Dark patches on your skin are areas where your body has produced excess melanin, the pigment that gives skin its color. The most common causes are sun damage, hormonal changes, and inflammation from injuries or skin conditions. Figuring out which one is behind your dark patches comes down to where they appear, what they look like, and what’s been happening in your life recently.
How Excess Pigment Forms
Your skin contains specialized cells that produce melanin. Normally, these cells distribute pigment evenly. But certain triggers, including ultraviolet light, hormones, and inflammation, can push these cells into overdrive in specific areas. UV radiation is the most potent external trigger: it increases the number of pigment-producing cells, ramps up the enzymes that create melanin, and signals surrounding skin cells to pull that pigment upward as a shield for their DNA. This is why nearly every type of dark patch gets worse with sun exposure, regardless of the original cause.
Sun Damage and Age Spots
Flat, well-defined brown spots on your face, hands, forearms, or chest are most likely solar lentigines, commonly called sunspots or age spots. They result from years of cumulative UV exposure, which causes the outer layer of skin to thicken slightly and pack extra melanin into those areas. They affect the vast majority of older adults, and lighter-skinned individuals develop them more frequently, though they occur across all skin tones.
These spots are harmless, but they don’t fade on their own because the underlying skin structure has changed. Any flat brown spot that starts to grow unevenly, develop irregular borders, or change color should be evaluated to rule out something more serious.
Melasma: Hormonal Dark Patches
If your dark patches appear as larger, symmetrical areas on both cheeks, the forehead, upper lip, or jawline, melasma is the most likely explanation. It’s driven by an interaction between hormones and sunlight. UV radiation is implicated in up to 50% of cases, but hormonal shifts are what make certain skin cells hypersensitive to that light in the first place.
Estrogen and progesterone are the primary hormonal players. Pigment-producing cells in melasma-affected skin have more hormone receptors than normal skin, making them extra responsive to fluctuations. This is why melasma affects 14.5 to 56% of pregnant women and 11.3 to 46% of oral contraceptive users. It can also appear during menopause or with hormone replacement therapy. About 10% of cases develop after menopause, showing that even declining hormone levels can shift the balance enough to trigger it.
Melasma is notoriously persistent. It often fades after pregnancy or stopping hormonal medication, but UV exposure can bring it right back. Managing it requires consistent sun protection alongside any treatment.
Dark Marks After Skin Injury
Dark spots that show up exactly where you had a pimple, a burn, a rash, or a cut are post-inflammatory hyperpigmentation (PIH). During any inflammatory event in the skin, the healing process releases signaling molecules that stimulate nearby pigment cells. These include prostaglandins, interleukins, and reactive oxygen species, all part of the normal inflammatory cascade that happens to overshoot in the pigment department.
The depth of the pigment deposit determines how long PIH lasts. Surface-level pigmentation looks tan to dark brown and typically fades over months to a couple of years without treatment. Deeper pigment deposits appear blue-gray and can be permanent if untreated. Acne, eczema, psoriasis, and even aggressive skin treatments like waxing or harsh exfoliation can all leave PIH behind. It’s more common and more pronounced in darker skin tones.
Dark, Velvety Patches in Skin Folds
Dark patches that feel thickened and velvety, concentrated in the folds of your neck, armpits, or groin, point to a condition called acanthosis nigricans. Unlike other forms of hyperpigmentation, these patches have a distinct texture: they feel almost soft and raised rather than flat. In children, the back of the neck is the most common spot.
This is often a visible signal of insulin resistance, meaning your body is producing more insulin than normal to manage blood sugar. The excess insulin stimulates skin cells to reproduce faster, which creates the thickened, darkened appearance. It’s strongly associated with type 2 diabetes, prediabetes, and polycystic ovary syndrome. Weight loss and improved blood sugar control can cause these patches to lighten or disappear, since the underlying trigger is metabolic rather than purely cosmetic.
Treatments That Lighten Dark Patches
The right treatment depends on the cause, but a few approaches work across most types of hyperpigmentation.
Topical lightening agents are the first line for melasma and PIH. Hydroquinone, often combined with a retinoid and a mild steroid, has been the standard since the 1970s. This combination works by slowing melanin production, speeding cell turnover, and reducing inflammation simultaneously. Typical treatment courses last 8 to 16 weeks. Hydroquinone should not be used continuously for more than six months, as prolonged use can paradoxically cause a bluish-gray discoloration called ochronosis.
For people who want to avoid hydroquinone, several alternatives have shown results. Cysteamine cream at 5% concentration applied nightly for 16 weeks has demonstrated significant improvement in melasma. Kojic acid at 1 to 2% is another option, sometimes combined with other agents for a stronger effect. Niacinamide (a form of vitamin B3) works differently from most lightening agents: rather than blocking melanin production, it interferes with the transfer of pigment from melanin-producing cells to surrounding skin cells. Tranexamic acid, used topically at around 5%, reduces the hormonal signaling that drives pigment cells to overproduce.
Laser and Light Treatments
For stubborn dark patches that don’t respond to topical products, in-office procedures are an option. Both intense pulsed light (IPL) and specialized lasers can break up pigment deposits. A study comparing the two for hyperpigmentation found no significant difference in effectiveness after three sessions, though IPL was less painful. Side effects from both were mild and temporary.
Skin tone matters significantly when choosing a procedure. Medium and deep chemical peels carry a higher risk of complications in darker skin, including creating new areas of hyperpigmentation or leaving visible lines where treated and untreated skin meet. Deep peels are generally reserved for the lightest skin tones (Fitzpatrick types I and II) to avoid these risks. If you have medium to dark skin, superficial peels and low-energy laser settings are safer options, though they may require more sessions to see results.
Why Sunscreen Is Non-Negotiable
No treatment for dark patches works well without rigorous sun protection, because UV exposure restarts the pigmentation cycle. But standard sunscreen only blocks part of the problem. Visible light, the kind from sunlight and even indoor lighting, can also worsen hyperpigmentation, particularly in darker skin tones. Regular sunscreens, whether mineral or chemical, don’t block visible light.
Tinted sunscreens solve this gap. They contain iron oxides, which filter visible light wavelengths that untinted formulas miss. For anyone prone to melasma or PIH, a tinted broad-spectrum sunscreen with SPF 30 or higher offers more complete protection than a non-tinted version. Reapplying every two hours during sun exposure remains essential regardless of which type you use.