Post-inflammatory hyperpigmentation treatment is about restraint, not power. PIH is the brown or grey discoloration left after acne, a burn, a bug bite, or an over-aggressive laser session, and it responds best to sun protection, topical melanin control, and, when a device is used at all, a conservative low-fluence laser toning approach. Push the energy too high and you make the pigment worse. This guide covers PIH causes, safe settings, patient selection by skin type, and the adjuncts that carry most of the result.
Last reviewed: June 2026.
What is post-inflammatory hyperpigmentation and what causes it?
Post-inflammatory hyperpigmentation is excess melanin deposited in the skin after an inflammatory event. Any insult that irritates the skin can trigger it: acne, eczema, friction, a burn, aggressive chemical peels, or a laser or IPL treatment set too hot. The HONKON skin disease atlas in our knowledge base describes PIH as pigmentation that appears on the skin during or after acute or chronic inflammation, ranging from brown to almost black, showing as a patch or spot depending on the shape of the original inflammation.
Two features make PIH clinically distinct from a birthmark or a sun spot. First, it is driven by strengthened melanocyte activity in the basal layer of the epidermis, so it follows the footprint of whatever inflamed the skin. Second, it has a self-healing tendency: left alone and protected from the sun, many cases fade slowly on their own. That natural fading is exactly why a cautious, do-no-harm approach usually beats an aggressive one.
Why does over-treatment make PIH worse?
PIH is unusual among pigment problems because the treatment meant to fix it is also one of its most common causes. Excess heat re-inflames skin that is already primed to overproduce melanin, and the knowledge base is blunt about the risk: the listed complication of laser treatment for PIH is an increase in the pigmentation degree after treatment. In other words, the wrong settings do not just fail, they can darken the very mark you were asked to lighten.
This is why practitioners treating PIH lean on low fluence rather than high fluence. The principle traces back to selective photothermolysis, described by Anderson and Parrish in Science in 1983: energy should be delivered in pulses short enough to confine heat to the pigment target instead of spreading it into surrounding tissue. For PIH the additional rule is to keep total energy modest so the skin is nudged, not injured. Several gentle passes over a course of sessions are safer than one heavy pass.
One conservative session too few is a minor delay. One aggressive session too many can convert a fading mark into a stubborn one.
What are safe laser settings for PIH?
The safest device approach to PIH is low-fluence Q-switched 1064nm laser toning, delivered in multiple light sessions rather than a few strong ones. The 1064nm wavelength penetrates more deeply and is absorbed less by surface melanin than shorter green wavelengths, which makes it more forgiving in darker skin. Our knowledge base notes that high repetition rate, low energy density 1064nm light is associated with a gradual, subtle refinement of the skin rather than an abrupt ablative effect, which is the behaviour you want when the goal is to coax pigment down without provoking inflammation.
Concrete numbers for fluence, spot size, and pulse count depend on the specific device, the handpiece, and the lesion, so they must come from your machine's manual and your own conservative titration, not from a blog. What does transfer across devices are these operating principles:
- Choose 1064nm over 532nm for PIH in anything but very fair skin; reserve 532nm for superficial epidermal pigment in light skin only.
- Start at the low end of the energy range and treat to a mild, even warmth or faint erythema, never to whitening, frosting, or pinpoint bleeding.
- Use a larger spot and keep passes even; overlapping stacked pulses concentrate heat and invite rebound pigment.
- Space sessions weeks apart so any subclinical inflammation fully resolves before the next pass.
- Stop and reassess if the area darkens between sessions rather than lightening.
Our Q-switched Nd:YAG laser platform is built around this dual-wavelength 1064nm and 532nm design, and the low-fluence 1064nm toning mode is the relevant one for cautious PIH work.
How do you select patients by skin type?
Skin type drives every decision in PIH, because the darker the skin, the higher the melanin load and the greater the risk of provoking more pigment. The knowledge base sets out a clear escalation of caution across the Fitzpatrick scale: lighter skin types tolerate higher energy density, while darker types call for longer wavelengths, longer pulse durations, reduced output energy, and active cooling. Applied to PIH, that guidance points to a defensive posture in exactly the patients who present with PIH most often.
| Fitzpatrick type | PIH risk profile | Practical approach |
|---|---|---|
| I to II (fair) | Lower melanin, lower rebound risk | Can tolerate higher energy density; topical-first still preferred |
| III (medium) | Moderate risk, common PIH presentation | 1064nm low fluence, conservative titration, strict photoprotection |
| IV to VI (deep) | High melanin, high rebound risk | Longer wavelength, lower energy, active cooling; prioritise topicals, use devices sparingly |
Beyond skin type, screen for active inflammation. If the acne or dermatitis that caused the PIH is still flaring, treating the pigment first is putting the cart before the horse. Control the source, let the skin calm, then reassess. For a fuller treatment framework, see our post-inflammatory pigmentation solution page.
What is the conservative treatment sequence?
The knowledge base is explicit that the key treatment for PIH is to control the inflammation, not to fire a laser. Topical and behavioural measures do most of the work, and any device sits at the end of the line as an optional accelerator. A defensible sequence looks like this:
- Treat the underlying cause first. Get the acne, eczema, or dermatitis under control so no new pigment is being generated.
- Enforce strict sun protection. The atlas lists avoiding sun exposure as a core step, and PIH is documented to vary with sunshine and season, so broad-spectrum daily protection is non-negotiable.
- Start topical melanin control. The knowledge base references topical hydroquinone as an established option; modern practice also uses agents such as azelaic acid, retinoids, and others. Follow current label and regional regulations.
- Give topicals and time a real chance. Because PIH tends to self-resolve, weeks to months of conservative care often clears it without any device.
- Only then consider low-fluence laser toning, for residual or slow-to-fade pigment, in a suitable skin type, at conservative settings.
According to a comprehensive PIH overview published in the Journal of the American Academy of Dermatology, first-line management centres on identifying and treating the underlying inflammation combined with topical agents and broad-spectrum sun protection, with procedural options considered later. That ordering matches the knowledge base and should anchor how you counsel patients: devices are the last lever, not the first.
Which adjuncts support laser results?
Adjuncts are not optional extras in PIH; they are what protect and extend any device result. The single most important one is photoprotection, because unprotected sun exposure reactivates melanocytes and can undo weeks of progress in days. Pair daily broad-spectrum sunscreen with topical melanin management throughout the treatment course and for a sustained period afterward.
- Daily broad-spectrum sunscreen, reapplied, as the foundation of every PIH plan.
- Topical depigmenting agents such as hydroquinone or azelaic acid, per current regulations, to lower baseline melanin production.
- Barrier repair and gentle skincare, since irritation from harsh actives can itself trigger fresh PIH.
- Patience and spacing, allowing full recovery between any device sessions so inflammation never stacks.
If you are comparing our device options for pigment work, the guide to choosing a Q-switched Nd:YAG laser walks through wavelengths, handpieces, and use cases in more detail.
Frequently Asked Questions
Can laser make post-inflammatory hyperpigmentation worse?
Yes. The documented complication of laser treatment for PIH is an increase in pigmentation after treatment. PIH forms in response to inflammation, and excess laser heat re-inflames the skin, so overly aggressive settings can darken the mark rather than lighten it. This is why low-fluence toning across several gentle sessions is preferred over a few high-energy passes, especially in darker skin.
How many sessions does PIH usually need?
There is no fixed number. Because PIH often fades on its own with sun protection and topical care, many cases need no device at all. When laser toning is used, results build gradually over a course of conservatively spaced sessions rather than appearing after one treatment. The exact count varies with skin type, lesion depth, and how well the patient protects the area from the sun between visits.
Is 1064nm or 532nm better for PIH?
For most PIH, 1064nm is the safer choice. It penetrates more deeply and is absorbed less strongly by surface melanin, which lowers the risk of provoking more pigment in medium to dark skin. The 532nm wavelength targets superficial epidermal pigment and is better reserved for very fair skin. A dual-wavelength Q-switched platform lets the practitioner match the wavelength to the patient.
Should I treat PIH while acne is still active?
No. The core rule is to control the inflammation first. If acne or another inflammatory condition is still flaring, new pigment is still being generated, so treating the existing marks is premature. Calm the underlying condition, protect from the sun, start topical care, and reassess the residual pigment once the skin is stable before considering any device.
Written by the Pmise Technical Team. Pmise manufactures laser and light-based aesthetic systems and draws on device manuals and clinical training material spanning Q-switched Nd:YAG, fractional, and IPL platforms. This article is educational and is not a substitute for a qualified clinician's judgement.
