Melasma is the type of hyperpigmentation that makes people feel like they are doing everything right and getting nowhere. The routine is consistent. The sun protection is diligent. The products are evidence-based. And still, the pigment returns. Sometimes in the same place. Sometimes darker than before.
That is not a failure of effort. It is the nature of melasma. It does not follow the same rules as other pigment types. It is not a stain left behind by a single event. It is a chronic signalling pattern in which the melanocytes themselves are in a state of ongoing hyperactivity, driven by triggers that are harder to control and more varied than most people realise.
The reason this distinction matters so urgently is that the standard approach to hyperpigmentation (exfoliate, brighten, accelerate turnover) is built for post-inflammatory marks. Applied to melasma, it frequently makes things worse. Understanding what melasma actually is, how it behaves, and what drives it is the foundation that everything else depends on.
What it looks like
Melasma presents as patches of pigmentation rather than discrete spots. The patches tend to be larger, more diffuse, and less sharply defined than PIH marks or sun spots. The edges blend into surrounding skin rather than cutting off cleanly.
The colour ranges from light brown to dark brown to grey-brown, depending on depth and skin tone. When pigment sits in the epidermis, it appears brown and relatively warm. When it extends into the dermis, the colour shifts toward grey, ashy, or muted. Many melasma patches have both components, producing a layered appearance that changes with lighting conditions.
One of the most distinctive visual features of melasma is its symmetry. The patches tend to appear in matching positions on both sides of the face, which reflects the systemic nature of what is driving it. Hormonal and vascular triggers do not target one cheek. They affect the skin broadly, and the melanocytes in certain facial regions are more responsive to those signals.
Where it appears
Melasma follows recognisable distribution patterns that dermatologists classify by location.
Centrofacial is the most common pattern, accounting for the majority of cases. Pigment appears across the forehead, cheeks, nose, and upper lip. The bridge of the nose and the centre of the forehead are often involved.
Malar involves the cheeks and nose specifically, producing what many people describe as a mask-like appearance across the mid-face.
Mandibular appears along the jawline. This pattern is less common but is seen more frequently in post-menopausal women and can be harder to recognise as melasma because people associate the condition primarily with the cheeks and forehead.
Melasma almost exclusively affects the face. Body involvement is rare and, when it does occur, usually appears on the forearms or neck in the context of significant UV exposure. If pigment matching a melasma-like pattern appears elsewhere on the body, other diagnoses are more likely.
The distribution pattern is a strong identification marker. Symmetrical, patch-like pigment on the central face in someone with a hormonal history (pregnancy, contraceptives, perimenopause) is melasma until proven otherwise.
What triggers it
Melasma is a multi-trigger condition. Rarely is a single factor responsible. More commonly, several triggers operate simultaneously, which is one of the reasons it is so persistent: addressing one while the others continue running is not enough to stop the signalling.
Hormonal shifts are the most established driver. Oestrogen and progesterone directly increase melanocyte sensitivity, lowering the threshold for pigment production. Pregnancy is the most recognised context (melasma is still sometimes called the "mask of pregnancy"), but hormonal contraceptives, hormone replacement therapy, and perimenopause all carry the same risk. The pregnancy and birth control pages in the Hyperpigmentation causes cover these mechanisms in detail.
UV radiation does not cause melasma on its own, but it is the most potent amplifier. Even brief, incidental UV exposure can reactivate a melasma patch that appeared to be fading. UVA penetrates into the dermis and generates the oxidative stress that keeps melanocytes reactive. This is why melasma commonly worsens in summer and improves in winter without fully resolving.
Visible light is the trigger most people miss. Blue and violet wavelengths (400 to 500 nm), including light from screens and indoor sources, activate melanocytes through a separate opsin receptor pathway that has nothing to do with UV. This effect is significantly stronger in melanin-rich skin. Standard sunscreens that block UV but not visible light leave this pathway completely uncovered.
Heat activates melanocyte signalling through vascular and inflammatory mechanisms that are independent of light exposure entirely. Cooking over a stove, hot environments, saunas, heated car interiors, even hot showers directed at the face. Heat is one of the most under-recognised melasma triggers, and it explains many cases where pigment worsens despite seemingly adequate sun protection.
Inflammation and stress act as background amplifiers. Chronic stress elevates cortisol, which sustains the inflammatory signalling that keeps melanocytes reactive. Poor sleep compounds the effect by disrupting the repair cycles the skin depends on. These factors rarely cause melasma on their own, but they lower the threshold at which other triggers produce a visible response.
The layered nature of melasma triggers is what makes it so different from PIH. A post-inflammatory mark has one cause, and removing it stops the process. Melasma has multiple simultaneous inputs, some of which (hormones, ambient light, heat) are difficult or impossible to eliminate completely.
How it behaves over time
Melasma does not follow a linear fading trajectory. It cycles. Patches can lighten with treatment and sun avoidance, darken again with seasonal UV increase or a hormonal shift, partially improve over winter, and reactivate the following summer. The pattern can repeat for years.
This behaviour is one of the most reliable ways to distinguish melasma from other types. PIH moves in one direction: toward resolution. Sun spots are stable. Melasma fluctuates. If your pigment fades in winter and returns in summer, if it darkens during your cycle or after a stressful period, if it responded to treatment and then came back, the cycling pattern itself is diagnostic information.
The reason melasma cycles is that the melanocytes involved are not simply overproducing pigment in response to a one-time event. Research suggests they exist in a state of chronic hyperactivity where the signalling infrastructure (vascular networks, inflammatory mediators, hormonal receptors) remains upregulated even when the visible pigment improves. The pigment fades, but the system that produces it stays primed. When a trigger returns, production restarts from an already-elevated baseline.
This is the single most important thing to understand about melasma. The visible patch is the output. The underlying signalling state is the condition. Treatment that addresses only the output without stabilising the signalling will produce temporary results at best.
The melasma timeline covers realistic expectations for what improvement looks like over months and years.
How deep it typically sits
Melasma is frequently deeper than it appears, and underestimating its depth is one of the most common reasons treatment produces disappointing results.
Epidermal melasma involves pigment in the upper skin layers. It appears brown with relatively clearer edges and tends to respond more readily to topical treatment and sun avoidance. This is the most treatable presentation.
Dermal melasma involves pigment that has reached the deeper dermis. It appears blue-grey or ashy with less defined borders. At this depth, topical ingredients have limited reach, and clearance depends on the much slower macrophage-mediated process. Dermal melasma is the form most likely to persist for years.
Mixed melasma is the most common presentation in clinical practice. Both epidermal and dermal components are present. The epidermal layer may respond to treatment, giving the impression of progress, while the dermal component persists underneath. This is the "plateau" that many people experience: initial improvement followed by a stubborn residual that does not budge.
Traditional assessment uses a Wood's lamp to distinguish epidermal from dermal pigment. Under UV light, epidermal pigment becomes more prominent (enhanced), while dermal pigment shows little change. Mixed melasma shows partial enhancement. This assessment is not always definitive, particularly on darker skin tones where the contrast is less pronounced, but it provides a useful baseline for setting expectations.
The practical implication of depth: if treatment is producing visible lightening at first and then stalling, it does not necessarily mean the approach is wrong. It may mean the accessible pigment has improved and what remains is sitting deeper, requiring a different timeline and possibly a different strategy.
Relapse risk
Melasma has the highest relapse rate of any common hyperpigmentation type. This is the defining feature that separates it from everything else.
The relapse is not a sign that treatment failed. It is a predictable consequence of the underlying biology. The melanocytes involved do not return to a normal baseline after treatment. They remain sensitised, with upregulated receptors and an expanded vascular network that keeps them responsive to triggers. When those triggers return (and with hormones, UV, visible light, and heat, they almost always do), pigment production resumes.
Published relapse rates for melasma vary by study, but the pattern is consistent: the majority of people who achieve significant improvement experience some degree of recurrence within months to a year of stopping active treatment, especially over summer.
This does not mean improvement is pointless. It means the concept of "cured" does not apply to melasma the way it does to PIH or sun spots. Melasma is managed, not cured. The treatment goal shifts from "get rid of it" to "keep it at a level you are comfortable with, sustainably." The people who do best long-term are the ones who build trigger control and maintenance into their routine as an ongoing discipline rather than a phase with an end date.
How it is commonly confused
Melasma vs PIH is the single most consequential misidentification in pigmentation care. Both present as dark patches on the face. But PIH is tied to a specific event, is not symmetrical, and tolerates more aggressive treatment. Melasma is hormonal, symmetrical, and frequently rebounds when treated with the same intensity that PIH handles well. The PIH vs Melasma comparison covers the full distinction.
Melasma vs sun spots causes confusion because both appear on sun-exposed areas. The difference is in the pattern and behaviour: melasma is symmetrical, diffuse-edged, and reactive. Sun spots are discrete, well-defined, and stable. Melasma fluctuates with hormones and seasons. Sun spots do not. The Melasma vs Sun Spots comparison covers this.
Melasma vs heat-triggered pigmentation is a subtler distinction because heat is a known melasma trigger. The question is whether the pigment is part of a broader melasma pattern with hormonal involvement, or whether it is triggered purely by heat without the hormonal component. The overlap is real, and in some cases both are present. The Melasma vs Heat-Triggered comparison helps sort through the distinction.
Melasma vs drug-induced pigmentation can occasionally overlap, particularly with oral contraceptives, which can trigger genuine melasma. Other medications (antimalarials, certain psychiatric drugs) produce pigment changes with different distribution patterns, often blue-grey and in locations that do not match typical melasma distribution. The medication-related pigmentation article covers the medications most commonly involved.
When to see a dermatologist
Melasma benefits from professional evaluation more than most other types, because its chronic nature, depth ambiguity, and relapse risk make self-directed management harder to sustain without a baseline assessment.
At the point of identification. If you suspect melasma but are not certain, a dermatologist can confirm the diagnosis, assess depth with a Wood's lamp, and rule out other conditions. Starting with the right identification prevents months of misdirected effort.
If pigment is worsening despite careful trigger management. When sun protection, heat avoidance, and topical treatment are all in place and the pigment is still progressing, there may be a hormonal or internal factor that needs evaluation. This is especially relevant for women who have recently changed contraception, entered perimenopause, or have thyroid concerns.
Before any clinical procedure. Lasers, deep peels, and aggressive treatments on melasma carry a higher risk of rebound than on other types. A dermatologist experienced with melasma can assess whether a procedure is appropriate for your specific presentation, skin tone, and depth profile.
If melasma appeared suddenly and you are not pregnant or on hormonal medication. Sudden onset without an obvious hormonal trigger is worth investigating, as it can occasionally point to a thyroid issue or other hormonal imbalance.
Melasma is not a stain waiting to be removed. It is a signalling pattern that can be quieted, managed, and significantly improved, but rarely switched off entirely. The people who do best with it are the ones who understand what they are working with.
