Patient Handout: Herbal Supplements—Safety

Herbal supplements are a type of dietary supplement (see box below) that contain herbs, either singly or in mixtures. An herb (also called a botanical) is a plant or plant part used for its scent, flavor, and/or therapeutic properties.

Herbs have a long history of use and of claimed health benefits. If prepared and used correctly, the safety of herb use has generally been good; however, problems have been reported. This fact sheet contains points you should consider for your safety if you use, or are thinking about using, herbs for health purposes.

About Dietary Supplements

Dietary supplements were defined in a law passed by Congress in 1994. A dietary supplement must meet all of the following conditions:

  • It is a product (other than tobacco) intended to supplement the diet, which contains one or more of the following: vitamins; minerals; herbs or other botanicals; amino acids; or any combination of the above ingredients.
  • It is intended to be taken in tablet, capsule, powder, softgel, gelcap, or liquid form.
  • It is not represented for use as a conventional food or as a sole item of a meal or the diet.
  • It is labeled as being a dietary supplement.

Key points

• It’s important to know that just because an herbal supplement is labeled "natural" does not automatically mean it is safe or without any harmful effects. For example, the herbs chaparral and comfrey have been linked to serious liver damage.

• Herbal supplements can have drug-like effects. Therefore, they can cause medical problems if not used correctly or if taken in large amounts. In some cases, people have experienced negative effects even though they followed the instructions on a supplement label.

• Women who are pregnant or nursing should be especially cautious about using herbal supplements, because these products have not been tested in pregnant and nursing women and their effects are not known. This caution also applies to treating children with herbal supplements.

• It is important to consult your health care provider before using an herbal supplement, especially if you are taking any medications (whether prescription or over-the-counter). Some herbal supplements are known to interact with medications in ways that cause health problems. Even if your provider does not know about a particular supplement, he can access the latest medical guidance on its uses, risks, and interactions.

• If you use herbal supplements, it is best to do so under the guidance of a medical professional who has been properly trained in herbal medicine. This is especially important for herbs that are part of an alternative medical system, such as the traditional medicines of China, Japan, or India. (Alternative medical systems are built upon complete systems of theory and practice, and have often evolved apart from and earlier than the conventional medicine that is practiced in the United States.)

• In the United States, herbal and other dietary supplements are regulated by the Food and Drug Administration (FDA) as foods. This means that they do not have to meet the same standards as drugs and over-the-counter medications for proof of safety and effectiveness. Although many dietary supplement companies manufacture products according to strict quality standards, the FDA has proposed new Good Manufacturing Practices for dietary supplements that will take effect soon.

• The active ingredient(s) in many herbs and herbal supplements are not known. There may be dozens, even hundreds, of such compounds in an herbal supplement. Scientists are currently working to identify these ingredients and analyze products. Identifying the active ingredients in herbs and understanding how herbs affect the body are important research areas for the National Center for Complementary and Alternative Medicine (NCCAM).

• Published analyses of herbal supplements have found differences between what is listed on the label and what is in the bottle. This means that you may be taking less—or more—of the supplement than what the label indicates. Also, the word "standardized" on a product label is no guarantee of higher product quality. Because of this variability, if you find a product that works for you, you should stick with it.

• Some herbal supplements have been found to be contaminated with metals, unlabeled prescription drugs, micro-organisms, or other substances.

• There has been an increase in the number of web sites that sell and promote herbal supplements on the Internet. The Federal Government has taken legal action against a number of company sites for posting incorrect or deceptive claims.

For more information

It is important to know how to evaluate dietary supplements claims. Some sources are listed below.

NCCAM Clearinghouse
P.O. Box 7923
Gaithersburg, MD 20898-7923
Telephone: (888) 644-6226
Fax-on-demand service: (888) 644-6226
Web site:

The NCCAM Clearinghouse provides information on complementary and alternative medicine and on NCCAM. Services include fact sheets, other publications, and searches of federal databases of scientific and medical literature. The Clearinghouse does not provide medical advice, treatment recommendations, or referrals to practitioners.

U.S. Food and Drug Administration (FDA)
Center for Food Safety and Applied Nutrition
Telephone: (888) 723-3366
Web site:

Information includes "Tips for the Savvy Supplement User: Making Informed Decisions and Evaluating Information" and updated safety information on supplements. If you have experienced an adverse effect from a supplement, you can report it to the FDA’s MedWatch program, which collects and monitors such information, at (800) FDA-1088 or

Office of Dietary Supplements (ODS)
Web site:

The Office’s information, offered via its web site only, includes the International Bibliographic Information on Dietary Supplements (IBIDS), a searchable database of citations to peer-reviewed scientific literature on dietary supplements (go to, select "Health Information").

CAM on PubMed
Web site:

CAM on PubMed, a database developed jointly by NCCAM and the National Library of Medicine, offers citations to articles in science-based, peer-reviewed journals on complementary and alternative medicine. Most citations include abstracts, and many link to the full text of articles.

Adapted from: National Center for Complementary and Alternative Medicine, National Institutes of Health. Available at: