Swelling of the mouth for no reason may be related to lipitis, angioneurotic edema, mosquito bites and other causes. 1. Lipitis: often caused by chronic irritation, taking or contacting allergic substances and other factors, there may be lip pain, swelling, oozing, erosion and other symptoms. 2. Angioneurotic edema: acute limited edema of the dermis, subcutaneous tissue, mucosa and other subcutaneous loose tissues due to allergies and other factors, when consuming allergenic substances such as mango, swelling of the mouth can occur for no apparent reason. 3. mosquito bites: mosquito bites mouth can release saliva into the body, which can be used as antigenic substances to cause the body to abnormal immune response, the phenomenon of mouth swelling for no reason. It is recommended that people with swollen mouths for no reason go to the hospital in a timely manner, to clarify the cause of the disease, under the guidance of the doctor for standardized treatment.