Sudden parotid gland enlargement without pain in adults may be caused by IgG4-related salivary gland inflammation, and the treatment is mainly immunomodulatory therapy with glucocorticoids combined with immunosuppressants, as follows. IgG4-related salivary gland inflammation is mostly seen in middle-aged and old people, and there are no obvious self-conscious symptoms except for enlarged glands. Glucocorticosteroids, such as prednisolone, dexamethasone, etc., combined with immunosuppressants, such as azathioprine, methotrexate, etc., can be used to carry out comprehensive immunomodulation, which can reduce the serum IgG4 level, control the enlargement of the parotid gland, and improve the secretion function of the salivary gland. The above drugs need to be used under the guidance of a doctor, it is recommended to go to the hospital in a timely manner, with the help of the doctor for targeted treatment.