Cleanse lips daily with cleansing milk. Occasionally brush your lips with a brush. This kills dead cells. To avoid the sun's ultraviolet rays, apply lip balm or coconut oil with SPF lipstick on it before going out in the sun. Before going to bed at night, you must remove the lipstick with cream or wet cotton and apply Vaseline. Or biting the lip is a very bad habit. It should be discarded. Lack of vitamin C causes chapped lips. For this, eat foods rich in vitamin C and consult a doctor.