Remember this one? “All whole numbers are integers, but not all integers are whole numbers.” Believe it or not, this math class gem is the perfect way to understand the difference between two related-but-not-completely skin conditions: melasma and hyperpigmentation. (Write your grade school math teacher and thank them for the skin care lesson!) 

Hyperpigmentation refers to any discoloration of the skin — be it an acne scar, sun damage, freckles, age spots, or a condition like melasma. Melasma is a type of hyperpigmentation, but it typically stems from different causes, which means we have to treat it a little differently. Put another way: All melasma is hyperpigmentation, but not all hyperpigmentation is melasma. Unfortunately, it can be tricky to differentiate between regular ol’ hyperpigmentation and melasma because they essentially present the same way. 

To demystify this tricky skin condition, we spoke to four dermatologists about the differences between melasma and hyperpigmentation, what causes them, and how to treat both.

Meet the Experts:

• Dhaval Bhanusali, MD, is a board-certified dermatologist based in New York City.
• Michele Farber, MD, is a board-certified dermatologist with the Schweiger Dermatologist Group in Philadelphia.
• Anthony Rossi, MD, is board-certified dermatologist and Mohs surgeon at Memorial Sloan Kettering in New York City.
• Adam Friedman is an associate professor of dermatology at George Washington University Medical Faculty Associates in Washington, D.C.

What is Hyperpigmentation?

“Hyperpigmentation is any darkening in skin pigment due to an increase in melanin,” says Philadelphia-based dermatologist Michele Farber. “This can be from inflammatory conditions like acne or eczema, injury to the skin, hormonal conditions, medications, and sunlight.”

This is because acne, sunlight, and skin rashes have the potential to stimulate melanocytes — the pigment-making cells in the skin — to make a surplus of pigment. This then causes the melanocytes to “dump their pigment into lower levels of the skin, like tattoo pigment, where it doesn’t belong,” explains Adam Friedman, an associate professor of dermatology at George Washington University Medical Faculty Associates in Washington, D.C. This results in discoloration of the skin, in what appears to be patches or freckles. 

Hyperpigmentation Causes

Post-blemish scarring from a stubborn breakout, freckles that expanded into full-blown sun spots from excess exposure, or discoloration caused by a condition like eczema or psoriasis usually all fall under the umbrella of hyperpigmentation.

What is Melasma?

Melasma is a common skin condition in which the body overproduces melanin, creating dark brown patches of pigment — typically on the face, forehead, upper cheeks, and around the mouth. This discoloration is also known as hyperpigmentation. Remember: All melasma is hyperpigmentation, but not all hyperpigmentation is melasma.

Melasma Causes

Melasma can be triggered by a number of external factors like sun exposure, heat, or skin trauma. It can even be genetic. But the real culprits here are hormones. Melasma mostly affects women — and is sometimes referred to as “the mask of pregnancy,” as it frequently appears during pregnancy due to the vast hormonal changes. It can also be triggered by birth control or hormonal therapies.

Melasma and Hyperpigmentation: How to Tell the Difference

It can be difficult to tell the difference between melasma and regular hyperpigmentation because they both appear as dark patches of pigment. But there are a few clues to help you suss out the difference.