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Melasma: Causes

Melasma often begins during pregnancy

Levels of the hormones increase during pregnancy, and this increase is believed to trigger melasma in some people.

Happy husband caressing the belly of his smiling pregnant wife

What causes melasma?

More research is needed to fully answer this question. Researchers have discovered that when someone has melasma, the cells that give skin its color (melanocytes) tend to be more active. Exactly why this happens isn’t well understood.

It may be that melasma develops when something triggers these skin cells, causing them to go into overdrive.

The list of possible melasma triggers includes:

Sunlight: When sunlight hits our skin, it triggers the body to produce more melanin. This seems to explain why melasma develops on skin that gets the most sunlight like skin on the face, neck, and arms.

Pregnancy: An increase in the hormones estrogen and progesterone, which occurs during pregnancy, is thought to trigger melasma.

Some medications: The following medications may trigger melasma in some people:

  • Anti-seizure medications

  • Birth control pills (also known as oral contraceptive pills)

  • Medications that make your skin more sensitive to sunlight (includes retinoids, some antibiotics, and some blood pressure medications)

Stress: While this is controversial, some research findings suggest that stress can trigger melasma. Stress causes the body to make more of the hormone cortisol. An increase in cortisol may trigger melasma.

Tanning beds: A tanning bed or sunlamp tends to produce stronger ultraviolet (UV) rays than sunlight. When you expose your skin to UV light, it triggers the body to produce more pigment. Sometimes, this pigment appears unevenly, causing the blotchy patches and freckle-like spots of melasma.

Thyroid disease: Your thyroid is a gland located in your neck. It makes hormones that help your body with important jobs, including breaking down food you’ve eaten and regulating how fast your heart beats. If your thyroid gland develops a problem, this may increase your risk of developing melasma. Sometimes, treating the thyroid problem clears up the melasma.

Some people have a greater risk of developing melasma

Why a trigger causes melasma in some people but not others isn’t entirely clear. We do know that some people have a higher risk of developing melasma. You have a greater risk if you:

  • Are a woman between the ages of 20 and 40: Melasma is much more common in women than men. Hormones seem to play a role in causing melasma.

  • Have a medium or dark skin tone: Melasma develops more frequently in these skin tones than in lighter skin tones. You’re more likely to develop melasma if you are a woman of Latin, Asian, Black, or Native American heritage.

  • Have a blood relative who has melasma: Several studies have found that patients with melasma often have one or more blood relative(s) who also had melasma.

    In one study of 324 melasma patients around the globe, 48% reported that they have a blood relative with melasma. Other studies have reported similar numbers.

If something is triggering melasma, it may clear on its own. This often happens after a person gives birth or stops taking a medication that triggers the melasma.

Sometimes, melasma stays around for years. If melasma bothers you, a dermatologist can talk with you about treatment options. Many treatment advances have been made in recent years.

You’ll find what a treatment plan may include at: Melasma: Diagnosis and treatment.

Getty Images

Chaowattanapanit S, Silpa-Archa N, et al. “Postinflammatory hyperpigmentation: A comprehensive overview: Treatment options and prevention.” J Am Acad Dermatol. 2017 Oct;77:607-21.

Ogbechie-Godec OA, Elbuluk N. “Melasma: An up-to-date comprehensive review.” Dermatol Ther (Heidelb). 2017;7(3):305-18.

Pandya AG, Rivas S, “Melasma.” In: Taylor and Kelly’s Dermatology for Skin of Color. (second edition). McGraw Hill, USA, 2016:356-9.

Sheth VM, Pandya AG. “Melasma: A comprehensive update. Part 1” J Am Acad Dermatol. 2011;65:689-97.

Written by:
Paula Ludmann, MS

Reviewed by:
Arturo Dominquez, MD, FAAD
Ivy Lee, MD, FAAD

Last updated: 2/15/22