Patchy areas of dark color appear on the skin.
Doctors usually base the diagnosis on an examination of the skin.
Treatment includes sun protection and skin-bleaching creams.
Melasma is most likely caused by an overproduction of the pigment melanin. Melanin is produced by specialized skin cells called melanocytes (see Overview of Skin Pigment Overview of Skin Pigment Melanin is the pigment that produces the various shades and colors of human skin, hair, and eyes. Coloration (pigmentation) is determined by the amount of melanin in the skin. Without melanin... read more 
).
Too much pigment in the skin is called hyperpigmentation Hyperpigmentation Hyperpigmentation is darkening of the skin, most often caused by an abnormally high amount of the skin pigment melanin. When exposed to sunlight, specialized skin cells called melanocytes (see... read more . Melasma tends to appear during pregnancy (called the mask of pregnancy Skin 
) and in women who take oral contraceptives Oral Contraceptives Contraceptive hormones can be Taken by mouth (oral contraceptives) Inserted into the vagina (vaginal rings) Applied to the skin (patch) Implanted under the skin read more 
, but it can occur in anyone. The disorder is most common among and lasts longer in people with dark skin. Ten percent of cases occur in women who are not pregnant and in dark-skinned men.
People who spend a lot of time in the sun are at increased risk of melasma. Other risk factors include autoimmune thyroid disorders and drugs that make some people's skin more sensitive to the effects of sunlight.
Symptoms of Melasma
Irregular, patchy areas of dark color appear on the skin, usually on both sides of the face. The pigmentation most often occurs in the center of the face and on the cheeks, forehead, temples, upper lip, and nose. Sometimes people have the patches only on the sides of the face. Rarely, melasma appears on the forearms. The patches do not itch or hurt and are only of cosmetic concern.
Diagnosis of Melasma
A doctor's evaluation
Wood light examination
Doctors base the diagnosis of melasma on an examination of the skin.
Doctors may do a Wood light Wood light (black light) Doctors can identify many skin disorders simply by looking at the skin. A full skin examination includes examination of the scalp, nails, and mucous membranes. Sometimes the doctor uses a hand-held... read more 
examination to differentiate hyperpigmentation in the epidermis (upper layers of the skin) from other skin disorders.
Treatment of Melasma
Skin-bleaching creams
Sometimes chemical peels or laser treatments
Sun protection
Treatments applied to the skin are effective only if hyperpigmentation affects the upper layers of the skin. Skin-bleaching creams containing hydroquinone, tretinoin, or a corticosteroid can be used in combination to help lighten the dark patches. However, hydroquinone should be used only under the guidance of a doctor, because long-term use can sometimes cause a permanent form of hyperpigmentation. A cream containing azelaic acid can be used in place of or combined with hydroquinone, tretinoin, or both.
Doctors may try chemical peels with glycolic acid or trichloroacetic acid on people who do not respond to skin-bleaching creams.
During pregnancy, azelaic acid cream and chemical peels with glycolic acid are safe to use. Hydroquinone and tretinoin are not safe to use.
Laser treatments and tranexamic acid, which is a drug taken by mouth, are also used.
During and after treatment, people must be strict about sun protection because treatments make the skin prone to sunburn. Also, even a few hours of sun exposure can cause hyperpigmentation to begin again in the treated areas, which would undo the results of months of treatment.
People with melasma should use sunscreens Sunscreens Sunburn results from a brief (acute) overexposure to ultraviolet (UV) light. Overexposure to ultraviolet light causes sunburn. Sunburn causes painful reddened skin and sometimes blisters, fever... read more 
with a sun protection factor (SPF) of 30 or higher, wear protective clothing Clothing Sunburn results from a brief (acute) overexposure to ultraviolet (UV) light. Overexposure to ultraviolet light causes sunburn. Sunburn causes painful reddened skin and sometimes blisters, fever... read more , and avoid sun exposure Avoidance Sunburn results from a brief (acute) overexposure to ultraviolet (UV) light. Overexposure to ultraviolet light causes sunburn. Sunburn causes painful reddened skin and sometimes blisters, fever... read more to prevent the condition from getting worse. Most chemical sunscreens protect the skin from ultraviolet light but not from visible light. People should use a tinted sunscreen that also contains zinc oxide or titanium dioxide, which are natural minerals that provide a physical block against visible light. For greater protection, people can use a sunscreen that contains both minerals and antioxidants. For even more protection, people can take the dietary supplement Polypodium leucotomos by mouth.
If the skin is protected from the sun, melasma often fades after pregnancy or after an oral contraceptive is stopped. In men, melasma rarely fades.
