Melasma refers to a change in skin pigmentation, specifically an overproduction of melanin that creates darker patches on the skin. These patches are typically brown to grayish-brown, appear symmetrically on the face, and develop gradually rather than overnight. The condition affects between 1.5% and 33% of the population depending on the group studied, with women affected nine times more often than men.
How Skin Color Changes in Melasma
Your skin gets its color from a pigment called melanin, produced by specialized cells in the outer layer of skin. These cells manufacture melanin and package it into tiny compartments, then transfer those pigment packages to the surrounding skin cells. This process is what gives skin its normal tone.
In melasma, this pigment-production system goes into overdrive. The pigment-producing cells in affected areas are physically larger than normal and contain more pigment packages than cells in unaffected skin. The result is patches of skin that are noticeably darker than your natural complexion, most commonly appearing on the cheeks, forehead, bridge of the nose, upper lip, and chin.
The depth of the color change matters. Melasma pigment can sit in the outer skin layer (epidermal), deeper in the skin (dermal), or both (mixed). Epidermal melasma tends to look brown and responds better to treatment. Dermal melasma appears more bluish-gray and is harder to treat because the excess pigment is trapped deeper. Dermatologists can distinguish between these types using a special ultraviolet lamp: epidermal pigment becomes more visible under the light, while dermal pigment does not.
Why Pigment Production Increases
Melasma doesn’t have a single cause. Instead, several forces converge to push pigment-producing cells into overactivity.
Hormones: Estrogen and progesterone are powerful drivers. Pigment-producing cells in melasma patches have more hormone receptors than normal skin and are hypersensitive to hormonal stimulation. When estrogen binds to these receptors, it ramps up the activity of the key enzyme responsible for melanin production in a dose-dependent way, meaning more hormone equals more pigment. Progesterone works through a separate signaling pathway but produces the same end result: increased melanin output. This hormonal connection explains why melasma appears in 15% to 50% of pregnant women and why oral contraceptives can trigger or worsen it.
Sunlight: Chronic sun exposure plays a critical role, and not just from UV rays. High-energy visible light (the blue-violet portion of the spectrum) and long-wave UVA are particularly problematic. Blue light activates a light-sensing receptor on pigment cells that directly stimulates melanin production. It also generates oxidative stress in the skin, which further drives pigmentation. This is why melasma tends to flare in summer and improve in winter, and why sun protection is non-negotiable for anyone managing the condition.
Genetics: Family history is a meaningful risk factor. Research analyzing melasma skin samples has found 279 genes with increased activity and 152 with decreased activity compared to normal skin. Many of these are directly involved in melanin production, but others affect inflammation, blood vessel growth, and cell signaling pathways. One gene in particular, called H19, is less active in melasma patches. When this gene is suppressed, pigment production increases and more melanin gets transferred to surrounding skin cells.
Who Is Most Affected
Melasma is more common in people with medium to darker skin tones and is particularly prevalent in those with light brown complexions. People of any race can develop it, but those with more active pigment-producing cells are at higher risk. The strong hormonal connection means women bear the overwhelming majority of cases, though men do develop melasma as well.
Managing the Pigment Change
Treatment targets the excess melanin at various points in its production cycle. The gold standard topical approach combines three active ingredients: one that blocks the key pigment-producing enzyme, a retinoid that helps the first ingredient penetrate deeper into the skin, and a mild anti-inflammatory that reduces irritation from the other two. This combination addresses pigment production, speeds skin cell turnover, and calms inflammation simultaneously.
For cases that don’t respond well to topical treatment alone, an oral medication originally developed to control bleeding has shown effectiveness. It works by disrupting the communication between skin cells and pigment-producing cells, reducing mast cell activity and blocking growth signals that stimulate melanin production. Laser treatments using low-energy pulses can also help by shrinking the extensions of pigment cells and breaking down pigment packages without damaging surrounding tissue.
The challenge with melasma is that it tends to come back. Recurrence rates in studies range from 0% to 50% depending on the follow-up period, and dermatologists warn patients that melasma can persist for 10 to 20 years. The pigment-producing cells remain primed for overactivity even after successful treatment, so any trigger (sun exposure, hormonal shifts, heat) can restart the cycle.
Why Sunscreen Choice Matters
Standard sunscreens that block only UV rays leave a significant gap in protection for melasma. Visible light, particularly the blue-light wavelengths emitted by the sun and electronic screens, can trigger pigmentation on its own and works synergistically with UVA to worsen it in medium to darker skin tones.
Tinted sunscreens containing iron oxides fill this gap. Red, yellow, and black iron oxides each block different portions of the visible light spectrum, and when combined with zinc oxide, they provide broad coverage against both UV and high-energy visible light. In a controlled trial comparing tinted and non-tinted sunscreens with identical UV filters, patients using the tinted version had significantly fewer melasma relapses over six months. Notably, patients in the non-tinted group who wore makeup did not see the same benefit, highlighting that the specific protection from iron oxides matters more than simply having a pigmented layer on the skin.