Chai Hu, Gui Zhi, Gan Jiang Tang is a prescription from the Treatise on Typhoid Fever, consisting of 24 grams of Chai Hu, 9 grams of Gui Zhi, 9 grams of Gan Jiang, 12 grams of Psidium guajava, 9 grams of Scutellaria baicalensis, 6 grams of oyster, and 6 grams of Glycyrrhiza glabra. In this formula, Chai Hu and Scutellaria baicalensis are used to clear away heat; Psidium guajava root and oyster are used to open the knot; Gui Zhi and Gan Jiang are used to promote Yang and disperse cold, warming water-dampness; and Glycyrrhiza glabra is used to harmonize all the medicines (harmonize the properties of different Chinese medicines). This formula combines heat and cold, attacking and tonifying, which can not only drain and relieve depression, but also warm and transform water-dampness. This formula can be used to treat typhoid fever and Shaoyang disease with internal accumulation of water-dampness, manifesting as: fever alternating with malignant cold (fear of cold), malignant cold is heavy and fever is light, distension and fullness of the chest or ribs, dysuria, thirst without vomiting, only sweating, and feeling upset; malaria patients have more malignant cold and less fever, or malignant cold but no fever. Clinical application of this formula should be carried out safely under the guidance of a physician.