Sore throat on the left side may be caused by foreign body injury, tonsillar inflammation, acute pharyngitis, pharyngeal tumors and so on. 1. Foreign body injury: when the left side of the throat is injured by fish splinters and other sharp objects, the left side of the throat will be sore. 2. Inflammation of tonsil: unilateral inflammation of tonsil can be caused by bacterial or viral infection, or induced by cold, weak resistance, stimulation of tobacco and alcohol. The main symptoms are sore throat, swallowing pain, dysphagia, dyspnea, unilateral throat pain, and systemic symptoms can be accompanied by fever and malaise in severe cases. 3. Acute pharyngitis: acute pharyngitis refers to the pharyngeal mucosa, often secondary to acute rhinitis or acute tonsillitis. The main symptom is sore throat, which can be manifested as unilateral pain slightly obvious phenomenon, often accompanied by dry pharynx, itchy pharynx and foreign body sensation in the throat and other discomforts. 4. Pharyngeal tumor: When there is a tumor in the left side of the throat, it can compress the surrounding tissues and cause left side sore throat, as well as foreign body sensation in the throat, blood in sputum and other symptoms. If you have left side sore throat, it is recommended to consult a doctor for a clear diagnosis.