Short answer: Post-inflammatory hyperpigmentation, or PIH, is a flat brown, grey or darker mark left after acne, irritation, bites or another inflammatory event. It is pigment change rather than a textural scar. The most useful plan is to control the trigger, avoid picking and over-exfoliation, protect the area from ultraviolet exposure, and introduce one tolerated tone-support product at a time. Improvement is gradual and can take months.
Recognise PIH and its common triggers
PIH appears where inflammation previously occurred and is especially persistent in deeper skin tones. Acne, eczema, friction, shaving, burns and aggressive procedures can all leave residual pigment. A mark that changes shape, bleeds, grows without a preceding inflammatory event or looks unlike neighbouring spots should not be assumed to be PIH. Photography in consistent lighting can help track colour without relying on daily mirror changes.
Prevent new marks before chasing old ones
Treat the source of inflammation gently: do not squeeze blemishes, repeatedly scrub the same patch or combine several acids. Use broad-spectrum sunscreen on exposed areas and reapply when outdoors. Visible light can matter in some pigment disorders, but product choice and tint should be individualized. On the body, reduce friction from tight clothing or repetitive rubbing and moisturise dry skin before introducing exfoliation.
A conservative starting routine
- Gentle cleanse without brushes or gritty pressure.
- One tone-support treatment on intact skin.
- Moisturiser to maintain comfort and adherence.
- Broad-spectrum sunscreen on exposed areas.
Choose one active and set realistic expectations
Kojic acid, niacinamide and vitamin C products have different mechanisms and evidence bases. None can be ranked universally without comparing the actual concentrations, pH, packaging and complete formula. Introduce one product for several weeks, follow its directions and stop if irritation persists. Combining several brighteners immediately makes it difficult to identify benefit or intolerance and may increase the very inflammation that sustains PIH.
When professional assessment is useful
Seek dermatology advice when pigment is extensive, rapidly changing, associated with active acne or eczema, or unchanged despite a consistent gentle plan. Prescription options and procedures carry benefits and risks that differ by skin tone. PIH studies use varied interventions and outcome measures, so timelines are approximate. The goal of cosmetic care is gradual tone support while preventing recurrence, not bleaching natural skin colour.
Silouel products to consider
These currently published options are included for routine or ingredient relevance. Ingredient research does not prove that a Silouel finished formula will reproduce every result discussed in this article.
- Kojic + C Radiance Complex — a brightening serum whose current store record lists kojic acid plus vitamin C and vitamin E ingredients. Check the live product page and full INCI before use.
- Niamicide B3 Hydro Gel Complex — a lightweight gel whose current store record highlights niacinamide and hydration support. Check the live product page and full INCI before use.
- The Feluric Standard Radiance — a serum whose current store record specifies ascorbyl glucoside and ferulic acid alongside vitamin E and sea buckthorn oil. Check the live product page and full INCI before use.
Related reading
Frequently asked questions
Is PIH the same as an acne scar?
No. PIH is a flat colour change. Indented, raised or firm changes are scars and usually need a different assessment.
How long does PIH take to fade?
Superficial marks may improve over months, while deeper pigment can last longer. Skin tone, inflammation and sun exposure affect the timeline.
Can I use several brightening serums together?
It is safer and more informative to introduce one at a time. Multiple actives can increase irritation without guaranteeing faster results.
Does sunscreen remove existing spots?
Sunscreen is not a pigment remover, but it helps reduce further darkening and supports the rest of a tone-care plan.
Sources and evidence
- DermNet clinical overview
- PubMed-indexed paper or review 2
- PubMed-indexed paper or review 3
- American Academy of Dermatology guidance
Evidence boundary: PIH trials are heterogeneous and ingredient findings do not establish performance for an untested finished product; persistent or unclear lesions need diagnosis.
These sources support the educational discussion of ingredients, routines or conditions. They are not certificates of performance for any Silouel finished product.
