Health risks associated with the use of herbal medicinal products (HMPs) are often an emotionally discussed issue. The topic is, however, important not least because of the present popularity of HMPs. This article aims to provide a factual overview of this complex subject. The evidence relating to the toxicity, interactions and quality of a number of HMPs is reviewed. Toxicity data indicate that some HMPs have the potential to cause serious adverse events and fatalities. HMPs affect pharmacokinetic and pharmacodynamic factors and thus cause herb-drug interactions. Reports of HMPs affected by contamination, adulteration or substitution of botanical material have repeatedly caused concern. Asian HMPs are most often implicated. It is concluded that HMPs are not free of risk. More research and more information are required in order to maximize consumers' safety.