According to a study published in the November issue of Archives of Dermatology, 2008 an effective treatment for plaque-type psoriasis can be found in traditional Chinese medicine. Yin-Ku Lin, M.D. (Chang Gung Memorial Hospital and Chang Gung University, Taoyuan, Taiwan) and colleagues found that an ointment based on the dark-blue, plant-based powder indigo naturalis can be used treat the skin condition.