Swelling on the outside of the ear is considered to be related to insect bite dermatitis, allergic skin diseases, auricular suppurative chondritis, boils and so on. 1. Insect bite dermatitis: when the patient’s skin outside the ear is bitten by mosquitoes, it may cause insect bite dermatitis. The skin lesions are characterized by fusiform bright red wind-bubble-like damage and are accompanied by skin redness, erythema, blisters, etc., thus manifesting as swelling outside the ear. 2. Allergic dermatosis: Allergic dermatosis is mainly related to contact, injection, inhalation of allergic substances, and swelling outside the ear is considered to be related to contact with animal fur, chemicals and so on. Allergic dermatosis may cause itching, stinging, redness and swelling of the skin in some patients, and may be accompanied by other conditions such as pimples and scales, which may also be manifested as swelling outside of the ear. 3. Auricular septic chondritis: Auricular septic chondritis is related to the spread of infection in the outer ear and neighboring tissues, as well as ear trauma and pressure injuries. Typical symptoms of patients include local skin redness, swelling, burning sensation, pain, etc., which are easily accompanied by other symptoms such as elevated body temperature, local skin elevation, pus discharge, etc., and some patients may show that the outside of the ear is swollen. 4. Boils: Boils can also cause swelling outside the ear in some patients, mainly related to pathogen stimulation or damage to local tissues. Boils are mainly caused by Staphylococcus aureus infections, and in addition to localized skin swelling, they may be accompanied by other symptoms such as skin redness, elevated temperature, pain, and localized lymph node enlargement. It is recommended that people with swollen ears should consult a doctor for examination and treatment after clarifying the cause of the disease. Strengthen daily skin care, avoid foreign body friction stimulation.