Dark spots on the face are caused by excess melanin, the pigment that gives skin its color. The most common triggers are sun exposure, hormonal changes, inflammation from acne or injury, certain medications, and nutritional deficiencies. Understanding which type you’re dealing with matters because each one behaves differently and responds to different approaches.
How Dark Spots Form
Your skin contains specialized cells called melanocytes, which sit in the deepest layer of your epidermis. Each melanocyte serves about 40 surrounding skin cells, delivering tiny packages of pigment called melanosomes through branch-like extensions. When something triggers a melanocyte to ramp up production, or when pigment gets trapped where it shouldn’t be, you see a dark spot.
The key enzyme in this process converts the amino acid tyrosine into melanin through a chain of chemical reactions. Anything that activates this enzyme, whether it’s UV light, inflammation, or hormonal signals, can push melanin production into overdrive. The depth of the pigment in your skin determines how the spot looks and how long it takes to fade. Pigment sitting in the upper skin layers appears brown or black and is generally easier to treat. Pigment that has dropped into the deeper dermis looks grey-blue and can take years to resolve on its own.
Sun Exposure: The Most Common Cause
Chronic UV exposure is the single biggest driver of dark spots on the face. When UV rays hit your skin, they damage DNA in skin cells, which activates a protective response that ramps up melanin production. Over time, this leads to flat brown patches commonly called sun spots, age spots, or liver spots (the medical term is solar lentigines). Despite the nickname, liver spots have nothing to do with your liver.
These spots typically show up on areas that get the most sun: the forehead, cheeks, nose, and upper lip. They tend to accumulate with age simply because you’ve had more cumulative sun exposure. Unlike freckles, which often fade in winter, solar lentigines are permanent changes in how your skin produces and stores pigment. They don’t resolve on their own once established.
Both UVA and UVB rays contribute, but visible light also plays a role, particularly for darker skin tones. This is why broad-spectrum sunscreen with at least SPF 30 is the baseline recommendation for preventing new spots. Tinted sunscreens containing iron oxide offer an added advantage because they block visible light as well as UV. In one study, tinted sunscreens were more effective than non-tinted versions at preventing pigmentation relapses.
Hormonal Changes and Melasma
Melasma produces larger, symmetrical patches of discoloration, usually across the cheeks, forehead, upper lip, or bridge of the nose. It’s strongly linked to estrogen and progesterone, which is why it’s most common in pregnant women, women taking birth control pills, and women on hormone replacement therapy during menopause. It can also affect men, though this is less common.
The good news is that melasma often fades on its own over several months once the hormonal trigger is removed, whether that means delivering a baby or stopping a hormonal medication. The bad news is that it tends to come back with future pregnancies or if you restart the same medications. Sun exposure makes melasma significantly worse, so consistent sun protection is essential for anyone prone to it.
Post-Inflammatory Hyperpigmentation
If you’ve ever had a pimple, cut, burn, or rash leave behind a dark mark long after the skin has healed, that’s post-inflammatory hyperpigmentation (PIH). Inflammation in the skin triggers a cascade of chemical signals that stimulate melanocytes to produce more pigment and distribute it to surrounding cells. The worse the inflammation and the longer it lasts, the darker and more persistent the mark tends to be.
Acne is one of the most common causes. When a breakout triggers an immune response, the resulting inflammation increases melanocyte size and activity. Inflammatory molecules boost the key enzyme responsible for melanin production, flooding nearby skin cells with excess pigment. If the inflammation is severe enough to damage the bottom layer of the epidermis, pigment can leak into the deeper dermis, where immune cells engulf it and hold onto it for months or even years.
This is why picking at acne or aggressively scrubbing inflamed skin makes dark marks worse. The additional trauma deepens the inflammatory response and pushes more pigment into the dermis. Shallow, epidermal PIH from a mild breakout might fade in a few weeks to months. Deeper, dermal pigmentation from cystic acne or significant skin injury can persist for years without treatment.
Why Darker Skin Tones Are More Affected
People with medium to deep skin tones are significantly more prone to post-inflammatory hyperpigmentation. This comes down to biology: darker skin has melanocytes that are more active at baseline, and the melanosomes they produce are larger and more widely distributed throughout the skin cells. The result is that any inflammatory trigger, whether it’s acne, eczema, or a minor scrape, is more likely to leave a visible dark mark, and that mark tends to be more pronounced and longer-lasting.
Interestingly, while darker skin tones are more susceptible to PIH and melasma, lighter skin tones are more vulnerable to solar lentigines because they have less natural UV protection. Every skin tone can develop dark spots, but the dominant type varies.
Medications That Cause Discoloration
Certain medications can trigger dark patches on the face as a side effect. Antimalarials are among the most frequently implicated, with hyperpigmentation considered one of their most common skin-related side effects. Chemotherapy drugs, some antibiotics (particularly minocycline), heart rhythm medications like amiodarone, and certain antipsychotic drugs can also cause discoloration. Heavy metals including gold, silver, and mercury are well known for causing pigment disturbances as well.
Drug-induced pigmentation often has a distinctive pattern or color depending on the medication involved. If you’ve noticed new dark spots after starting a medication, that connection is worth discussing with whoever prescribed it. The discoloration sometimes reverses after stopping the drug, but not always.
Vitamin B12 Deficiency
A lesser-known cause of facial dark spots is vitamin B12 deficiency, which is especially common in people who follow vegetarian or vegan diets. About 1 in 5 people with B12 deficiency develop hyperpigmentation, and in some cases it’s the only symptom. The darkening tends to appear on the face, hands, feet, palms, and soles.
B12 deficiency causes excess pigment through several pathways. Low B12 reduces levels of an antioxidant that normally keeps the pigment-producing enzyme in check, allowing melanin synthesis to increase. The deficiency also disrupts the normal transfer of pigment between cells, leading to pigment leaking into areas where it doesn’t belong. The encouraging part is that this type of hyperpigmentation is fully reversible. Once B12 levels are restored, the dark spots typically clear within 6 to 12 weeks.
How Doctors Identify the Type
Because treatment depends on the cause, dermatologists use specific tools to figure out what kind of dark spots you have. One of the most useful is a Wood’s lamp, which shines a specific wavelength of ultraviolet light onto your skin in a darkened room. Under this light, pigment sitting in the upper epidermis appears as sharply defined brown or black patches, while pigment trapped deeper in the dermis shows up as unaccentuated grey-blue areas. This distinction matters because epidermal pigment responds much better to topical treatments, while dermal pigment is stubbornly resistant and may require more intensive approaches.
Your dermatologist will also consider the pattern and distribution of the spots. Symmetrical patches across both cheeks point toward melasma. Scattered flat brown spots in sun-exposed areas suggest solar lentigines. Dark marks that map exactly to where you had acne or an injury indicate PIH. The location, shape, and your medical history usually tell the story.
Protecting Against New Spots
Regardless of the underlying cause, UV exposure makes virtually every type of dark spot worse and triggers new ones. Daily broad-spectrum sunscreen with SPF 30 or higher is the single most effective preventive measure. For people with darker skin tones or melasma, tinted sunscreens are worth considering because they contain iron oxide, which blocks visible light that untinted sunscreens miss entirely. Adding antioxidants like vitamins C and E or niacinamide can enhance the protective effect.
Beyond sunscreen, managing the root trigger is essential. That means treating active acne before it has a chance to leave marks, addressing hormonal contributors when possible, checking B12 levels if you’re at risk for deficiency, and reviewing your medication list if new spots have appeared without another explanation. Dark spots are almost always treatable, but preventing them in the first place is far easier than fading them after they’ve formed.