Huo Xiang Zheng Qi San is a formula for dispelling dampness. The main ingredients include Dahurian Pi, Angelica Dahurica, Ziziphi, Poria, Sempervivum, Atractylodes Macrocephalae, Pericarpium Citri Reticulatae, Hou Pu, Radix Platycodon, Huo Xiang and Licorice. The main function is to relieve dampness, regulate qi and harmonize the middle, so it mainly treats external wind-cold and internal dampness. In summer, it is a common symptom because the weather is hot and it is easy to crave cold and drink cold, so it is easy to cause vomiting and diarrhea or fullness in the chest and diaphragm and pain in the abdomen due to external wind-cold and internal dampness stagnation, as well as symptoms such as vicious cold, fever, headache and body pain due to wind-cold binding the surface. Therefore, Huo Xiang Zheng Qi San can be applied to relieve dampness, regulate Qi and harmonize the middle, which is commonly used in modern times to treat acute gastroenteritis.