What Causes Melasma?

I've always known that the women in my family have a tendency to get darkened patches of skin on certain areas of the body. My sister first developed them during puberty, and I experienced them during pregnancy. One of my more distant relative has had persistent dark patches for nearly a decade. This common condition, known as melasma, almost exclusively affects women. Those of us who have dealt with the condition and its effects are often left wondering: what, exactly, causes melasma?

Here are some of the potential causes and contributing factors.

Melanocyte Activity

With the exception of people with albinism, all individuals have specialized skin cells known as melanocytes. These produce pigment known as melanin, which is responsible for naturally dark skin tones and for tanning. The core cause of melasma is an overactivity of melanocytes, causing them to produce too much pigment and to distribute it unevenly.

Genetics and Ethnicity

A tendency to develop melasma often runs in families. It is most common among people with medium to dark skin tones, since they tend to have more melanocytes to begin with. People of African, Central American, South American, Native American, Southeast Asian, Middle-Eastern, and Mediterranean descent are the most likely to develop melasma.

Pregnancy

During pregnancy, hormonal changes stimulate an increase in the production and activity of melanocytes. This is why most women develop darkening of the areola and a dark line on the abdomen during pregnancy. In expectant mothers, melasma is known as "chloasma." It tends to resolve a no later than a few months after childbirth.

Contraceptives

The same hormones that cause melasma during pregnancy-- estrogen and progesterone-- are also used in hormonal contraceptives, including the Pill, the patch, the Depo Shot, and Nuvaring. Because of this, contraceptives can mimic some of the effects of pregnancy, including the development of melasma. If your melasma is severe, you may need to switch to a non-hormonal or low-hormone form of birth control.

Sun Exposure
Exposure to ultraviolet rays, whether through sunlight or tanning lamps, causes reactions from melanocytes. This puts women at much greater risk of developing melasma. When melasma has temporarily faded or vanished, it is likely to return after extended exposure to sunlight. The consistent and correct use of sunscreen can help to minimize the effects of melasma, while also protecting against skin cancer and sunburn-- so use it often.

If you are experiencing persistent melasma that isn't associated with any of the more common causes of the condition, get in touch with your primary health care provider. She can evaluate for signs of hormonal imbalances that might be contributing to the problem. If necessary, a referral to a dermatologist may help you find options for treatment and prevention.