Common symptoms of allergic cheilitis include peeling of the lips, itching, redness and swelling of the lips, and skin flushing. In severe cases, blisters may form, and the lips can become eroded and exudative. Repeated scratching due to itchiness or repetitive mechanical friction can lead to infection. The infection is generally a secondary bacterial infection, causing pus formation in the affected skin areas. Allergic cheilitis is often caused by contact with irritating substances, such as irritant foods, lipstick, and toothpaste. Some individuals develop allergic cheilitis after exposure to sunlight, and the condition can worsen. Therefore, patients with allergic dermatitis must receive anti-allergy treatment.