Swallowing saliva, the left side of the throat hurts. Common diseases include: a. left peri-tonsillitis or peri-tonsillar abscess, which mainly occurs in the inflammatory infection of the peri-tonsillar space, mostly manifests as unilateral sore throat of the patient, the pain increases when swallowing, local abscess formation, there will be restricted mouth opening and other clinical manifestations, anti-inflammatory treatment is needed, if necessary, the application of hormone therapy, local abscess formation, abscess incision and drainage treatment is needed. Second, ulcers of the tonsils or ulcers of the anterior arch or lateral wall of the pharynx are manifested as obvious local pain when the patient swallows. The pain will be gradually relieved after the ulcer heals. Third, left-sided glossopharyngeal neuralgia, manifested as pain in the distribution area of the glossopharyngeal nerve, especially when the patient induces the trigger point when swallowing, the pain will be more obvious. Fourth, cancerous lesions of tonsils or hypopharyngeal carcinoma lesions, once the main body of cancer ruptures when the patient swallows, painful swallowing will occur, and drug treatment is ineffective.