What causes cracked corners of the mouth?

Angular cheilitis, commonly known as cracked corners of the mouth, can arise from various causes: 1. Dry skin is one of the common factors, especially during autumn and winter when dry weather combined with insufficient water intake can lead to skin dehydration, causing chapped corners of the mouth and subsequent infection. 2. Poor nutrition is another significant cause, particularly deficiency in vitamin B2 (riboflavin), which impairs biological oxidation and metabolism in the body, leading to cracking and ulceration at the corners of the mouth. 3. The habit of frequently licking the lips can also contribute to angular cheilitis. Saliva quickly evaporates after licking, further drying out the lips and exacerbating inflammation. 4. Infections may also cause angular cheilitis, including viral infections (such as herpes simplex virus) and bacterial infections (such as Staphylococcus aureus). These infections can result in symptoms like swelling, pain, itching, and pus formation at the mouth corners. 5. Lifestyle factors such as stress, anxiety, excessive fatigue, and lack of sleep due to staying up late may also trigger angular cheilitis.