Melasma (cont.)

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What causes melasma?

The exact cause of melasma remains unknown. Experts believe that the dark patches in melasma could be triggered by several factors, including pregnancy, birth control pills, hormone replacement therapy (HRT and progesterone), family history of melasma, race, antiseizure medications, and other medications that make the skin more prone to pigmentation after exposure to ultraviolet (UV) light. Uncontrolled sunlight exposure is considered the leading cause of melasma, especially in individuals with a genetic predisposition to this condition. Clinical studies have shown that individuals typically develop melasma in the summer months, when the sun is most intense. In the winter, the hyperpigmentation in melasma tends to be less visible or lighter. Heat, such as that experienced in a bakery or factory, is also thought to be a cause.

When melasma occurs during pregnancy, it is also called chloasma, or "the mask of pregnancy." Pregnant women experience increased estrogen, progesterone, and melanocyte-stimulating hormone (MSH) levels during the second and third trimesters of pregnancy. Melanocytes are the cells in the skin that deposit pigment. However, it is thought that pregnancy-related melasma is caused by the presence of increased levels of progesterone and not due to estrogen and MSH. Studies have shown that postmenopausal women who receive progesterone hormone replacement therapy are more likely to develop melasma. Postmenopausal women receiving estrogen alone seem less likely to develop melasma.

In addition, products or treatments that irritate the skin may cause an increase in melanin production and accelerate melasma symptoms.

People with a genetic predisposition or known family history of melasma are at an increased risk of developing melasma. Important prevention methods for these individuals include sun avoidance and application of extra sunblock to avoid stimulating pigment production. These individuals may also consider discussing their concerns with their doctor and avoiding birth control pills and hormone replacement therapy (HRT) if possible.

Medically Reviewed by a Doctor on 10/9/2013

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