Swelling: An allergic reaction can make the lips swell. The reaction may be caused by sensitivity to certain foods or beverages, drugs, lipstick, or airborne irritants. When a cause can be identified and then eliminated, the lips usually return to normal. But frequently, the cause of the swelling remains a mystery. A condition called hereditary angioedema may cause recurring bouts of swelling. Nonhereditary conditions—such as erythema multiforme, sunburn, cold and dry weather, or trauma—may also cause the lips to swell.

Treatment depends on the cause. A corticosteroid ointment is sometimes used to reduce swelling caused by an allergic reaction. Occasionally, excess lip tissue may be removed surgically to improve appearance.

Inflammation: With inflammation of the lips (cheilitis), the corners of the mouth may become painful, irritated, red, cracked, and scaly. Cheilitis may result from a deficiency of vitamin B₂ in the diet, but this deficiency is rare in the United States and can be treated by taking supplements of this vitamin.

Most commonly, skinfolds and irritated skin (angular cheilitis) may develop in the corners of the mouth if a person has dentures that do not separate the jaws adequately. Treatment consists of replacing the dentures, which helps reduce the folds at the corners of the mouth.

Discoloration: Freckles and irregularly shaped brownish areas (melanotic macules) are common around the lips and may last for many years. These marks are not cause for concern. Multiple, small, scattered brownish black spots may be a sign of a hereditary disease called Peutz-Jeghers syndrome, in which polyps form in the stomach and intestines (see Tumors of the Digestive System: Hereditary conditions). Kawasaki disease, a disease of unknown cause that usually occurs in infants and children 8 years old or younger, can cause dryness and cracking of the lips and reddening of the lining of the mouth (see Miscellaneous Disorders in Infants and Young Children: Kawasaki Disease).

Sores: A raised area or a sore with hard edges on the lip may be a form of skin cancer (see see Mouth Growths: Types of Oral Cancer and see Skin Cancers). Other sores may develop as symptoms of other medical conditions, such as oral herpes simplex virus infection (cold sores—see see Viral Infections: Herpes Simplex Virus Infections) or syphilis (see see Mouth Sores: Infection). Still others, such as keratoacanthoma, have no known cause.

Sun Damage: Sun damage may make the lips, especially the lower lip, hard and dry. Red speckles or a white filmy look signal damage that increases the chance of subsequent cancer. This type of damage can be reduced by covering the lips with a lip balm containing sunscreen or by shielding the face from the sun's harmful rays with a wide-brimmed hat.

Last full review/revision October 2006 by Robert B. Cohen, DMD