Introduction
Risks of Herbal Supplements
Perioperative Concerns
Herb/Drug Interaction by Medication Class
Assessing a Patient's Use of Supplements
Dietary Supplement–Drug Information Resources

Introduction

Herbals are the most common type of dietary supplement. Herbs have been used medicinally since ancient times.  For example, St. John's Wort was used to treat mood disorders as early the 5th century BC. The popularity of herbal medicines has been growing rapidly since the 1960s and today represents a multibillion dollar industry. Interestingly, over 100 of the pharmaceuticals currently used in conventional medical practice are derived from plants. 

Today there are 1500 to 1800 herbals sold in the U.S. Although many of these supplements appear to be safe, some commonly-used substances have important side effects and interact both with standard pharmaceuticals and other supplements.  Supplements received a lot of attention in the public media when ephedra was found to be linked to several deaths, and was subsequently banned by the Food and Drug Administration (FDA) in 2003.

Herbals are just one type of dietary supplement as defined by the FDA. According to the FDA, a dietary supplement is defined as a product that contains one or more dietary ingredient such as: 

• a vitamin or a mineral,
• an herb or other botanical,
• an amino acid,
• a dietary substance intended to increase the total dietary intake
• a concentrate, metabolite, constituent, extract
• a combination of the above ingredients

Risks of Herbal Supplements

There is no systematic scientific methodology to evaluate possible interactions between herbal supplements and medications that might be prescribed by a physician.  As a result, information and recommendations are largely based on the aggregate of animal studies, case reports, historical contraindications, extrapolation from basic pharmacology data, and the occasional clinical trial. Much of the information on adverse effects related to herbal supplements has focused around the following problems:

• Liver toxicity from pyrrolizidine alkaloid compounds found in some plants
• Nephrotoxity induced by some Chinese herbs, in particular aristolochia, which may also be associated with urothelia cancers.
• Cardiac events have been associated with ephedra alkaloids.  Ephedra has been banned by the FDA and is no longer legally available in the USA.  Nevertheless, all clinicians should still be aware of its risks, as patients may acquire ephedra when abroad.

Warfarin is the most common physician prescribed pharmaceutical cited to have negative interactions with herbals, and St. John's Wort is the most frequent herbal product reported as being associated with adverse interaction effect with drugs.

In addition, herbal supplements that are not known to cause adverse effects when taken at the recommended doses, may have toxic effects if extremely high doses are used. Licorice and ginseng in particular have been associated with toxicities from overuse.

The Food and Drug Administration has classified the following supplements as high risk and therefore need be avoided by all patients:

• Ephedra or ephedrine
• Chaparral
• Comfrey
• Gamma butyrolacone

Perioperative Concerns

The assessment of the patient scheduled to undergo sedation for a procedure includes a history and physical exam.  Many patients do not tell their doctor about dietary supplements they may be taking in part because physicians may not be as knowledgeable about supplements, and patients may fear the physician will be unhappy about the patient using nonconventional therapy. However, doctors and nurses need to know if the patient is taking any supplements because the risk of complications from herbal supplements may be elevated in the perioperative period.  This is because of potential interactions between herbals the patient is taking and the anesthesia drugs and other medications that may be administered during the procedure.  Also, herbs may contain contaminants and/or other unknown ingredients.

Rare complications that might in part be due to supplements include myocardial infarction and stroke (e.g. ephedera) liver injury (e.g., echinacea; kava), ineffective anticoagulation and bleeding (e.g., garlic and ginko), prolonged or inadequate anesthesia (e.g., kava), and rejection of organ transplant (e.g. St. John’s wort).  As a result it is generally recommended to avoid herbal supplements for 2 weeks prior to a surgical procedure and anesthesia.

The following is a list of common supplements that are of particular concern with regard to the perioperative period.  (Follow the link for detailed information on each item.)

• Most commonly used by US adults in 2002 National Health Interview Survey (NHIS) and known to affect surgical outcomes:
  • Echinacea
  • Ephedra
  • Feverfew
  • Garlic
  • Ginger
  • Ginseng
  • St. Johns Wort

• Other supplements of concern:
  • Chondroitin
  • Glucosamine
  • Fish oil
  • Ginkgo biloba
  • Goldenseal
  • Kava
  • Licorice
  • Milk thistle
  • Saw Palmetto
  • Valerian
  • Vitamin E

Assessing a Patient's Use of Supplements

Data from 2002 National Health Interview Survey (NHIS) Alternative Medicine Supplement reveal that nearly 19 percent of American adults used an herb or other natural supplement in the previous year. Other estimates place the number of regular users as high as 25 percent. 

Individuals who use herbal supplements are more likely to be white females, 34 to 64 years of age who are more educated, have moderate income or above, are current alcohol users, live in the Southern or Western region of the U.S., and have chronic medical conditions or functional limitations.

Physicians seldom prescribe herbs or dietary supplements and most patients do not consider them as drugs, therefore 60 to 70% do not routinely tell health care providers that they are using these therapies.  Worth noting however is that over half of these individuals surveyed report that they fail to disclose their use of alternative therapies because their physicians don't ask.

Use of herbal and dietary supplements can be determined as part of the documentation of the patient's medical history done during the preoperative assessment. It is recommended that the practitioner approach the issue in a non-judgmental way that encourages the patient to discuss their supplement use. Questions can also be included in the medical intake questionnaire that a patient fills out before the appointment. These might include:

• Please list all of the prescription and over-the-counter medications you are currently taking.
• Are you taking any herbal supplement? (Please list)
• Are you taking any food supplements? (Please list)
• Are you taking any vitamins?  (Please list)
• Please circle any of medications listed below that you are taking or have taken in the last month.
  • Aspirin
  • Steroids
  • Diet Pills
  • Pain pills

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Sources

Ang-Lee M et al. Herbal Medicines and Perioperative Care. JAMA 2001;286:208-16.

Barnes, PM, Powell-Griner, E, McFann, K, Nahin RL. Complementary and alternative medicine use among adults. Advance Data From Vital and Health Statistics, US Dept of Health and Human Services, Rockville, MD 2004.

Flanagan K. Perioperative Assessment: Safety Considerations for Patients Taking Herbal Products. Journal of PeriAnestheisa Nursing. 2001;16:19-26.

Gardiner P et al. Herbal and dietary supplement-drug interactions in patients with chronic illnesses. Am Fam Physician. 2008;77(1):73-78.

Implementation of the Dietary Supplement Health and Education Act (DSHEA) of 1994. Food and Drug Administration. Updated August 6, 2009. http://www.fda.gov/NewsEvents/Testimony/ucm115082.htm

Johnston BA. Herbalgram. American Botanical Council. 2000;48:65-72.

Medline Plus: Drugs, Supplements, and Herbal Information. http://www.nlm.nih.gov/medlineplus/druginformation.html

Saper R et al. Overview of Herbal Medicine. UptoDate. 2009.

What You Should Know About Your Patients' Use of Herbal Medicines and other Dietary Supplements. ASA.  2003.

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Last Updated October 16, 2009