Angelica Sinensis Four Reversal Soup has the effect of warming the meridians and dispersing cold, nourishing the blood and opening the veins. The term Si-wei refers to the lack of warmth in the extremities. This formula mainly treats Blood deficiency, cold extremities, pale tongue with white fur and thin pulse. The extremities are the basis of all yang. Blood deficiency with cold causes the extremities to lose yang temperature, so the extremities are cold. However, there are also other signs of coldness in the internal organs, such as diarrhea and abdominal pain, which indicate blood deficiency and coldness in the meridians, not yang deficiency in the internal organs. Therefore, the treatment is to nourish the Blood and open the channels, not to warm the internal organs. In the formula, Gui Zhi and Bai Shao nourish Blood and open the meridians to treat cold extremities, and Hosin can strengthen the effect of opening the meridians, which is a complementary drug. Moutong is cold in nature and can prevent overheating of warming drugs in the formula. This formula is designed for Blood deficiency and coldness, and red and dry tongue is prohibited.