Ther Umsch. 2002 Jun; 59(6): 283-91.

[Adverse effects and interactions of phytotherapeutic drugs]

Iten F, Reichling J, Saller R.

Abteilung für Naturheilkunde, UniversitätsSpital Zürich.

The significantly increased sales figures many phytopharmaceuticals have achieved during the last years prove the confidence that a great part of the population has in herbal remedies. This is primarily due to the wide-spread opinion that herbal remedies are free from side-effects. The long tradition and presumed 'natural' origin are no guarantee for safety in the treatment with herbal remedies. Even if a large proportion of the undesirable events is traceable to falsifications, impurities and lacking quality controls, herbal drugs with controlled quality should not be generally classified as harmless. In the meantime it has been possible to prove the presence of active substances with toxic and cancerogenic properties in various phytopharmaceuticals. Interactions with other drugs have been documented in a number of notes, where phytopharmaceuticals could influence the blood plasma level of various drugs, presumably by activating or inhibiting the cytochrom-P450-system. At present, especially data about adverse effects during long-term administration of herbal remedies are under-represented. Particularly because of their presumed harmlessness they often are prescribed in the case of chronic diseases and then taken over a longer period of time. The frequency of undesirable effects of phytopharmaceuticals is remarkably low, even if the present lack of data about side-effects is considered.