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Sun, hormones can cause dark skin spots

Copyright 2002 President Fellows Harvard College behalf HMS MediServices Phoby LizGreen HMS MediServices Anthony Leader Komaroff MD Harvard Health Publications

Copyright 2002 President and Fellows of Harvard College on behalf of HMS Media Services, Photo by Liza Green, HMS Media Services, Anthony Leader Komaroff, MD, Harvard Health Publications

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Updated: July 23, 2012 6:38AM

Dear Doctor K: I’m a woman in my late 20s, and I’ve developed dark patches of skin on my face. Why did this happen? What can I do about it?

Dear Reader: It sounds like you could have melasma. This is a condition in which areas of skin become darker than the surrounding skin, typically on the face. The number of pigmented skin cells called melanocytes is higher in the darker areas of the skin. Why there are increased numbers of melanocytes in certain places and not others remains a mystery.

Melasma occurs more often in women than in men, and also occurs more often in women who have darker skin to begin with. It may be more common in people who have thyroid problems.

Sun exposure is a strong risk factor for melasma. Some cosmetics and medications can make you more sensitive to the sun and can increase your risk of developing melasma.

Melasma is often associated with hormonal changes. Dark patches often develop during pregnancy, or if a woman is taking hormone replacement therapy (HRT) or oral contraceptives.

If your melasma is hormone-based, then as your hormones stabilize, your dark patches should fade. If you are pregnant, your patches should fade or disappear after your baby is born. Women who take oral contraceptives or HRT typically see the patches fade or disappear gradually after they stop taking these medications.

The first thing you need to do is to protect your skin from the sun:

Wear a brimmed hat.

Apply sun block to vulnerable areas.

Use sunscreen with an SPF of 30 or more that protects against ultraviolet A and B rays.

In some cases, the discoloration doesn’t entirely disappear on its own. Try one of these “bleaching” treatments:

Hydroquinone cream blocks the creation of melanin, the substance that makes skin dark.

Tretinoin cream increases the rate at which dead skin cells fall off and new ones appear.

Azelaic acid cream slows down or stops the production of pigment, the substance that colors the skin.

Chemical peels are applied to the skin to provide a mild chemical burn. The burned layers peel off, leaving fresh, new skin.

Intense pulsed light therapy uses certain wavelengths of light to remove pigmented areas of skin. This treatment is not available in all communities, and it’s best to go to a doctor with extensive experience in using it.

If you are pregnant, talk to your doctor before trying any of these treatments. They may have side effects that could harm your unborn baby.

In my experience, melasma most often occurs during pregnancy and goes away after pregnancy. When it doesn’t go away completely, treatments usually are successful.

Write to Dr. Komaroff at

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