Three Different Things Get Called "Dark Spots"
Before treating hyperpigmentation, it helps to know which kind you actually have. The cause changes what's worth trying first.
Post-Inflammatory Hyperpigmentation (PIH) From Acne Marks
PIH is the flat, brownish or reddish-brown mark left behind after a pimple, insect bite, cut, or aggressive extraction heals. It isn't scarring in the textural sense — the skin surface is usually smooth. It's a pigment response to the inflammation that happened underneath. PIH is common across all skin tones. It tends to be more pronounced and longer-lasting in medium-to-deep skin tones, where melanocytes are more reactive to inflammatory triggers.
Sun-Induced Spots (Solar Lentigines aka Sunspots)
Often called sunspots, age spots, or liver spots. That last name is misleading — they have nothing to do with the liver. These are flat brown patches that build up gradually from cumulative UV exposure. They typically show up on the face, hands, chest, and shoulders. Those are the areas that get the most sun over a lifetime. They're most common in fair-to-medium skin tones and tend to appear from a person's 30s onward. Early sun damage from childhood and adolescence plays a large role in when they show up. Broad-spectrum sunscreens like EltaMD's UV Clear are the single best defense against new sun spots forming in the first place.
Melasma
Melasma looks different from the other two. It's a larger, patchy discoloration. It's often symmetrical, usually across the cheeks, forehead, upper lip, or nose bridge. It's driven primarily by hormonal changes — pregnancy, birth control, hormone therapy. UV and even visible light exposure make it worse. That's why melasma is notoriously more resistant to standard brightening ingredients and more prone to relapse.
What Triggers Melanocytes: UV Exposure, Inflammation & Hormonal Changes
All three forms trace back to melanocytes. These specialized cells manufacture melanin, the pigment that gives skin its color. Melanocytes are reactive. Expose them to UV exposure, inflammation, or certain hormonal changes, and they ramp up production. A breakout, a sunburn, or a hormonal shift can all set this process in motion.
What's Happening Underneath the Skin: Melanocytes, Tyrosinase, Melanin & Keratinocytes
Melanocytes ramp up an enzyme called tyrosinase. That's the first step in converting an amino acid (tyrosine) into melanin. That melanin then gets packaged and transferred into surrounding skin cells, called keratinocytes. This is what makes the pigment visible as a spot or patch, once the original trigger has resolved.
Why Some Skin Tones Show It More Visibly and For Longer
Melanocyte activity varies by skin tone. The number of melanocytes in skin is actually similar across ethnicities. What differs is how reactive they are, and how much melanin they produce per trigger. Medium and deep skin tones tend to have more melanocyte reactivity. The same pimple or sunburn can leave a more pronounced, longer-lasting mark than it would on fair skin. This is part of why post-inflammatory hyperpigmentation is such a common, frustrating concern for people with more melanin-rich skin. That holds even when the original acne or irritation was mild. Brightening picks like The Ordinary's alpha arbutin serum won't change how reactive melanocytes are — they just interrupt the pigment those cells produce.
Why Dark Spots Don't Disappear Overnight
Once melanin has been deposited into skin cells, clearing it isn't instant. There's no way to erase pigment that's already there — skin has to gradually cycle it out. That happens through two overlapping processes. First, the skin's natural turnover: pigmented cells at the surface are shed and replaced over several weeks. Second, ideally, a slowdown in new melanin production, so the spot isn't being replenished as fast as it's fading. This is why brightening ingredients are used consistently over months rather than as a one-time treatment. Unprotected sun exposure during that process can effectively cancel out the progress being made.
When a Spot Needs More Than a Skincare Routine: See a Dermatologist
Not every mark that looks like a dark spot is hyperpigmentation from acne, sun, or hormones. Some spots need a closer look. Watch for a spot that's changing in size, shape, color, or border, or that's raised, bleeding, or itching. The same goes for anything that simply doesn't fit the pattern of a fading post-breakout or sun mark. Get it checked by a dermatologist rather than treating it as a cosmetic concern.
