FWD 2 ABC-AHP-NCNPR Botanical Adulterants Program Publishes Review of Skullcap Adulteration

HerbalEGram: Volume 9, Number 3, March 2012

ABC-AHP-NCNPR Botanical Adulterants Program Publishes Review of Skullcap Adulteration

The substitution and adulteration of skullcap with germander is a challenge that has plagued the herb industry in the United States and elsewhere for over 30 years, and the problem still persists today, according to an article in the recently released Winter 2012 issue of HerbalGram (#93).1 

In the article, noted botanist, author, and photographer Steven Foster traces the roots of common skullcap (Scutellaria lateriflora) adulterants, which can include inferior-grade, mislabeled, and—occasionally—potentially toxic substances. He continues with a discussion of modern cases of skullcap adulteration and suggests methods of verifying the herb’s authenticity. 

In a 2011 study featured in Analytical and Bioanalytical Chemistry, researchers at USDA's Food Composition and Methods Development Laboratory at the Beltsville Human Nutrition Research Center in Maryland found that of 13 skullcap-containing dietary supplements tested (all of which were purchased through the Internet) only 5 had a measurable amount of true skullcap.2 Four supplements contained the potentially toxic American germander (Teucrium canadense)—also referred to as wild germander, wood sage, and wild basil—which has been a known adulterant of skullcap products since the 1980s. Three supplements contained very low concentrations of skullcap and one sample contained Chinese skullcap (S. baicalensis) rather than the American species (S. lateriflora). 

Skullcap (also spelled “scullcap”)—which has been used for centuries as a mild sedative and so-called “nerve tonic”—received international attention in the 1990s when some herbal products that claimed to contain it were associated with several cases of liver dysfunction. Analyses later revealed the source of toxicity to be European germander (T. chamaedrys), an additional known skullcap adulterant. 

Foster also wrote a short, non-bylined article in HerbalGram in 1985 alerting members of the industry about the skullcap-germander substitution problem.3 In his new article, he describes the 2011 USDA study, as well as a scientific paper from 1992 that first established germander as the source of harm. 

“A clear chronological relationship was established between ingestion of germander and the onset of hepatitis,” Foster wrote. “Liver dysfunction was reversed after use of germander products was discontinued.”

“In 2010 and 2011, I gave about a dozen speeches about adulteration problems in the global herb market, and I referred to the skullcap-germander problem as an example of a former problem,” said ABC Founder and Executive Director Mark Blumenthal. “However, I was disappointed to read the report from the USDA scientists this past summer showing that skullcap is still being adulterated with germander!”

There are those who believe that skullcap and germander can look similar because they are both members of the mint family (Lamiaceae or Labiatae). Foster, and various herbal experts, believe that their physical characteristics are distinct enough to warrant an accurate identification with the naked eye, i.e., in the field. 

According to an extensive quality control and therapeutic monograph on skullcap (“Skullcap Aerial Parts, Scutellaria lateriflora L.”) produced by the nonprofit American Herbal Pharmacopoeia (AHP), the relatively comparable appearances of skullcap and other herbs can lead to accidental adulteration.4 The AHP monograph states, “Skullcap has historically been adulterated with various species of the potential hepatotoxic germander (Teucrium canadense, T. chamaedrys) due to morphological similarity between S. lateriflora and T. canadense.” 

Foster recommends using the AHP monograph as a guide for properly identifying skullcap and germander species. “The most comprehensive and detailed information source on the topic is the 2009 AHP skullcap monograph which includes exhaustive information, illustrations, photographic images, and chromatograms on authentication, morphological difference, and chemical differences … of S. lateriflora, with an extensive discussion of adulterants.” 

The recent HerbalGram article contains line drawings from the Missouri Botanical Garden (MBG) of skullcap and germander parts in order to help differentiate the plants, as well as Foster's beautiful 4-color photography of both plants. The drawings are taken from a book on botanical identification produced by MBG and ABC.5 

The proper identification of herbal ingredients is paramount in helping prevent adulteration and protecting consumers. As Foster concludes, “Persistent, long-standing instances of adulteration and mislabeling of improperly identified botanicals, such as in the instance of skullcap adulteration with T. canadense, must be resolved to ensure that consumers get the herbal products they expect.” 

“In our view, all manufacturers of herbal dietary supplements and herbal teas, in the US and globally, should read this article and the AHP monograph on skullcap to ensure that they are taking adequate measures to confirm that their skullcap raw material has not been confused with germander,” said ABC's Blumenthal. 

Foster's article is the second in a series of publications to come from the ABC-AHP-NCNPR (National Center of Natural Products Research) Botanical Adulterants Program, a nonprofit educational consortium that includes numerous third-party analytical laboratories and experts on herbs and herbal quality control. The program is preparing a technical laboratory guide to assessing skullcap-germander adulteration, as well as a variety of reviews and technical publications on the adulteration of other herbs, herbal extracts, and essential oils. The ABC-AHP-NCNPR Botanical Adulterants Program is an industry-sponsored, self-regulated, educational initiative designed to help members of the global herbal supply and finished products community obtain increased access to information that can help ensure the accurate identity and quality of plant-based ingredients and products.

Tyler Smith


1. Foster S. The adulteration of skullcap (Scutellaria lateriflora) with American germander (Teucrium canadense). HerbalGram. 2012:93;34-41. Available here.

2. Sun J, Chen P. A flow-injection mass spectrometry fingerprinting method for authentication and quality assessment of Scutellaria lateriflora-based dietary supplements. Analytical and Bioanalytical Chemistry. 2011;401(5):1577-84.

3. Foster S. Scullcap substitution. HerbalGram. 1985:2(3);3.

4. Upton R, ed. American Herbal Pharmacopoeia and Therapeutic Compendium: Skullcap Aerial Parts. Scotts Valley, CA: American Herbal Pharmacopoeia; 2009.

5. Applequist W. The Identification of Medicinal Plants: A Handbook of the Morphology of Botanicals in Commerce. Austin, TX, and St. Louis, MO: American Botanical Council and Missouri Botanical Garden Press; 2006.