Basia Wirkus from Poland asked this question. And here is Dr. Carsten Lekutat’s answer.
Dr. Lekutat‘s answer:
In the winter, many people suffer from dry skin, chapped lips, and even small cracks in the corner of the mouth. The unpleasant sensation often makes people lick their lips, but that actually makes it worse. Instead it’s best to try to keep the lips dry. That means you should avoid getting toothpaste on your lips and using irritating cosmetic and skin care products. You can apply a zinc salve to the sore spots on the corners of your lips, which will promote healing. But pay a visit to your doctor if the cracks don’t heal on their own. Sometimes illnesses and vitamin deficiencies can contribute to cracks in the corner of the lips.