Sudden enlargement of the jaw, generally refers to the enlargement of the soft tissues in the jaw area, and is considered to be a symptom caused by trauma, inflammation of soft tissues, periodontitis or allergic reaction. 1. Trauma: If the jaw is hit by external force and there is local soft tissue damage, such as soft tissue edema, the jaw will suddenly swell. 2. Inflammation of soft tissues: If the soft tissues of the jaw are infected, it may cause inflammation, which is commonly seen in folliculitis, acne, and inflammation of soft tissues around the jaw, etc., which may lead to sudden enlargement of the jaw. 3. Periodontitis: If periodontitis is caused by lack of attention to oral hygiene or bacterial infection, it may lead to tooth pain, gum swelling, etc., which may also lead to sudden swelling of the jaw. 4. Allergic reaction: If you are bitten by mosquitoes or contacted with allergens, which cause allergic reaction in the soft tissues of the jaw, it can also lead to sudden swelling of the jaw. If the jaw suddenly swollen, it is recommended to go to the regular hospital as soon as possible to find out the cause and take timely treatment measures.