Lip hyperpigmentation is a disorder in which the skin cells on and around the mouth begin to produce too much melanin, the primary pigment in human skin. This condition can occur due to changes in the body's hormonal balance, from inflammation around the mouth, after exposure to ultraviolet light, or because of a systemic disorder. For most people, lip and mouth hyperpigmentation is only a cosmetic problem, but dark lips can indicate a serious condition in some cases.
Focal hyperpigmentation occurs after a cut or burn in the mouth area, or after inflammation from lupus, acne, or other diseases. Some people suffer from this type of lip hyperpigmentation after eating plants that contain furocoumarin, a compound that can make the skin more sensitive to the sun. Often, focal hyperpigmentation decreases after a few months, and the skin may even return to normal.
Melasma is a kind of lip hyperpigmentation that forms sharp, dark brown, symmetrical patches on the face. In addition to the lips, melasma can also show up on the temples, cheeks, and forehead. Pregnant women and people taking oral contraceptives or other hormonal treatments are most likely to suffer from this problem. Dark-skinned people get melasma more often than light-skinned people. Sun exposure, drugs that increase sensitivity to the sun, and thyroid disorders can all trigger this condition.
Older people often get lentignes, also known as liver spots. Lentignes occur when the body suddenly produces more melanin in an area which has been exposed to the sun. These tan to dark brown spots appear on the hands, face, and head. They may overlap the lips in some cases, and are considered a risk factor for skin cancers like melanoma.
Some systemic disorders and drugs produce hyperpigmentation on the lips and other parts of the body. For instance, Laugier-Hunziker syndrome, or LHS, produces lines on the fingernails and dark spots on the lips. Addison's disease, an adrenal disorder, can cause bluish-black discoloration on the mouth, lips, nipples, and other sensitive areas. People taking anti-malarial drugs, large doses of hydroquinone, tetracycline, or drugs containing heavy metals may develop dark spots on the face and mouth.
Treatment for lip hyperpigmentation depends on the type. Dermal hyperpigmentation is permanent and untreatable, but excessive pigment build-up in the epidermis can be treated using hydroquinone, bleaching agents, or chemical peels. Some patients require laser or surgical procedures to remove the hyperpigmentation. When drugs or a systemic imbalance cause the problem, discontinuing medication or treating the imbalance may return the skin to normal.