Radiation therapy is a common treatment modality in the management of head and neck malignancies. However, head and neck tumors often have some adverse reactions when receiving radiation therapy, such as dry mouth, change of taste, oral mucositis, etc. Among them, the incidence of oral mucositis is more than 90%, and the incidence of oral mucositis of degree 3 or more than degree 3 is more than 50%. Severe oral mucositis seriously affects the quality of survival of patients. Lactobacillus rhamnosus GG (LGG) is a type of lactic acid bacterium, which is an important component of the microbiota in many parts of the human body. Lactobacillus rhamnosus GG (LGG) is a lactic acid bacterium found in the human body, extensively researched for its probiotic properties. It has been tested in clinical trials for preventing and treating oral mucosal reactions during intensified radiotherapy for head and neck squamous cell carcinoma. LGG adheres well to epithelial layers, produces a protective biofilm, and modulates immune responses. It shows promise in reducing radiation-induced oral mucositis and can be safely used in infant formula. Additionally, a daily dosage of 3×10\^9 CFU of LGG has been effective in treating irritable bowel syndrome without adverse effects