Risk assessment of herbal preparations containing St John's wort

Abstract

People use herbal preparations (food supplements and herbal tea) with St John’s wort, amongst others to feel and sleep better. However, these herbal preparations can reduce the effect of medicines, or enhance their effect. These interactions can have serious health effects. Herbal preparations with St John’s wort, for example, reduce the effect of certain medicines prescribed for fungal or viral infections and for cancer (chemotherapy). The effect of certain consciousness-lowering agents, e.g. sedative medicines, and consciousness-stimulating agents, e.g. antidepressants, is actually enhanced. The use of herbal preparations with St John’s wort may also pose health risks when used alone and not in combination with medicines. For example, the skin can be damaged faster (sunburn) if people sit in the sun after using St John’s wort. Other effects such as dizziness, diarrhea and anxiety have also been reported after the use of herbal preparations containing St. John's wort. It is not known what effects occur after people use these herbal preparations for a long time. There is also insufficient information available to determine whether the use of St John’s wort during pregnancy is safe for the unborn child. Moreover, the composition of herbal preparations containing St John’s wort can vary greatly, and it is often not known what exactly is in it. This makes it difficult to estimate the effects of a product. RIVM draws these conclusions based on a risk assessment on behalf of the Ministry of Health, Welfare and Sport (VWS). RIVM advises consumers to be cautious with the use of herbal preparations containing St John’s wort, and to not use these products in combination with medicines. RIVM advises VWS to draft legislation on the use of St John’s wort in herbal preparations.