In general, mouth ulcers do not cause sore throat, may be caused by bad habits, or complication of acute pharyngitis, herpes pharyngitis and other diseases. 1. Bad habits: If the mouth ulcer patients use their voices excessively, or excessive smoking, drinking, eating spicy and stimulating food, to a certain extent, it will cause pharyngeal congestion and edema, and then appear the situation of sore throat. 2. Acute pharyngitis: this disease is caused by viral and bacterial infections, such as coxsackievirus, adenovirus, streptococcus, etc., which can be triggered by factors such as dry climate and decreased systemic resistance. If oral ulcer patients are complicated with acute pharyngitis, they will have sore throat, and also have dry and itchy pharynx. 3. Herpetic pharyngitis: this disease is mainly caused by viral infection, can be through the nasopharynx, oral invasion of the respiratory tract and the digestive tract mucosa caused by a series of inflammatory reactions, can be manifested as sore throat, cough, fever, etc., therefore, when oral ulcers complicate the herpetic pharyngitis will appear sore throat. It is recommended that patients with mouth ulcers and sore throats go to the hospital, complete the relevant examinations and identify the specific causes.