牛皮癣是一种严重的慢性自身免疫性疾病，有时可能难以治愈或缓解。草药疗法一直被视为一种传统的治疗方法，可以帮助减轻症状。在使用任何草药治疗牛皮癣之前，您应首先咨询医生。
在研究了十分丰富的资料后，我们找到了以下一些牛皮癣草药外洗方：
1. vinegar and Chinese medicine water decoction: mix two tablespoons of vinegar with one cup of Chinese medicine water decoction, soak the affected part of skin in the mixture for 10-15 minutes, three times a day.
2. Coptis and golden cypress mixed decoction: using 30 grams of Huanglian, 30 grams of Jinlei, 20 grams of Zhuangfengzi, 10 grams of Huagaiqiao, 10 grams of Xubiezi. Decoct them together, filter out the liquid mixture, cool it, and then use it to wash the affected skin.
3. Aloe Vera and Centella Asiatica: mix equal parts of Aloe Vera and Centella Asiatica gel, blend it well and apply onto the affected skin, twice a day.
4. Indigo naturalis ointment：Indigo naturalis is a traditional chinese herb that has been studied for its therapeutic effects on psoriasis. Mix Indigo Naturalis powder with petroleum jelly, apply onto the affected areas, twice daily.
但请注意，牛皮癣草药外洗方并非适用于所有人，不能完全治愈牛皮癣，也不应成为唯一的治疗方式。在使用草药治疗之前，请确保咨询医生，总结您的状况和治疗计划，并与常规诊疗结合使用，共同达到缓解牛皮癣症状的目的。
