We designed this study as a multicenter, randomized, double blinded and placebo-controlled clinical trial. The aim of the study is to evaluate the clinical efficacy, safety and control of recurrence rate of psoriasis with blood stasis syndrome.

Psoriasis is a chronic, relapsing, inflammatory, multisystem disease characterized by infiltration of inflammatory cells, hyperplasia of epidermal keratinocytes, and abnormal differentiation. Latest data estimate that the prevalence of psoriasis in adults has increased to 11.43%, which shows that the control and treatment of psoriasis is still insufficient. Recent studies showed that traditional Chinese medicine (TCM) is one of the effective methods for the treatment of psoriasis. More and more evidences support the recognition of psoriasis not only affects the skin, but also suffers a chronic multisystem inflammation. In addition, blood-stasis accumulates in meridians, viscera and limbs to form a variety of syndromes with psoriasis for so long, which similar to many metabolic related diseases. Therefore, the method of promoting blood circulation and removing blood stasis has always been the focus of TCM treatment and prevention of psoriasis. This multicenter, randomized, double-blind, placebo-controlled trial will provide high-quality clinical evidences for evaluating the efficacy, safety and recurrence rate of Taodan granule, a representative prescription for the treatment of psoriasis with blood stasis syndrome, in the treatment of psoriasis.

Inclusion Criteria:

1. Comply with the diagnostic criteria of Western medicine for psoriasis and the diagnostic criteria for TCM syndromes;
2. Skin lesions involve ≤10% BSA (the lesions are mainly located in the trunk and/or limbs, palm/sole, face/scalp, vulva area is not included);
3. Age between 18 and 65 years old;
4. Those who voluntarily participate in the study and sign informed consent.

Exclusion Criteria:

1. Patients with erythrodermic, arthritic, pustular or punctate psoriasis;
2. Other active skin diseases may affect the condition assessment;
3. Received research drugs, biological agents and immunosuppressive agents within 1 month;
4. 2 weeks of treatment with topical glucocorticoids, phototherapy, etc.;
5. During severe, uncontrollable local or systemic acute or chronic infections;
6. Patients with severe systemic diseases; or clinical test indicators in one of the following conditions: alanine aminotransferase or aspartate aminotransferase increased by >1.5 times the upper limit of normal; creatinine increased by 1.5 times the upper limit of normal; blood routine indicators (white blood cell count) Any one of the red blood cell count, hemoglobin amount, and platelet count) is below the lower limit of normal; or other laboratory abnormalities are judged by the investigator to be unsuitable for participation in the trial;
7. A history of malignant tumors and patients with primary or secondary immunodeficiency and hypersensitivity;
8. Such surgery will be required during major surgery or study during 8 weeks;
9. Pregnant or lactating women;
10. A person with a history of alcohol abuse, drug abuse or drug abuse;
11. Have a history of serious mental illness or family history;
12. Other reasons researchers believe that it is inappropriate to participate in this research.