The symptoms of painful swallowing on the left side of the throat are often caused by acute inflammation of the left pharynx. Acute congestion and swelling of the mucous membrane on the left side of the throat. In addition, there may be congestion and swelling of the tonsils on the left side, or even purulent infection, which may cause the symptoms of painful swallowing of saliva in the left side of the throat. Some patients may further develop local complications such as peri-tonsillitis or peri-tonsillar abscess on the left side, and the symptoms of sore throat are often more intense, even making it difficult to swallow normally and eat.