The left side of the throat is considered to be related to acute tonsillitis, pharyngitis, laryngeal cancer and so on. 1. Acute tonsillitis: Acute tonsillitis is related to bacterial infection, viral infection, etc. Excessive smoking and alcohol, decreased immunity are the triggering factors. Typical symptoms of patients include sore throat, chills, fever, loss of appetite, fatigue, enlarged local lymph nodes, etc., which may be accompanied by pain on the left side of the throat. 2. Isthmus: Isthmus is mainly caused by bacterial, viral and other pathogen infections, malnutrition, oral uncleanliness and other triggering factors. The disease can cause some patients to have pain on the left side of the throat, and it is also easy to be accompanied by other symptoms such as sore throat, dry throat, salivation, decreased appetite and so on. 3. Laryngeal cancer: the cause of the disease is still unclear, it may be related to the change of sex hormone level, viral infection and so on. When there is cancer on the left side of the throat, it can be manifested as pain on the left side of the throat. Patients with laryngeal cancer are also prone to other symptoms such as hoarseness, foreign body sensation in the throat and blood in sputum. Patients are advised to seek medical examination immediately so that they can follow the doctor’s prescription after a clear diagnosis.