Hyperpigmentation type decoder — PIH, PIE, melasma, or sun spots?

PIH — Post-Inflammatory Hyperpigmentation

The dark spots left behind after acne, injury, or any skin inflammation. Melanocytes (pigment-producing cells) ramp up melanin in response to inflammation; the pigment deposits in the upper layers of skin. PIH is more common and more severe in skin of color (Fitzpatrick III-VI) because of higher baseline melanin activity.

Visual signature: brown, gray-brown, or dark brown marks at exactly the location of past breakouts. Fades very slowly on its own — 6 to 24 months without intervention.

What actually works:

• Vitamin C (10-20%, stable forms) — antioxidant, slows new melanin production
• Niacinamide 5-10% — interrupts melanin transfer to keratinocytes
• Azelaic acid 10-20% — tyrosinase inhibitor + anti-inflammatory; particularly effective in skin of color
• Tranexamic acid — newer topical agent with growing evidence
• Retinoids — accelerate skin turnover, push pigmented cells up and out
• Hydroquinone 2-4% (prescription strength higher) — gold standard but with risks; use under dermatologist supervision
• Daily mineral SPF — non-negotiable; UV reactivates melanocytes and undoes treatment

Realistic timeline: 12-16 weeks for visible fading; 6+ months for full resolution. Faster with prescription tretinoin + hydroquinone combination.

PIE — Post-Inflammatory Erythema

The pink, red, or purple marks left after acne or injury — NOT brown. The mark is actually dilated tiny blood vessels (capillaries) in the dermis, not melanin. PIE is more common in lighter skin tones (Fitzpatrick I-III). The two get confused constantly because both appear at the site of healed acne.

Visual signature: pink to red to purple flat marks at the location of past acne. The mark blanches (turns white) when you press a finger on it and immediately refills. This blanching test is the easiest way to distinguish PIE from PIH.

What actually works for PIE:

• Time — most fade in 3-12 months without specific treatment
• Daily mineral SPF — prevents further inflammation and slow recovery
• Niacinamide — modest benefit through anti-inflammatory action
• Azelaic acid 15% — reduces inflammation, modest vascular benefit
• Vascular laser (V-Beam, KTP, IPL) — the only highly-effective treatment; clears most PIE in 1-3 sessions
• Topical brimonidine — temporary cosmetic redness reduction (a few hours), doesn't treat the underlying vessel

What doesn't work: vitamin C, hydroquinone, kojic acid, arbutin — these target melanin, which isn't the issue in PIE. Spending six months on a "brightening serum" for PIE is a common waste.

Melasma — hormonally-driven symmetrical patches

Brown to grayish-brown patches, usually symmetrical, on cheeks, forehead, upper lip, and jaw. Strongly hormonally driven — pregnancy ("mask of pregnancy"), birth control pills, and hormone therapy are major triggers. Sun exposure significantly worsens it.

Visual signature: symmetrical patches (cheeks especially), brownish or grayish-brown, often well-demarcated, present even when no acne or injury has occurred in the area. Most common in women 20-50, more common in Fitzpatrick III-V skin.

What actually works for melasma:

• Aggressive daily mineral SPF — broad-spectrum, SPF 50+, reapplied every 2-3 hours. Iron-oxide-tinted mineral SPF additionally blocks visible light, which triggers melasma
• Tranexamic acid — oral (prescription) or topical; one of the most-evidence-based melasma treatments
• Hydroquinone 4% — prescription, often in triple combination cream with tretinoin and corticosteroid (Tri-Luma)
• Azelaic acid 20% — pregnancy-safe option
• Cysteamine cream — newer topical with strong evidence; expensive
• Identify hormonal trigger — birth control review with doctor, evaluate other hormone sources
• Avoid heat exposure — saunas, hot yoga, hot showers on the face trigger flares

Melasma is the hardest pigmentation to treat fully — it tends to recur with sun exposure or hormonal changes. Long-term management, not "cure."

Sun spots / lentigines

Discrete light-brown to dark-brown spots caused by chronic UV exposure. More common after age 40 but can appear earlier with significant cumulative sun exposure. Distinct from melasma — sun spots are discrete (separate from each other), often round or oval, with well-defined edges.

Visual signature: separate round/oval brown spots on sun-exposed areas (face, hands, chest, shoulders). Edges are sharply defined. Color uniform within each spot.

What actually works for sun spots:

• Cryotherapy (liquid nitrogen) — in-office; clears individual spots in one treatment
• Q-switched laser — clears multiple spots, 1-3 sessions
• IPL — good for many spots at once
• Prescription tretinoin — slow but works over 6-12 months
• Hydroquinone — over 8-16 weeks
• Mineral SPF daily — non-negotiable to prevent new ones

How to actually tell them apart

The diagnostic triage:

1. Press a finger firmly on the mark for 5 seconds, release. If it briefly blanches white before returning to color, it's vascular (PIE). If color stays the same, it's pigmented (PIH, melasma, or sun spots).
2. Look at the location pattern. Random scattered marks at past acne sites = PIH. Symmetrical patches on cheeks/upper lip/forehead = melasma. Discrete spots on chronically sun-exposed areas = sun spots.
3. Consider your hormonal context. Pregnancy, oral contraceptives, or HRT + new symmetrical patches = melasma until proven otherwise.
4. Note the color tone. Pink-red-purple = PIE (vascular). Brown-gray-brown = PIH or melasma. Light brown to dark brown discrete spots = sun spots.

The single most important rule for all four types

Daily broad-spectrum SPF. Without it, every treatment fails — UV reactivates pigment formation, dilates vessels, and reverses progress. Mineral sunscreens (zinc oxide, titanium dioxide) work better than chemical for pigmentation because they also block visible light. Tinted formulations with iron oxide add an extra layer of visible-light protection important for melasma and PIH in darker skin tones.