TL;DR
PIH is a dark spot left by a specific injury (acne, bite); melasma is symmetrical brown patches driven by hormones and sun that appear on both cheeks, forehead, or upper lip.
- PIH shape
- Irregular, follows the old injury
- Melasma shape
- Symmetrical patches, both sides of face
- Main driver
- PIH: injury · Melasma: hormones + UV
- Common in
- Melasma peaks in women 20–40 in MY & ID
The direct answer
Post-inflammatory hyperpigmentation (PIH) traces the exact spot of past inflammation — a healed pimple leaves one dark dot.
Melasma appears as bilateral, blotchy brown patches, usually across the cheeks, upper lip, and forehead, and is triggered by oestrogen, pregnancy, birth control, and sun.
How to tell them apart
- PIH = one mark where something happened (acne, burn, bite).
- Melasma = matching patches on both sides, often worsens in pregnancy or with heat.
- Melasma sits deeper (dermis) and is far more stubborn than surface PIH.
Why the distinction matters for treatment
Both need strict sun protection, but melasma responds better to tranexamic acid and avoids irritation that can flare it; harsh scrubs that help acne can worsen melasma.
FAQ
Can melasma be cured?
It cannot be permanently "cured", but it can be controlled. Strict daily sunscreen plus tranexamic acid keeps patches faint; relapse is common with UV or hormone changes.
Does pregnancy melasma go away?
Often it lightens after delivery when hormone levels fall, but sun exposure during pregnancy can lock in the pigment. Sunscreen from the first trimester helps.
Can I treat both PIH and melasma together?
Yes. A gentle routine with niacinamide, tranexamic acid, and SPF 50+ targets both without the irritation that aggravates melasma.