The pain in the left side of the throat may be due to diseases such as left peritonsillar abscess, left-sided throat ulcer, acute pharyngitis, and left-sided throat tumor. 1. Left peritonsillar abscess: purulent inflammation in the interstitial space around the tonsils. In the early stage, it is peritonsillitis, followed by abscess formation. Patients often have fever, increased pain in the left side of the throat, especially when swallowing, and the pain often radiates to the ear and teeth on the same side. 2. Left pharyngeal ulcers: left pharyngeal mucosal ulcers can lead to left-sided throat pain. 3. Acute pharyngitis: usually due to bacterial infection, viral infection, overuse of voice, allergic reaction and other conditions, and also related to fatigue, cold and other factors. Patients often have a sore throat, hoarse voice, cough and other symptoms, but also the phenomenon of the left side of the throat pain. Some patients can also be accompanied by cold, headache, loss of appetite and other systemic symptoms. 4. Left pharyngeal tumor: common left hypopharyngeal cancer, left laryngeal cancer and other diseases can lead to left side throat pain. It is suggested that when patients have the symptom of left side throat pain, they should consult the hospital for diagnosis and treatment.