The color of your skin, hair, and eyes is determined primarily by a natural pigment called melanin. Melanin is produced by specialized cells in the skin known as melanocytes, which live in the bottom layer of your outer skin. Here's something interesting: every person, regardless of race or ethnicity, has roughly the same number of melanocytes in their skin. The differences in skin tone come from how much melanin those cells produce and the type of melanin produced, which are largely controlled by genetics.

There are two main forms of melanin: eumelanin (brown or black pigment that gives rise to tan, brown, or black hair and darker skin tones) and pheomelanin (red or yellowish pigment present in those with red hair and very fair, freckled skin). Each person has a unique combination of these melanin types. Melanin's main job, aside from giving us our unique coloring, is to protect our skin from ultraviolet radiation. When UV light hits the skin, melanocytes produce more melanin to guard the deeper layers. This protective response is what causes tanning.

Under normal conditions, melanin production throughout your skin is relatively even, giving you a consistent tone. Uneven skin tone arises when certain spots or areas produce more or less melanin than the surrounding skin. If excess melanin is deposited in the upper layer of skin, the dark spot will typically look brown and may fade more easily. If the pigment drops deeper into the lower layer, the discoloration may appear blue-gray and tends to be more stubborn or long-lasting.

Uneven skin tone doesn't look the same for everyone. It manifests differently depending on a person's natural skin color and ethnic background.

Fair Skin

People with very light skin often show uneven tone as reddish or light brown spots. Common examples are freckles (small tan to light-brown spots that become more pronounced with sun exposure) or pink/red marks left after acne lesions. Fair skin may also show obvious redness or rosiness in areas of irritation or sunburn. While freckles tend to fade when not in the sun, decades of sun exposure can lead to larger persistent spots known as sun spots or age spots, which are usually light to medium brown patches that don't fade seasonally.

Medium Skin

People with beige, olive, or light brown skin tones often develop hyperpigmented areas that appear medium to dark brown. Melasma (often affecting women) shows up as blotchy tan-brown patches on the cheeks, forehead, or upper lip. Post-inflammatory marks after pimples or injuries are usually brown in these skin tones. Uneven skin tone in medium complexions often involves a mix of brown patches and an overall dull or ashy tone if the skin has sun damage.

Darker Skin

Individuals with brown to deep ebony skin have high melanin levels naturally, which offers some protection from UV rays but also means their skin reacts vigorously with pigment to any injury or inflammation. In dark skin, uneven tone often presents as very dark brown to blue-black areas of hyperpigmentation. A simple scratch or acne bump can heal with a noticeably darker spot. This is why post-inflammatory hyperpigmentation is more common and severe in deeper skin tones. These spots may look black or dark gray against the surrounding brown skin. Hypopigmentation (areas of lighter skin) in darker individuals stands out dramatically as pale or white against a dark background.

Uneven skin tone can stem from a variety of internal and external causes. Essentially, anything that affects melanin production or distribution in the skin can create dark or light patches.

• Sun exposure is the number one culprit behind most cases of uneven skin tone. UV rays from the sun stimulate melanocytes to produce more melanin as a defense mechanism. Over time, repeated unprotected sun exposure causes certain areas to accumulate excess pigment or develop localized sun spots. Solar lentigines (often called age spots) are flat brown to black spots that appear on sun-exposed areas like the face, hands, and shoulders, typically in people over 40. Even people with deeper skin tones can get uneven darker patches from cumulative sun exposure. UV exposure not only creates new hyperpigmented spots, it can worsen existing discoloration.
• Post-inflammatory hyperpigmentation is the technical term for dark spots or patches that remain after a skin injury or inflammation has healed. It's extremely common, especially in medium to dark skin tones. Any kind of trauma or irritation can trigger melanocytes to go into overdrive. Acne is a prime example: after a pimple resolves, it often leaves behind a brown or dark purple spot, particularly if you have a darker complexion or if the acne was picked at. Other causes include eczema, psoriasis, bug bites, scratches, burns, cuts, or any skin infection. This happens because inflammatory substances released in the skin can stimulate nearby melanocytes to produce extra melanin. Skin tone plays a big role: post-inflammatory hyperpigmentation is more prevalent and long-lasting in individuals with naturally darker skin.
• Hormonal changes can have a significant impact on melanin production. The most well-known hormonally driven pigmentation issue is melasma, sometimes called the "mask of pregnancy." Melasma causes irregular brown or gray-brown patches typically on the face. It predominantly affects women, especially in their 20s to 40s, and is often triggered by hormonal shifts during pregnancy or from birth control pills. Thyroid disorders and other hormonal imbalances have also been linked to melasma or general hyperpigmentation. Interestingly, stress might play a role too, as emerging research suggests that stress hormones can worsen melasma.
• Acne and breakouts are a double hit: first the blemish, then the mark. People with medium to dark skin frequently observe that every pimple heals with a brown or black spot. Even in lighter skin, a deep acne cyst can leave a reddish-brown mark that takes months to fade. The habit of picking or squeezing pimples greatly increases the likelihood of discoloration by creating more inflammation. Beyond acne, other skin conditions that cause frequent inflammation like eczema or psoriasis can similarly lead to patches of hyperpigmentation where the rash was.
• Aging and cumulative damage lead to a more uneven skin tone. This is partly because of external damage accumulated over time (mostly from sun exposure) and partly due to intrinsic aging changes. Many people notice that in their 40s, 50s, and beyond, freckles or slight discolorations become more pronounced or new spots appear. Age spots usually begin to crop up after age 50 (earlier for sun-loving individuals) and are directly tied to long-term UV exposure. Additionally, the skin's natural cell turnover slows down with age. Dead cells hang on longer and pigment deposited in the skin remains around longer as well, contributing to a duller, uneven complexion in older adults.
• Pollution and environmental stressors also contribute. Airborne particulate matter and pollutants can penetrate the skin and generate damaging free radicals. These can trigger pathways in the skin that lead to inflammation and increased melanin production. Some evidence indicates that pollution can activate the same pigment-producing cells and enzymes that UV light does. The result is often a vague darkening or discoloration, especially on the face.

Some discoloration is temporary while other types are quite persistent. Understanding the difference can manage expectations and guide how you care for your skin.

Temporary uneven skin tone refers to pigmentation that will gradually fade or disappear once the triggering factor is removed and the skin has time to regenerate. A suntan will usually fade in a few weeks once you stop getting sun and practice sun protection. Post-inflammatory hyperpigmentation often fades over time. Superficial marks might fade over 3 to 6 months, whereas deeper marks can take months to years to significantly lighten. Melasma triggered by pregnancy or medications can sometimes resolve on its own. Pregnancy melasma often improves within a year after delivery when hormones normalize. Freckles are another type of "transient" pigmentation: they darken with UV exposure and then fade significantly when sun is avoided.

Persistent uneven skin tone is the kind that tends to stick around long term. Sun spots or age spots are considered permanent in the sense that they do not fade on their own when you leave the sun. A sun spot is an accumulation of sun damage where the DNA in that patch of skin has essentially been altered to produce more melanin. Without treatment or removal, those spots usually remain and can even darken further with more sun. Melasma often becomes a long-term condition. Many people have melasma patches that fluctuate but never fully go away on their own. Deep post-inflammatory hyperpigmentation, where pigment sinks into the lower layer of skin, can be very long-lasting. The body has more difficulty clearing pigment that's been dropped into deep skin layers.

It's also helpful to consider that persistent versus temporary can depend on your behavior. If you continue to get sun exposure, a "temporary" post-acne spot might become persistent because you keep refreshing the stimulus. If you break the cycle by avoiding sun and preventing new inflammation, it might have faded. Sometimes whether a discoloration becomes long-lasting is in part due to whether it's repeatedly exacerbated.

Anyone can develop uneven skin tone, but certain factors make it more likely. Your genetic background influences how your skin reacts to various triggers. Some people are simply predisposed to pigmentation issues. Family history plays a role: if your parents have a lot of freckles or age spots, you might inherit that tendency. Likewise, family history is a factor in melasma, often with a genetic susceptibility that, when combined with hormone triggers and sun, leads to melasma in multiple female family members.

Skin phototype, which is largely genetic, determines how much you tan or burn, which then influences uneven tone. Darker skin types not only produce more melanin generally, but their melanocytes are often more "reactive," meaning they respond to insults by increasing pigment production readily. This is protective against UV to a degree, but it also means any scratch or pimple can leave a dark mark. Conversely, very light skin might not hyperpigment much after a scratch but can get patchy from sun in terms of freckles and red blotches.

Certain ethnic backgrounds are more prone to specific pigmentary conditions. Asian and Latinx populations have a higher incidence of melasma. African and Hispanic individuals more commonly develop post-inflammatory hyperpigmentation. People of European descent with Celtic backgrounds tend to freckle easily. Women are more susceptible to melasma due to hormonal factors. People who spend lots of time outdoors without protection are at higher risk for sun-induced uneven tone. Those with active acne or inflammatory skin conditions are more likely to develop post-inflammatory marks.

While you can't control everything, there's quite a bit you can do to prevent or minimize uneven skin tone.

• Daily sun protection is the single most important preventive step. Apply broad-spectrum sunscreen with at least SPF 30 to all exposed skin every morning, even when it's cloudy. Reapply if you're spending extended time outdoors. Wear hats, sunglasses, and seek shade during peak sun hours. Avoid tanning beds. By preventing UV damage, you'll slow the formation of new spots and prevent existing spots from darkening.
• Don't pick or squeeze your pimples. This is crucial if you're prone to post-inflammatory marks. Picking causes more inflammation and increases the chance of a dark mark forming. Instead, treat blemishes with appropriate acne medication. Be gentle with your skin when it has any wound or blemish. The less trauma, the better.
• Gentle skin care routine supports your skin's overall health and can improve uneven tone over time. Use a mild cleanser, moisturize regularly, and consider products with beneficial ingredients like vitamin C (helps brighten), niacinamide (reduces the transfer of melanin to skin cells), or gentle chemical exfoliants. These won't instantly fix discoloration, but with consistent use over months, they can gradually improve skin tone.
• Healthy lifestyle choices matter, too. Eat a balanced diet rich in antioxidants, vitamins, and minerals to support skin health. Stay well-hydrated. Get adequate sleep (7 to 9 hours per night) so your body can repair skin tissues. Manage stress through exercise, meditation, or other relaxation techniques, as chronic stress can worsen conditions like melasma. Don't smoke, as smoking accelerates skin aging and can lead to a sallow, uneven tone.