If you’re trying to figure out how to treat post-inflammatory hyperpigmentation without irritating skin, you’re likely already familiar with the frustration: the breakout or irritation is gone, but the dark mark lingers for weeks or months afterward.
Post-inflammatory hyperpigmentation (PIH) is one of the most common — and misunderstood — skin concerns. And while it’s tempting to reach for stronger and stronger “brightening” products, you risk increasing irritation; often what caused the discoloration in the first place.
Understanding how PIH forms, how long it lasts, and which ingredients actually help (at the right concentrations) is key to fading marks without making them worse.
What Is Post-Inflammatory Hyperpigmentation?
Post-inflammatory hyperpigmentation is discoloration that appears after the skin experiences inflammation or injury. It’s not a scar, and it’s not active acne; it’s the skin’s response after healing begins.
Common triggers include:
- acne breakouts
- eczema or dermatitis
- over-exfoliation
- irritation from strong actives or procedures
PIH can appear as pink, red, brown, or purple marks depending on skin tone and depth. While it’s harmless, it can be persistent, especially if the skin continues to be irritated.
How Does Post-Inflammatory Hyperpigmentation Form?
PIH starts with inflammation, not pigment.
When the skin becomes inflamed, it releases signaling molecules that stimulate melanocytes; the cells responsible for producing pigment. This is part of the skin’s protective response, but it can overshoot, leaving behind excess pigment long after the original issue resolves.
The more intense or repeated the inflammation, the stronger this signal becomes. That’s why aggressive treatments, picking at the skin, or layering too many actives often make PIH darker or longer-lasting.
In short:
Pigment is the result. Inflammation is the cause.
How Long Does Post-Inflammatory Hyperpigmentation Last?
The timeline for PIH varies widely.
- Mild PIH: may fade within a few weeks to a couple of months
- Moderate PIH: often lasts several months
- Deeper or recurring inflammation: can take a year or longer
Factors that slow fading include:
- repeated irritation
- sun exposure
- a compromised skin barrier
- introducing too many actives at once
This is why patience and consistency matter more than intensity when treating PIH.
Why Treating PIH Aggressively Often Backfires
Many people try to fade PIH by stacking exfoliating acids, high-percentage vitamin C, retinoids, and spot treatments all at once.
For sensitive or acne-prone skin, this approach often:
- disrupts the skin barrier
- triggers ongoing low-grade inflammation
- creates new PIH while trying to fade old marks
When the skin doesn’t feel calm, it continues sending pigment-producing signals. Progress stalls, or even reverses.
Treating PIH effectively means calming the skin first, then supporting gradual renewal.
Ingredients That Help Post-Inflammatory Hyperpigmentation
(And the Concentrations That Actually Matter)
Not all “brightening” ingredients work the same way. The most effective PIH strategies focus on reducing inflammation, supporting repair, and normalizing pigment signaling, not stripping the skin with harsh chemical exfoliants.
Allantoin (Optimal range: ~0.5–2%)
Allantoin is the active ingredient you will see listed in over-the-counter scar gels. It is a soothing, skin-repair ingredient that helps calm irritation and support healing. By reducing inflammation, it helps address the signal that drives excess pigment production in the first place.
At concentrations up to 2%, allantoin is particularly useful for sensitive skin types that can’t tolerate aggressive treatments but still want visible improvement over time.
(Night C.A.P. contains 0.5% allantoin)
Niacinamide (Optimal range: ~2–5%)
Niacinamide helps regulate pigment transfer within the skin while also supporting barrier function. Lower to moderate concentrations are often more effective long-term, as higher percentages can cause flushing or irritation for some people.
(Night C.A.P. contains 5% niacinamide)
Azelaic Acid (Optimal range: ~10–15% OTC / prescription strengths vary)
Azelaic acid is well-studied for post-acne marks because it helps calm inflammation and normalize pigment production. However, it can be drying or irritating if introduced too quickly or layered with too many other actives.
Tranexamic Acid (Optimal range: ~2–5%)
Tranexamic acid works by interrupting pigment signaling pathways. It’s often better tolerated than strong exfoliants and is commonly used in formulations designed for discoloration without irritation.
Vitamin C (Effective range varies by form)
Vitamin C is often recommended for post-inflammatory hyperpigmentation because it helps inhibit excess melanin production and supports overall skin brightness. However, not all vitamin C is the same — and tolerance depends heavily on the form and concentration.
- L-ascorbic acid, the most studied form, is typically effective around 10–20%, but it can be irritating for sensitive or compromised skin, especially when used daily.
- Vitamin C derivatives (such as sodium ascorbyl phosphate or magnesium ascorbyl phosphate) are generally better tolerated but may work more gradually and require consistent use.
For people prone to PIH, vitamin C can be helpful, but only when the skin barrier is healthy enough to tolerate it. Introducing high-strength vitamin C too early, or layering it with other strong actives, can trigger irritation that ultimately worsens discoloration rather than improving it.
When treating PIH, vitamin C tends to work best as a supporting ingredient, not the foundation of the routine.
Barrier-Supporting Ingredients That Matter
Supporting the skin barrier makes all pigment-fading strategies more effective. Ingredients like:
- ceramides
- cholesterol
- fatty acids
- colloidal oatmeal
help reduce reactivity and improve tolerance, allowing the skin to heal and marks to fade naturally.
(Night C.A.P. contains all of these barrier supporting ingredients)
What to Avoid When Treating PIH on Sensitive Skin
- daily exfoliation
- layering too many harsh actives in one routine
- chasing fast results at the expense of barrier health
- ignoring ongoing irritation or dryness
If your skin is constantly reactive, PIH has little incentive to fade.
A Gentle, Barrier-First Approach to Treating PIH
A sustainable approach to PIH focuses on:
- calming inflammation
- wearing sunscreen daily
- supporting barrier repair
- adding new actives slowly
This doesn’t mean doing nothing, it means doing less, more consistently.
Treat the Inflammation, Not Just the Pigment
Post-inflammatory hyperpigmentation fades when the skin feels stable again. When inflammation is reduced and the barrier is supported, pigment signals quiet down and marks gradually soften.
There’s no shortcut that works for everyone — but gentle, well-formulated routines tend to deliver the most reliable results over time.
If you’re dealing with PIH, the goal isn’t to fight your skin. It’s to help it recover.
