Dar Yuan Drink is mainly applied to damp-heat diseases caused by plague, filth and toxicity. Damp-heat diseases usually have a long course, and Dar Yuan Drink has certain therapeutic effects. The main ingredients of Dar Yuan Drink include betel nut, Hou Pu, Zhi Mu, Paeoniae Alba, Scutellariae Radix, Caulis Fructus, Glycyrrhiza Uralensis and so on. It is commonly used in the treatment of malaria, influenza and viral encephalitis, in which warm-heat and epidemic toxins are present in the membranous origin. When dampness-heat is suppressed, additions and subtractions can be made through this formula. Drugs that clear heat and dry dampness (removing heat and drying dampness) can be added, and Huang Lian can be added if the heart is heavy with fire, Gentian Herb can be added if the liver is heavy with fire, Huang Bai can be added if there is yin deficiency, and Scutellaria Baicalensis can be added appropriately for the lung is heavy with fire. For patients with internal damp-heat manifesting a series of symptoms of evil ambush in Shaoyang and Yangming, the disease is lingering, and the course of the disease is generally long, repetitive and difficult to get well quickly, so the use of Chai Hu and Pueraria Mirifica can be added on top of this formula to achieve the effect of clearing up and resolving the epidermis and removing filth and drying up dampness. Damp-heat patients who are not feeling well, need to be under the guidance of a traditional Chinese medicine practitioner according to their own situation to identify the use of medication.