TL;DR
Melasma is symmetric, hormonal pigmentation that responds to UV protection, tranexamic acid, and patient pigment-modulating actives. PIH is patchy, reactive pigmentation that follows inflammation and clears with consistent retinoid plus azelaic acid. Mistaking one for the other wastes months. Both deepen in darker skin tones and need the right protocol matched to phototype.
The single most common pigment question I get sounds simple. Why isn’t my hyperpigmentation fading? The answer almost always starts with the same follow-up: are you sure it’s the kind you think it is? Melasma and post-inflammatory hyperpigmentation look similar on a phone screen and behave completely differently. Eight months of vitamin C does little for melasma; it can do plenty for PIH, given enough time.
How to recognize melasma
Melasma has a fingerprint. The pigment is symmetric, usually appearing across both cheeks, the forehead, the upper lip, and sometimes the chin. The borders are irregular but the overall pattern matches side to side. The color is often a mix of brown, gray-brown, or slate, depending on whether the pigment sits in the epidermis, dermis, or both.
It surges with sun exposure and with hormonal changes: pregnancy (often called melasma of pregnancy or chloasma), oral contraceptives, hormonal IUDs, and perimenopause. It fades modestly in winter and through periods of low UV exposure, then comes back when summer returns.
Texture is unchanged. Melasma skin is smooth. No bumps, no scaling, no roughness. The pigment is the only signal, which is part of why it’s so persistent. There’s nothing visibly inflamed for products to target.
How to recognize PIH
Post-inflammatory hyperpigmentation follows a previous inflammatory event. A pimple, an ingrown hair, a chemical burn from over-exfoliation, a bug bite, a small cut. The pigmentation appears in roughly the same shape as the original lesion. It’s patchy, asymmetric, and confined to specific spots rather than spread across an anatomical region.
The color tends toward brown, sometimes dark brown or near-black in deeper skin tones. There’s no gray-blue component the way melasma can have. Each mark has a clear margin where it transitions to normal skin.
PIH fades on its own, but slowly. Three to 18 months without intervention, longer in deeper phototypes. A specific 2019 study in the Journal of Clinical and Aesthetic Dermatology reported that 67.8 percent of acne-related PIH lesions in Fitzpatrick types IV-VI lasted longer than six months, compared with 22 percent in types I-III. Phototype matters enormously.
Why the treatments differ
Melasma is driven by hormonally responsive melanocytes that are also UV-sensitive. The treatment focuses on UV protection (mineral SPF, hat, sun avoidance), tranexamic acid (oral and topical), low-dose hydroquinone in carefully managed courses, and patient use of tyrosinase inhibitors like kojic acid, arbutin, and azelaic acid. Aggressive treatment can rebound.
PIH is driven by melanocytes responding to inflammation. The treatment is to prevent new inflammation (treating the underlying acne, avoiding picking, gentle exfoliation), accelerate turnover with retinoid, and use anti-pigment actives like azelaic acid, tranexamic acid, and vitamin C. Aggressive treatment is better tolerated than in melasma.
Hydroquinone is more useful for PIH than for melasma in the long term. Melasma rebound after hydroquinone discontinuation is well-documented; PIH responds and stays cleared more reliably.
Lasers cut both ways. Q-switched and pico lasers can help PIH but often worsen melasma by adding heat that triggers more pigment. Picosecond fractional with careful settings shows the best evidence for melasma; even then, recurrence rates approach 50 percent at one year.
What actually helps
For both, daily mineral SPF 30 or 50, reapplied every two hours of sun exposure, hat outdoors, iron oxide-tinted sunscreens for visible light protection (which matters more than UV for melasma in some studies). This is the foundation. Skipping it makes everything else half-effective.
For melasma: oral tranexamic acid 250 to 500 mg twice daily under derm supervision, topical tranexamic acid 3 to 5 percent, azelaic acid 15 to 20 percent, and Kligman-style triple therapy (hydroquinone 4 percent, tretinoin 0.05 percent, fluocinolone 0.01 percent) in short courses with pauses.
For PIH: tretinoin or adapalene nightly, azelaic acid 10 to 15 percent daily, vitamin C in the morning, tranexamic acid topical. Treat the underlying acne aggressively to prevent new PIH. Patience is part of the protocol; 12 to 24 weeks for noticeable change in moderate cases.
What doesn’t work
Brightening serums alone for melasma. Vitamin C and niacinamide help around the edges; they don’t move the needle on the underlying hormonal driver. Hydroquinone used continuously for over six months. Ochronosis is a rare but irreversible side effect.
Aggressive chemical peels in dark skin tones. The inflammation from a poorly chosen peel can create more PIH than it removes. TCA peels above 20 percent in Fitzpatrick V-VI require very specific expertise.
Tool: home chemical peel guide — by % and skin type, with stop-signs.
Sun avoidance only in summer. Melasma patients lose ground in winter too if SPF is dropped. Visible light passes through clouds. Pigment-friendly habits run 12 months.
Lemon juice. Apple cider vinegar. Hydrogen peroxide. Each of these causes inflammation and risks PIH on top of the existing pigmentation.
When to see a dermatologist
Pigmentation that doesn’t fade with consistent topical care over six months. Suspected melasma during pregnancy or hormonal transitions. Any pigmented patch with irregular borders that might be lentigo or early melanoma. Dramatic pigment changes without clear inflammatory trigger. PIH that’s spreading rather than fading.
A derm can confirm the diagnosis, often with a Wood’s lamp examination, prescribe tranexamic acid orally, run lab work before starting it, and refer to appropriate laser specialists. In deeper skin tones, working with someone experienced in skin of color is meaningfully different from generic dermatology.
Tool: DPN triage — small dark papules on the cheekbones and temples in melanin-rich skin — removal options ranked by PIH risk.
For related context, see our coverage of melasma, hyperpigmentation, and the skin of color overview. The skin of color tag hub collects routines and product reviews calibrated for deeper phototypes.
FAQ
Can melasma ever fully clear? Sometimes during postpartum or after stopping hormonal contraception. Often it manages rather than resolves.
How long does PIH take to fade? Three to 18 months depending on phototype and treatment consistency. Deeper skin tones take longer.
Is tranexamic acid safe long-term? Generally yes, with monitoring. Contraindicated in patients with clotting disorders.
Can I use vitamin C and azelaic acid together? Yes. They work through different mechanisms. Many of my readers stack them in different parts of the day.
Will visible light matter even indoors? Some. Window glass blocks UVB but not all visible light. Iron oxide tinted SPF helps for sensitive cases.
Sources
Sheth VM, Pandya AG. Melasma: a comprehensive update. JAAD.org/” rel=”noopener” target=”_blank”>Journal of the AAD.org/” rel=”noopener” target=”_blank”>American Academy of Dermatology, 2011. Davis EC, Callender VD. Postinflammatory hyperpigmentation: a review of the epidemiology, clinical features, and treatment options in skin of color. Journal of Clinical and Aesthetic Dermatology, 2010. Taylor SC et al. Postinflammatory hyperpigmentation. Journal of Cutaneous Medicine and Surgery, 2009.