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A complete guide to melasma — the UV-hormone-inflammation triad pathogenesis, evidence for topical treatments (hydroquinone, azelaic acid, tranexamic acid), professional treatments (peels, lasers, microneedling), and why recurrence is the central challenge.
· By MedSpot Editorial · 6 min read
Melasma is one of the most frustrating conditions in dermatology — not because it can't be treated, but because it almost always returns. Understanding why melasma recurs is as important as understanding what treats it. Here's the complete picture.
Melasma is acquired hyperpigmentation of sun-exposed skin — brown to gray-brown patches appearing predominantly on the cheeks, upper lip, forehead, chin, and bridge of the nose. It is not a skin cancer and causes no health risk; it is a cosmetic condition with significant psychological impact.
Epidemiology: Disproportionately affects women (90% of cases), people with Fitzpatrick III–VI skin tones, and those with high UV exposure. Prevalence in some South Asian and Latin American populations reaches 30–40%.
Melasma requires the intersection of three factors — addressing all three is what separates successful treatment from temporary improvement:
UV activates keratinocytes → release of prostaglandins, nitric oxide, and stem cell factor → melanocyte stimulation → increased melanin production. UVA in particular (which penetrates glass and is not blocked by most daily activities) is a continuous stimulus.
Critical implication: Any treatment for melasma that does not include rigorous daily UV protection is doomed to fail. UV is a continuous, daily melanocyte activator.
Estrogen and progesterone stimulate melanocyte activity — explaining why melasma is triggered or worsened by:
The hormonal mechanism explains why melasma is so much more prevalent in women, why it often appears or worsens during pregnancy, and why switching to progesterone-only contraceptives or discontinuing OCP sometimes helps.
Melasma-affected skin shows increased vascularity vs. surrounding skin — vascular endothelial growth factor (VEGF) is elevated, and the blood vessels in melasma lesions are more numerous and dilated. This vascular component contributes to the inflammatory stimulus that keeps melanocytes activated.
Implication: Treatments targeting vascularity (tranexamic acid, certain laser wavelengths targeting oxyhemoglobin) address a component that purely tyrosinase-targeted treatments miss.
Even after successful treatment, melasma-affected skin has permanently sensitized melanocytes — they respond to UV more vigorously than surrounding skin. This is why the moment UV protection lapses, melasma recurs. There is no known treatment that normalizes melanocyte sensitivity; management is maintenance, not cure.
| Type | Melanin location | Wood's lamp | Prognosis |
|---|---|---|---|
| Epidermal | Basal + suprabasal epidermis | Enhanced (bright) | Good response to topicals |
| Dermal | Upper dermis (melanophages) | Not enhanced | Poorer response; needs lasers |
| Mixed | Both | Partially enhanced | Variable |
| Indeterminate | Difficult to classify | — | Variable |
Most melasma is mixed. Pure dermal melasma is the most treatment-resistant form.
Hydroquinone (HQ) inhibits tyrosinase and has additional cytotoxic effects on melanocytes at higher concentrations. It remains the most studied and most effective topical brightening agent.
Kligman-Willis formula (Tri-Luma): FDA-approved combination of hydroquinone 4% + tretinoin 0.05% + fluocinolone 0.01% (low-potency steroid). Multiple RCTs demonstrate superiority over HQ alone; triple combination addresses pigment, cell turnover, and inflammation simultaneously.
Limitations:
FDA-approved for rosacea; excellent evidence for melasma. Selectively inhibits hyperactive tyrosinase in abnormal melanocytes — less risk of affecting normally-pigmented skin. Safe in pregnancy (Category B). Baliña & Graupe 1991 trial: comparable to 2% HQ for melasma.
Inhibits plasmin-driven UV signaling to melanocytes — the upstream step. Ebrahimi 2014: 3% TXA topical comparable to 3% HQ at 12 weeks. Oral TXA has stronger evidence for diffuse melasma. Excellent safety profile.
For patients unable to use hydroquinone:
Glycolic acid peels (20–70%): Accelerate pigmented cell turnover; improve penetration of topicals; modest direct brightening. Risk of PIH in darker skin types — use conservative concentrations.
Jessner's peel: Combination of lactic acid, salicylic acid, and resorcinol; well-established for melasma in darker skin.
TCA (10–15%): More potent; higher PIH risk in Fitzpatrick IV–VI; generally reserved for lighter skin types for melasma.
Optimal approach: Series of 4–6 monthly peels combined with maintenance topical regimen. Peels alone without topical maintenance almost universally results in recurrence.
IPL (Intense Pulsed Light): Targets melanin and oxyhemoglobin; can improve melasma but carries significant PIH risk in darker skin. Best for Fitzpatrick I–III.
Q-switched Nd:YAG 1064 nm (low-fluence "toning"): Widely used in Asian dermatology for melasma; multiple sessions at sub-ablative fluences; better safety profile in darker skin than higher-fluence lasers. Evidence is generally positive for improvement, though recurrence remains common.
Picosecond lasers: Faster pulse duration → mechanical (photomechanical) disruption rather than thermal → potentially less PIH risk than nanosecond QS lasers. Growing evidence base; increasingly preferred over Q-switched in darker skin.
Fractionated CO2/erbium: Generally avoid for melasma — heat-induced PIH risk is high; melasma frequently worsens post-ablative laser.
Key rule: Any laser treatment for melasma in Fitzpatrick IV–VI skin must be done by a provider experienced in treating skin of color. PIH from laser in darker skin tones can be severe and difficult to treat.
Microneedling creates microchannels for topical delivery of tranexamic acid directly into the dermis — particularly relevant for dermal melasma that topical-only approaches miss. Multiple small studies show benefit; growing adoption in practice.
Every melasma treatment protocol must include:
Recurrence timeline without sun protection: Most treated melasma returns within weeks to months of UV re-exposure. Some patients require year-round maintenance therapy as a permanent management strategy.
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