Curious About Herbal Supplements? Do Your Homework First.

PillsA recent article by Roger Byard in the Journal of Forensic Science about the potential forensic significance of herbal medicines (1) caught my attention. I was curious about the phrase “potential forensic significance”; what does that mean exactly? It became clearer to me when I read Byard’s recommendation that “the role of herbal medicines in forensic practice needs to be more clearly defined as deaths may be occurring where herbal medicines have made a significant, but as-yet unrecognized contribution”. He points out that herbal medicines do not require prescriptions, so access is largely unrestricted. However, the unintended effects of herbal medicines are often uncharacterized and unquantified, and the potential contribution of these effects to a death are not always considered during a forensic investigation.

In many countries, herbal medicines have few standards in terms of formulation, purity, efficacy or packaging. Surveys have found that levels of principal ingredients in herbal preparations can vary dramatically from brand to brand (2–5). Under US federal laws, any treatment intended to prevent or treat a condition is regulated as a drug, but because herbal preparations are advertised not as medicines but as dietary supplements, they do not require regulation by the Federal Drug Administration. Thus, there is little impetus to fully characterize and quantify the intended and unintended effects of herbal medicines.

What are some of these unintended effects? In his paper, Byard states that herbal medicines may “be responsible for a range of symptoms and signs that may confuse the clinical presentations of cases” and “contain toxic substances that can result in serious illness or even death”. He reviews the toxic substances found in some herbal medicines, reasons why these toxins may be present and the serious illnesses and adverse effects that can arise as a result. It was an eye-opening article. I learned that certain remedies contain heavy metals such as mercury, lead, thallium, cadmium, copper, iron, manganese, nickel, zinc and arsenic and that acute lead, arsenic and mercury poisonings have been reported. In an analysis of 251 herbal products from stores in California, 36 contained arsenic, 35 contained mercury and 24 contained lead (6). Other hazardous substances found in herbal remedies include atropine or atropine-like substances, digoxin-like substances, hepatotoxins, and compounds with anticholinergic effects such as scopolamine. Herbal medicines have been linked to heavy metal poisonings, hepatic disease, myocardial infarction, seizures, liver failure, spontaneous cerebral hemorrhage, coma, death and many other serious medical problems.

To forensic scientists or medical examiners investigating a death, the presence of any toxins can be important information. Investigators collect information about the person’s prescription drug use and consider this information when determining cause of death. However, often there is no medical history of herbal supplement use and detection of these compounds may be difficult because the nature of the substance may be unknown or the levels may be near the limit of detection. For this reason, Byard recommends that investigators include all herbal medicines on the list of drugs found at the death scene and consider the risks associated with these herbal medicines when determining cause of death.

So, why do some herbal remedies contain these harmful substances? Byard lists many reasons. The starting material may contain the toxin naturally, or a component may be grown or stored in a contaminated environment. Alternatively the component may be misidentified or the component name was misinterpreted from the original text. Also, the herbal remedy components may be processed incorrectly. For example, aconite root is available in a dry form and must be soaked and boiled to reduce toxicity; failure to do this can lead to serious cardiac problems and death. The component may be contaminated by herbicides or pesticides, mycotoxins, microorganisms, insects or heavy metals.

Other reasons are not so innocent. During preparation, certain components may be replaced with other components with higher toxin levels. For example, if an herb is expensive or scarce, a cheaper herb may be substituted. The hazardous chemicals might not be present in the herbal remedy components but are added to the preparation intentionally to increase efficacy. In a study performed in Taiwan (7), up to 24% of herbal medicines tested were adulterated with prescription or nonprescription drugs that were not mentioned on the packaging, even though this practice is illegal in that country. Such adulterations, whether intentional or unintentional, have had serious effects such as allergic reactions, aplastic anemia, significant hypoglycemia, Cushing syndrome, coma and others.

Just as conventional prescription and nonprescription drugs can interact, herbal preparations can have potentially dangerous interactions with common drugs, increasing or decreasing a drug’s activity, absorption or metabolism. An often-quoted example used in many toxicology classes is “St. John’s wort babies” born to mothers who were taking oral contraceptive pills and St. John’s wort, which induces several cytochrome P450 isoforms, increases metabolism of the active ingredient and makes the prescription less effective. Unfortunately, most examples of drug interactions are not so harmless. Other examples involving St. John’s wort and other herbal medicines include reduced anticoagulation by warfarin, organ transplant rejection due to decreased cyclosporin activity and lethal interactions with monoamine oxidase inhibitors.

Most of us are not forensic scientists or medical examiners. What does this paper mean to us?

I cannot speak for others, but for me, the paper raises a good question: “Can we assume that herbal medicines, which are touted as natural and in many cases have been used for thousands of years, are safe?” A lot of advertisements that I see for these remedies seem to have an undertone of “if it is natural, it can’t be bad for you”, but is that really true? As my husband is fond of pointing out “Botulism toxin is natural, but I certainly wouldn’t want to ingest it.”

What I gleaned from this paper isn’t that all herbal medicines are bad but that you have to be careful. Before pursuing any herbal remedies, do your research and know what you’re ingesting, what standards were applied during manufacturing and how the components could interact with other conventional or nontraditional medicines. Also, tell your doctor what supplements you are taking so that he or she is aware of all of your medications, prescription and nonprescription, and can monitor any potential drug interactions or side effects. It could save your life.


  1. Roger W. Byard (2010). A review of potential forensic significance of traditional herbal medicines. Journal of Forensic Sciences, 55 (1), 89-92 : 10.1111/j.1556-4029.2009.01252.x
  2. Good Housekeeping Institute. New Good Housekeeping Institute study finds drastic discrepancy in potencies of popular herbal supplement. News release, Consumer Safety Symposium on Dietary Supplements and Herbs, New York City, March 3, 1998.
  3. Gurley, B.J. et al. (2000) Content versus label claims in ephedra-containing dietary supplements. Am. J. Health-Syst. Pharm. 57, 963–9.
  4. Garrard, S. et al. (2003) Variations in product choices of frequently purchased herbs: Caveat emptor. Arch. Intern. Med. 163, 2290–5.
  5. Hasegawa, G.R. (2000) Uncertain quality of dietary supplements: History repeated. Am. J. Health-Syst. Pharm. 57, 951.
  6. Ko, R.J. (1998) Adulterants in Asian patent medicines (letter). N. Engl. J. Med. 339, 847.
  7. Huang, W.F., Wen, K-C. and Hsaio, M-L. (1997) Adulteration by synthetic therapeutic substances of traditional Chinese medicines in Taiwan. J. Clin. Pharmacol. 37, 344–50.
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    Terri Sundquist

    Terri has worked as a Scientific Communications Specialist at Promega Corporation for more than 13 years, and prior to that, spent more than 5 years solving problems and answering questions as a Promega Technical Services Scientist. She graduated with B.S. degrees in Chemistry and Biology at the University of Wisconsin—River Falls, then earned her M.S. in Molecular Biology from the Mayo Graduate School in Rochester Minnesota.


    1. The Herbal Remedies for Health entry (posted on Friday, January 15) on the Herbal Supplement site mentioned above lists several good examples of the types of risks and interactions that are not often discussed. It’s unfortunate that all sources of information about herbal supplements do not have similar cautions.

  1. Hi Terri,

    The Memorial Sloan-Kettering Cancer Center has a great searchable database of herbal remedies. You can search for a common herb, like Valerian root, find the “active compounds”, what drugs it interacts with, whether it inhibits cytochrome P450 activity, etc. The site is here: I recommend checking it out before taking any herbal supplement.


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