Multiple myeloma is a malignant hematological disease that easily occurs in the elderly. Patients with poor immune function after the onset of the disease are prone to various infections, such as lung infections or pneumonia, urinary tract infections, herpes zoster and other infections, as well as gastrointestinal infections that cause diarrhea, etc. Patients with diarrhea should have routine stool tests to determine if the diarrhea is infectious. Treatment plan. However, it is correct to give drugs such as Flavopiridol and Simethicone to control diarrhea first. Subsequently, the treatment should be adjusted according to the medication history and laboratory results. If the diarrhea is infectious, anti-infective treatment should be intensified. If there is no evidence of infection and the reaction is due to the use of Vanco, strong antidiarrheal drugs such as Emmenagogue should be added under the guidance of the doctor in charge (the treatment should not be too long).