Melasma — the symmetric brown or gray patches typically on the forehead, cheekbones, upper lip, and jawline — is one of the most stubborn pigmentary conditions to treat. Its cause is well-characterized but the triggers are hard to fully avoid.
The three primary drivers:
- Hormones. Estrogen and progesterone activate melanocytes and increase melanin synthesis. Melasma commonly appears during pregnancy (chloasma / "mask of pregnancy") or on hormonal contraception. Also worsens through perimenopause for some women. Any hormonal shift can trigger or worsen it (Passeron, 2013).
- UV exposure. UV is the most reliable and rapid trigger. A single day of sun exposure can undo weeks of treatment. Sunscreen is the foundation of every treatment plan.
- Heat and visible light. Melasma responds to visible light and infrared radiation as well as UV. Iron oxide-containing tinted sunscreens are particularly protective because they block visible light too.
Genetics and skin phototype: Melasma is much more common in women with Fitzpatrick III-V skin (medium to darker tones), and there's a clear familial pattern.
Treatment. Long-term. Foundational sunscreen (including visible light protection). Prescription options include hydroquinone, triple combination cream (hydroquinone + retinoid + steroid), tranexamic acid (oral or topical), and azelaic acid. Laser treatments require expertise; the wrong laser can worsen melasma dramatically.
Blood work relevant to management: estradiol, hs-CRP.