Risks of herbal medicinal products.

PURPOSE: Herbal medicinal products (HMPs) are again highly popular. Their current popularity renders the assessment of their safety an urgent necessity.
METHOD: Narrative review using examples only.
RESULTS: Constituents of HMPs can be toxic and numerous examples of liver, kidney or other organ damage are on record. All HMPs contain a range of pharmacologically active constituents, and users of HMPs often combine HMPs with prescribed drugs. Thus herb-drug interactions are a real possibility. In most countries, HMPs are not submitted to stringent regulation and control. Thus unreliable quality can be a problem. In particular, this poses a risk when HMPs are contaminated (e.g. with heavy metals) or adulterated (e.g. with prescription drugs). The medical literature holds numerous examples for all of these scenarios and some are used in this article to illustrate the above points. As this area is grossly under-researched, it is rarely possible to define the size of the problem.
CONCLUSIONS: It is concluded that the widespread notion of HMPs being inherently safe is naive at best and dangerous at worst. More research is required to minimise the risk HMPs may pose to consumers' health. Copyright 2004 John Wiley & Sons, Ltd.