Systematic review: hepatotoxic events associated with herbal medicinal products

Large proportions of patients use herbal medicinal products, and encouraging data in terms of effectiveness exist for some of these. One aspect, however, which is still largely under-investigated is the question of potential harm.

To review the recent evidence on hepatotoxic events associated with the use of herbal medicinal products.

Systematic literature searches were performed on Medline, Embase, The Cochrane Library, Amed and Ciscom. To identify additional data, searches were conducted by hand in relevant medical journals and in our own files. The screening and selection of articles and the extraction of data were performed independently by the two authors. There were no restrictions regarding the language of publication. In order to be included articles were required to report data on hepatotoxic events associated with the therapeutic use of herbal medicinal products.

Single medicinal herbs and combination preparations are associated with hepatotoxic events. Clinically, the spectrum ranges from transient elevations of liver enzyme levels to fulminant liver failure and death. In most instances hepatotoxic herbal constituents are believed to be the cause, while others may be due to herb-drug interactions, contamination and/or adulteration.

A number of herbal medicinal products are associated with serious hepatotoxic events. Incidence figures are largely unknown, and in most cases a causal attribution is not established. The challenge for the future is to systematically research this area, educate all parties involved, and minimize patient risk.