal use of licorice. It does have side effects, but there are no reports of therapeutic dosages of licorice root causing side effects."

Safety record for herbs

One of the common misconceptions among physicians is that herbs have not been tested for safety. In fact, Treasure states, "The main safety data for herbs comes from the fact that herbs have been used for thousands of years. In that process, the good guys have been picked up and the bad ones weeded out. The only problems this doesn't catch are the subtle, silent onset type. A few herbs that cause liver or kidney problems over a long period of time were missed. But the vast majority of herbs have been field tested for safety."

Treasure points out this is exactly equivalent to the kind of data the FDA accumulates to assess risks involved with pharmaceutical drugs, and says, "The FDA relies on community use to discover interactions. When people start dropping dead or getting liver disease, there is a time lag but we do discover it."

Safety testing of pharmaceutical drugs typically involves trials of approximately one thousand people -- but to discover a drug interaction that affects 1 in 3000 patients (which Treasure calls "a very high rate") one needs to have a clinical trial of at least ten thousand people taking both drugs. This is why some of the drugs that the FDA approves are later found to be unsafe.

Treasure says, "Even with the best will in the world, you can't catch all the problems." He cites the case of Rezulin and says, "It causes appalling liver disease. People were winding up on liver transplant lists. You don't hear any hue and cry about problems with prescription drugs -- but we do still hear about ephedra, which it is arguable if ephedra has killed anyone even though millions of people have taken it. But Seldane was killing people and there was no sensational press."

Natural not the same as safe

Treasure also points out that natural is not the same as safe. Traditional use has demonstrated the overall effectiveness and safety of most herbs used today. However, some herbs are now being used in ways quite different from traditional use. Treasure says herbalists don't use St. John's wort as an antidepressant. Instead, "It's a wound wort."

According to Treasure, side effects from herbs like ginkgo and St. John's wort are a new phenomenon caused by concentrating herbs into powders and extracts. He says, "When they were taken as teas or tinctures, people didn't get headaches or tummy aches. Herbs are gentle but they do have profound effects. Today's pill consumer mentality has in no small part created side effects that you don't see in normal clinical practice. The more we make herbs like drugs, the more they start having side effects."

The trend to standardization of herbs has two aspects. One is quality control, from growing conditions through harvesting to processing. Another is that many "standardized" products often contain stronger concentrations of one or more specific active ingredients -- which makes them more like manipulated, processed pharmaceutical drugs. So while physicians may think that's great, herbalists are more likely to be concerned. One important foundation of herbalism is: "The active principle is the whole plant."

A different approach for those facing surgery

Treasure's advice to patients: "Yes, absolutely: Tell your physician about the herbs you are taking. Better still, also consult a practitioner who is qualified and experienced in the use of herbs concurrently with drugs."

According to Treasure, most naturopaths and clinical herbalists deal with patients who come to them taking a basketful of drugs. Patients say, "I'm taking digoxin and a beta blocker and diuretic, and I'm pretty much stable but I'd like to start using hawthorn. I'd like to reduce my drug load." Rarely do patients go to a physician and say, "I'm taking garlic and hawthorn and think I might need digoxin, what do you think?"


American Society of Anesthesiologists. "What You Should Know About Herbal Use and Anesthesia." American Society of Anesthesiologists, pamphlet, 1999.

Healthy.net. "Herbal Medicines Can Affect Surgery." Website article, July 2001. healthy.net/asp/templates/news.asp?Id=2678.

Natural Products Insider website. "JAMA: Herb Use May Interfere with Post-Op Recovery." Website article, 10 July 2001. www.naturalproductsinsider.com/hotnews/17h1016177.html.

Paul Thomas, EdD and Registered Dietitian (RD). Personal communication, 24 July 2001.

Jonathan Treasure, Member of the National Institute of Medical Herbalists in the UK (MNIMH), and member of the American Herbalist Guild. Personal communication, 24 July 2001.

Information in the two website articles was based on a study that appeared in the 11 July 2001 edition of the Journal of the American Medical Association, (286:208-16, 2001). The study also appears on the JAMA website (jama.ama-assn.org) in an area limited to JAMA subscribers.end-of-story




Health benefits Safety Reading labels Ask the supplier Standards & regulations Contact us

(c) Copyright 1999-2003 Dietary Supplement Quality Initiative. For permission to reprint, please contact our editor.