[Herbal medicines--evidence and drug interactions in clinical practice]

We present an evidence-based literature review of five commonly used herbs in Denmark: St John's wort, ginkgo biloba, valerian, garlic, and ginseng. Various drug interactions are associated with the intake of some herbal medicines, and may result in many clinical conditions. We bring this to the attention of clinical practitioners. Attention to clinical practice and recommendations for discontinuation of the five herbs are given before surgery. Physicians should be aware of and report potential drug interactions and adverse effects, so as to throw more light on this subject.