What causes redness at the corners of the mouth?

    Under normal circumstances, redness at the corners of the mouth may be caused by food irritation, dry environment, contact dermatitis, angular cheilitis, or cold sores. The solution depends on the specific cause and medical consultation should be sought promptly for treatment as directed by a physician. Details are as follows:

    1. Food irritation: Consuming excessive spicy or irritating foods, such as chili peppers, hot pot, or spicy noodles, may cause the spicy ingredients to irritate the lips, leading to local vasodilation and increased blood circulation, resulting in redness at the corners of the mouth. No special treatment is required, and symptoms can be improved by adjusting the diet. Spicy foods should be reduced, more water should be consumed, and symptoms will gradually improve after a period of rest.

    2. Dry environment: In a dry environment, if the skin around the lips is not adequately moisturized, the skin at the corners of the mouth may become dry and cracked due to dehydration, leading to redness. Indoor temperature and humidity should be properly regulated, and a humidifier can be used to increase indoor humidity. Additionally, skin hydration should be maintained by applying moisturizing lip balm or skincare products.

    3. Contact dermatitis: When the corners of the mouth come into contact with allergens such as cosmetics, food residue, or metal jewelry, an allergic reaction may occur, causing contact dermatitis and resulting in redness at the corners of the mouth. Treatment should follow a physician's guidance using medications such as mupirocin ointment, clobetasol propionate cream, or prednisolone acetate cream.

    4. Angular cheilitis: Angular cheilitis may be related to vitamin deficiency or bacterial infection. Inflammatory factors invade and irritate the skin at the corners of the mouth, causing symptoms such as redness, swelling, congestion, and cracking, which may be accompanied by erosion. Treatment should follow a physician's instructions using anti-infective medications such as cefixime granules, amoxicillin capsules, or erythromycin ointment.

    5. Cold sores: Cold sores are caused by infection with the herpes simplex virus. When the virus affects the corners of the mouth, symptoms such as redness, swelling, and erosion may occur, which may also be accompanied by fatigue. Antiviral medications such as acyclovir ointment, famciclovir dispersible tablets, or ribavirin capsules should be used as directed by a physician.

    Maintain cleanliness and dryness at the corners of the mouth in daily life, avoid scratching or washing with hot water to prevent secondary infection.

    References:

    [1] Zhang Zhiyuan. Oral and Maxillofacial Surgery [M]. 8th edition. Beijing: People's Medical Publishing House, 2017.

    [2] Zhang Xuejun. Dermatology and Venereology [M]. 9th edition. Beijing: People's Medical Publishing House, 2018.