Hyperpigmentation is usually caused by sun damage, inflammation, or other skin injuries, including those related to acne vulgaris and hormonal changes such as those experienced during pregnancy. People with darker Asian, Mediterranean, or African skin tones are also more prone to hyperpigmentation, especially if they have 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 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 concentrations of the cells are denser than surrounding areas, hyperpigmentation is effected. Can also be caused by using skin lightening lotions. Another form of hyperpigmentation is post inflammatory hyperpigmentation. These are dark and discolored spots that appear on the skin following acne that has healed.