Pigmentation is the coloring of a person's skin. When a person is healthy, his or her skin color will appear normal. In the case of illness or injury, the person's skin may change color, becoming darker (hyperpigmentation) or lighter (hypopigmentation).

Hyperpigmentation in skin is caused by an increase in melanin, the substance in the body that is responsible for color (pigment).

Hyperpigmentation can be caused by sun damage, inflammation, or other skin injuries, including those related to acne vulgaris. People with darker Asian, Mediterranean, or African skin tones are more prone to hyperpigmentation, especially with excess sun exposure.

Many forms of hyperpigmentation are caused by an excess production of melanin. Hyperpigmentation can be diffuse or focal, affecting such areas as the face and the back of the hands. Melanin is produced by melanocytes at the lower layer of the epidermis. Melanin is a class of pigment responsible for producing color in the body in places such as the eyes, skin, and hair. As the body ages, melanocyte distribution becomes less diffuse and its regulation less controlled by the body. UV light stimulates melanocyte activity, and where concentration of the cells is greater, hyperpigmentation occurs. Another form of hyperpigmentation is post inflammatory hyperpigmentation. These are dark and discolored spots that appear on the skin following acne that has healed.

Hyperpigmentation is associated with a number of diseases or conditions, including the following.

Treatment of hyperpigmentation may include hydroquinone, kojic acid, alpha hydroxy acids, azelaic acid, ascorbic acid, tretinoin (Retinol), topical glucocorticoids, and licorice extract. Sunscreen may help to prevent these dark spots