An ointment made from indigo naturalis, a dark blue plant-based powder used in traditional Chinese medicine, appears effective in treating plaque-type psoriasis, according to a report in the November issue of Archives of Dermatology.
Psoriasis is a chronic skin disease for which no cure exists, only therapies that bring it into remission, according to background information in the article. "Traditional Chinese medicine is one of the most frequently chosen alternative therapies in China and Taiwan, and psoriasis has been treated for centuries with topical and oral herbal preparations," the authors write. "Indigo naturalis is one of the Chinese herbal remedies that has been reported to exhibit potential antipsoriatic efficacy. However, long-term systemic use has been occasionally associated with irritation of the gastrointestinal tract and adverse hepatic [liver] effects."
Yin-Ku Lin, M.D., of Chang Gung Memorial Hospital and Chang Gung University, Taoyuan, Taiwan, and colleagues conducted a randomized trial of an ointment containing indigo naturalis in 42 patients with treatment-resistant psoriasis. Participants enrolled in the study between May 2004 and April 2005 and applied the indigo naturalis ointment to a psoriatic plaque on one side of their body (usually on the arm, elbow, leg or knee) and then a non-medicated ointment to a parallel plaque on the other side of their body. The researchers assessed and photographed patients' skin plaques at the beginning of the study and again after two, four, six, eight, 10 and 12 weeks.