The side effects and dangers of Siwei San are not known. Four Reversible San is mainly used for fever and syncope of hands and feet without warmth, epigastric and abdominal rib pain, dysentery and heaviness. It is composed of Citrus aurantium, Radix Bupleurum Chinense, Radix et Rhizoma Glycyrrhizae Praeparatae, Radix Paeoniae Lactiflorae, and has the effect of regulating the spleen and dispersing the liver, and relieving depression by penetrating the evil spirits. It mainly treats the syndrome of yang depression and syncope (the poor functioning of yang qi leading to cold extremities), which is characterized by the lack of warmth of the hands and feet or abdominal pain, or the failure of stools to be shaped with a stringy pulse. It also treats the syndrome of Liver-Spleen disharmony (inability of the liver and spleen to work in harmony), which is characterized by pain in the epigastrium (abdomen) and distension and pain in the ribs and thighs. In this formula, Chai Hu dredges the liver and resolves depression (treating depression by dredging the liver’s qi), allowing the evil to go out; Citrus aurantium ejaculates heat and breaks up knots, regulating qi and resolving depression; Paeonia lactiflora softens the liver and nourishes the blood; and Glycyrrhiza glabra harmonizes all the medicines (regulating the medicinal properties of different Chinese medicines) to benefit the spleen and harmonize the middle. The combination of the four herbs is effective in dispersing the liver and regulating the spleen by dispersing heat and relieving depression. Contraindications and side effects of this product are not clear, please do not use the drug by yourself, if you feel unwell, please go to the hospital.