Psoriasis vulgaris is a skin disease with a multi-factorial genesis wh
ere no causal treatment is known. Based on our own pilot studies, we s
et up a randomized, placebo-controlled clinical trial to evaluate the
efficacy and safety of Mahonia aquifolium bark extract in psoriasis pa
tients. From autumn 1990 to spring 1992 we treated 82 patients of all
severity gradings, recruited by 22 family physicians. Patients were to
ld to apply two types of ointment (verum/placebo) one to the left side
of their body the other to the right. After an average treatment peri
od of four weeks, patients as well as physicians assessed the therapy'
s success on a three-level ordinal rating scale. Statistically signifi
cant differences (alpha = 5%) could be found for patients' but not for
physicians' assessments. Additional analyses show that treatment diff
erences are not significantly masked by parallel antipsoriatic therapi
es. Adverse drug reactions, such as itching and burning sensations and
'allergic reactions,' occured in four patients. Therefore, we regard
Mahonia aquifolium bark extract as a potent and safe therapy of modera
tely severe cases of psoriasis vulgaris.