Oral herbal medicines for psoriasis: a review of clinical studies

Various forms of complementary and alternative medicine are used in psoriasis. Among these, herbal medicines are frequently used as systemic and/or topical interventions either as a replacement for or in conjunction with conventional methods. The benefit of such use is unclear. This review is to provide an up-to-date review and discussion of the clinical evidence for the main kinds of herbal therapies for psoriasis. Searches of the biomedical databases PubMed (including MEDLINE), EMBASE and CINAHL were conducted in December 2011 which identified 32 clinical studies, all published in English. Twenty of these primarily tested topical herbal medicines and were thus excluded. The 12 studies that evaluated systemic use of herbal medicines were included in the review. Four were case series studies and the other 8 were controlled trials. In terms of interventions, 4 studies tested the systemic use of plant oils combined with marine oils and 8 studies tested multi-ingredient herbal formulations. The clinical evidence for plant and animal derived fatty acids is inconclusive and any benefit appears to be small. For the multi-herb formulations, benefits of oral herbal medicines were shown in several studies, however, a number of these studies are not controlled trials, a diversity of interventions are tested and there are methodological issues in the controlled studies. In conclusion, there is promising evidence in a number of the studies of multi-herb formulations. However, well-designed, adequately powered studies with proper control interventions are needed to further determine the benefits of these formulations. In addition, syndrome differentiation should be incorporated into trial design to ensure effective translation of findings from these studies into Chinese medicine clinical practice.