Hyperpigmentation: What It Is, Why It Happens, and the Different Forms
By Melissa Pelletier, Licensed Esthetician | MP Skin Therapy at Wish Electrolysis and Laser Center, Fitchburg, MA
If you've ever noticed dark patches, uneven skin tone, or stubborn spots that seem to linger no matter what you try, you're not alone. Hyperpigmentation is one of the most common skin concerns I see as an esthetician (and I experience it personally)— and one of the most misunderstood.
In this first post of a two-part series, I want to break down exactly what hyperpigmentation is, why it happens, and the different forms it takes. My goal, as always, is to give you the why behind everything — because when you understand your skin, you're empowered to care for it in a way that actually works.
What Is Hyperpigmentation?
Hyperpigmentation is a skin condition characterized by an overproduction of melanin — the pigment responsible for the color of your skin, hair, and eyes. It shows up as patches or spots that are darker than your surrounding skin tone, and it can appear anywhere on the face or body.
Here's something that surprises a lot of people: we all have the same number of melanocyte cells — the cells that produce melanin — regardless of whether we have very fair or very dark skin. The difference lies in how much melanin those cells produce. Darker skin tones naturally produce more melanin, which also means they can be more prone to certain pigmentation disorders.
About 50% of the melanocytes in your entire body are located on the face and décolleté. This is exactly why these areas are so vulnerable to pigmentation changes, and why protecting and caring for the skin in these zones matters so much.
How Melanin Is Made — And Why It Misfires
To understand hyperpigmentation, it helps to understand how melanin is made in the first place.
Inside each melanocyte cell are structures called melanosomes — think of them as the Amazon delivery trucks for your skin. The melanocyte cell is the factory that makes the melanin. The melanosomes are the trucks that carry that melanin up through the layers of the skin to give you your complexion. When this process is working smoothly, the result is even, balanced skin tone.
The key player in melanin production is an enzyme called tyrosinase — a copper enzyme that triggers the chemical reaction that creates melanin. It does this by oxidizing tyrosine, an amino acid, which then becomes melanin. This process happens in the basal layer — the deepest layer of the epidermis — and the pigment travels upward through the layers of skin over time.
When this system works as it should, it's actually remarkable. Melanin exists to protect you. When your skin is exposed to some form of inflammation or injury such as UV rays, your immune system responds by signaling melanocytes to produce more melanin to shield your cells and DNA from damage. A tan is not a sign of health — it's your skin's distress signal. It's your body's way of telling you it needed more protection than it had.
The problem arises when this system misfires — when inflammation, hormones, UV exposure, or other triggers cause the melanocytes to overproduce melanin, deposit it unevenly, or continue producing excess pigment long after the trigger is gone. That is hyperpigmentation.
What Triggers Hyperpigmentation?
Hyperpigmentation has both external (extrinsic) and internal (intrinsic) causes. Often it is a combination of both.
External Triggers
UV and sun exposure — UVA and UVB rays are the most common trigger. Every time unprotected skin is exposed to the sun, the immune response stimulates melanin production.
Heat — Hot showers, saunas, and exercise can all stimulate pigment production, particularly in those already prone to melasma or post-inflammatory hyperpigmentation.
Physical trauma to the skin — Picking at breakouts, aggressive treatments, or any pressure or injury to the skin can trigger a pigment response.
Overly aggressive skincare treatments — Too much exfoliation or the wrong treatment for your skin type can cause inflammation that leads to more pigmentation, not less.
Internal Triggers
Hormones — Pregnancy, perimenopause, menopause, and hormonal imbalances can all trigger melanin overproduction. Melasma, for example, is often called the "mask of pregnancy," but hormonal shifts at any stage of life can cause it.
Medications — Birth control pills, certain antidepressants, diuretics, and some vitamin deficiencies can contribute to hyperpigmentation.
Genetics — Some people are simply more predisposed to pigmentation disorders. If hyperpigmentation runs in your family, or if you have a deeper skin type in your background, your melanocytes may be more reactive — even if your complexion appears fair.
Inflammation — This is the underlying thread that connects almost every form of hyperpigmentation. Any inflammation in the skin, whether from acne, injury, irritation, or sun damage, can trigger excess melanin production.
The Different Forms of Hyperpigmentation
Not all hyperpigmentation is the same. Understanding which type you have is important, because it shapes both the treatment approach and the products that will be most effective.
Post-Inflammatory Hyperpigmentation (PIH)
PIH develops any time inflammation is present in the skin. It is most commonly associated with acne — those red, purple, or brownish marks that linger long after a breakout has healed. PIH tends to sit more superficially in the skin and often has a red or purple undertone in lighter skin tones. In deeper skin tones, it can appear as dark brown or even ashy spots. Because acne is both a form of inflammation and often leads to picking or touching the skin, it is a particularly common cause of PIH.
Sun Damage / Photoaging
When skin has been exposed to UV rays over time without adequate protection, the melanocytes become damaged and begin to misfire — producing pigment in an uneven, scattered pattern. This shows up as the classic dark spots, age spots, or sun spots most commonly seen on the face, hands, chest, and shoulders. Unlike a temporary tan, this type of pigmentation reflects cumulative, long-term UV damage that has disrupted normal melanocyte function.
Melasma
Melasma is a specific type of hyperpigmentation that tends to appear in a more mask-like pattern — often symmetrically across the cheeks, forehead, upper lip, and chin. It is deeply linked to hormonal influences, which is why it commonly appears during pregnancy, while using hormonal birth control, or during perimenopause and menopause. Melasma can also be triggered by certain medications. It tends to be one of the more stubborn forms of hyperpigmentation because the triggers are often ongoing, and heat and UV exposure can cause rapid re-darkening even after improvement.
The Important Truth About Melanocyte Damage
Here is something I want every client to understand: when a melanocyte is damaged, it will always carry that damage. You can manage, reduce, and prevent hyperpigmentation — and we absolutely can improve it significantly — but the goal of treatment is not to eliminate the melanocyte. It is to interrupt the process that causes it to misfire and overproduce pigment.
This is why consistent, ongoing care matters. It is also why prevention is genuinely easier than correction. The most effective thing you can do for hyperpigmentation — regardless of your skin tone or age — is daily SPF, every single day, rain or shine, year round. And the earlier you start, the better.
In Part Two of this series, I'll go into the treatments, ingredients, and professional services — including tyrosinase inhibitors, chemical peels, and advanced corrective protocols — that can actively address and reduce hyperpigmentation. We'll talk about what to look for in products, what to expect from professional treatments, and how to build a realistic plan for your skin.
Have questions about your skin? I'd love to hear from you. You can book a consultation at here, or reach me at mpskintherapy@gmail.com. I'm located inside Wish Electrolysis & Laser Center in Fitchburg, MA, serving clients throughout Central Massachusetts.