You've noticed dark spots on your skin after a laser procedure, inflammation, or a summer in the sun. The appearance is similar - an area darker than your natural skin tone, with more or less defined edges - but the cause, behavior over time, and response to treatment can be completely different.
PIH and melasma are two of the most common forms of acquired hyperpigmentation, often confused even by skincare professionals. Distinguishing between them doesn't require a clinical diagnosis: all it takes is a few targeted questions, an understanding of the mechanisms that generate them, and a careful examination of how they appear on your skin.
This guide is meant to help you navigate your way—not to replace the advice of a dermatologist, but to help you arrive at a consultation (or product choice) with a clearer understanding of what you're dealing with.
What they are and how they form
PIH - post-inflammatory hyperpigmentation
PIH (post-inflammatory hyperpigmentation) is a skin response to an inflammatory event. Whenever skin tissue is subjected to stress - whether from a laser procedure, acne, abrasion, or an allergic reaction - melanocytes in the affected area can increase melanin production as a defensive reaction.
The result is a darker area that appears after the inflammation has resolved. It's not strictly speaking permanent damage: in most cases, with consistent sun protection and the right approach, PIH tends to regress over time. How long this takes depends on the depth of pigmentation, skin type, and the sun exposure the skin has been exposed to in the meantime.
Darker phototypes (IV–VI according to the Fitzpatrick scale) are more predisposed to PIH and generally present longer regression times, due to a higher density of melanocytes and a more intense inflammatory response.
Among the most common triggers are laser hair removal, photorejuvenation, fractional CO₂ laser, acid treatments, inflammatory acne, and insect bites. To learn more about the specific mechanism associated with laser procedures, you can read the article dedicated to post-laser hyperpigmentation.
Melasma - hormonal and photoinduced hyperpigmentation
Melasma has a different nature. It doesn't arise from a single localized event, but from chronic activation of melanocytes in response to hormonal factors and UV exposure.
Estrogens - endogenous or exogenous, such as those found in oral contraceptives - increase the sensitivity of melanocytes to ultraviolet light, leading to widespread and persistent melanin production. This is why melasma is more common in women of childbearing age, during pregnancy, or after starting hormone therapy.
Unlike PIH, melasma tends to have a dermal component (in addition to the epidermal one), which makes it more resistant to treatment. It doesn't spontaneously regress over time unless the triggers are removed and even then, the sun is enough to cause it to recur.
5 questions to understand what type it is
These questions are not a substitute for a dermatological diagnosis, but they help you understand your situation in a more structured way.
Question 1: Did the spots appear after a procedure or inflammation?
If you can pinpoint a specific event - a laser treatment, an acne breakout, a burn, a skin reaction and the spots appeared in that exact area over the next few weeks, it's almost certainly PIH.
Melasma, on the other hand, develops gradually, often over months or years, without a single identifiable trigger. Those with melasma rarely remember the exact moment it appeared: "It was there before," or "it got worse this summer."
Answer "yes, after a specific event" → indicates PIH. Answer "I don't remember a specific event" → indicates melasma.
Question 2: Are the spots distributed symmetrically?
Melasma almost always follows a bilateral and symmetrical pattern: the same areas darken on both sides of the face, creating a mirror-like effect. The most affected areas are the cheeks, forehead, upper lip, and chin - the so-called "butterfly pattern."
PIH, on the other hand, is by definition localized: it follows the distribution of the inflammation or the procedure that caused it. If the laser treated an asymmetrical area, the spot will be asymmetrical. If the acne was concentrated on one side, the pigmentation will be more intense on that side.
Simmetrica e bilaterale → indica melasma.
Asimmetrica o localizzata in una zona specifica → indica PIH.
Question 3: Does pigmentation get worse rapidly in the sun?
Both conditions worsen with sun exposure - in this respect, they are similar. The difference lies in the speed and intensity of the response.
Melasma reacts rapidly and markedly to the sun: even a few days of exposure without adequate protection can cause visible deterioration. This happens because melanocytes are already in a state of chronic hyperactivity, and UV light is sufficient to intensify their production.
PIH also responds to the sun, but more gradually. The main problem is that UV rays slow down the natural regression of the spot: they don't necessarily darken it further quickly, but they prevent it from lightening.
Rapid and marked worsening in the sun → more typical of melasma. Slow regression or stagnation with the sun → typical of PIH.
Question 4: Have you had any recent hormonal changes?
Pregnancy, starting or switching oral contraceptives, hormone replacement therapy, and menstrual cycle changes: these factors are closely linked to melasma and almost irrelevant to PIH.
If the spots appeared or intensified in conjunction with a hormonal change - even if not immediately, but over the following months - the likelihood that they are melasma increases considerably.
Current or recent hormonal changes → indicates melasma. No identifiable hormonal changes → more likely PIH.
Question 5: How long ago did the spots appear?
PIH has a time window linked to the event that triggered it: it appears in the weeks following inflammation and, under favorable conditions (constant sun protection, use of appropriate active ingredients), tends to clear over the course of months. The timeframe varies from 3 months to 2 years depending on the skin type and the depth of pigmentation.
Melasma has no time frame: it can be present for years, tends to fluctuate with the seasons (worsening in summer, fading in winter), and does not regress spontaneously.
Recent spots, appearing after an event, tending to fade → PIH. Chronic spots, seasonal fluctuations, resistance to treatments → melasma.
Where they appear: the typical areas
Anatomical distribution is one of the most useful indicators.
PIH appears exactly where the inflammation or procedure occurred. After laser hair removal on the legs or armpits, the spots will be in those areas. After laser treatment on the face, they will follow the treatment plan. After acne, they will be in the areas where the lesions were present.
Melasma, on the other hand, has a predictable pattern: almost always limited to the face, with a predilection for the cheeks (malar area), forehead, upper lip, and chin. In less frequent cases, it can also affect the neck and décolleté. Distribution is always bilateral.
If the spots are on the body, arms, or legs in an area that has undergone treatment, it's almost certainly PIH. If they're symmetrically distributed across the face without a specific trigger, melasma is the most likely scenario.
How they behave over time
This is perhaps the most important difference from a practical point of view.
PIH has the potential for spontaneous regression. If the skin is consistently protected from the sun and not subjected to new inflammation, the spot tends to gradually lighten. In light skin types (I–III), this process can be completed in 3–6 months. In darker skin types (IV–VI), it can take up to 18–24 months, and the risk of recurrence with further procedures is higher.
Melasma is a chronic condition. Even when it subsides - thanks to a winter season and a lack of sun exposure - it tends to return during the first summer or with the first hormonal changes. Without active and ongoing management, it is unlikely to permanently regress.
What to do based on the type
If you have PIH post-laser procedure
The priority in the acute phase is to repair the skin barrier and reduce residual inflammation, conditions that, if left untreated, increase the risk of developing hyperpigmentation. Repairing products based on soothing ingredients, such as Epicalm Plus, are indicated in the post-laser recovery phase to support healing without overloading the skin.
Once the acute phase is over, the goal becomes to prevent and treat pigmentation. tranexamic acid It is currently one of the most studied active ingredients for PIH: it acts by interrupting the signal between keratinocytes and melanocytes which leads to the overproduction of melanin. Oleyl adapalenate, a third-generation retinoid, accelerates cell turnover with superior tolerability compared to classic tretinoin - an aspect particularly relevant for sensitive phototypes.
Sun protection is essential: without it, any pigmentation treatment loses its effectiveness. SPF 50 sunscreen for daily use it is the foundation on which to build any anti-PIH protocol.
For an integrated approach, Lumicor combines tranexamic acid, cetyl tranexamate mesylate, and oleyl adapalenate in a formulation specifically designed for the prevention and treatment of post-inflammatory hyperpigmentation, positioning itself as a modern alternative to traditional hydroquinone-based protocols.
If you have melasma
Melasma requires a more structured and long-term approach. Daily sun protection - even in the winter months and on cloudy days - is not optional: it's a prerequisite for any other treatment to be effective.
Depigmenting agents must be used consistently. Tranexamic acid has also proven effective in melasma, with a significantly superior safety profile to hydroquinone—banned in cosmetics in Europe since 2001. If you'd like to delve deeper into the comparison between therapeutic approaches, the article on protocol for treating melasma without hydroquinone offers a scientifically updated overview.
For those who have already used the Kligman's formula or are looking for a modern alternative, the combination of tranexamic acid with new-generation retinoids represents the most advanced standard in the cosmetic field today.
The tinted version of SPF - tinted sunscreen SPF 50 - can offer a double benefit for melasma: it protects from UV rays and, thanks to the iron oxides present in the dye, also filters high-energy visible light (HEV), which is able to stimulate melanogenesis independently of UV.
When to consult a dermatologist
This guide is intended to guide you, not replace a clinical evaluation. There are situations in which it is important to seek professional advice:
- The spots grow rapidly, change shape, or have irregular edges
- The color is uneven within the same spot (darker, lighter areas, reddish areas)
- Pigmentation does not respond to any treatment after 3–4 months of constant use
- The spots appear in atypical areas (palms of the hands, soles of the feet, mucous membranes)
- Do you have any concerns about a family history of melanoma or other skin conditions?
In these cases, dermatoscopy allows us to distinguish with certainty the different types of pigmentation and to exclude conditions that require medical attention.
Frequently Asked Questions
Does PIH go away on its own?
Yes, in most cases, PIH regresses spontaneously over time, provided the skin is consistently protected from the sun. The timeframe varies from a few months to over a year depending on the skin type and the depth of pigmentation. The use of targeted active ingredients can significantly accelerate the process.
Is melasma permanently curable?
Melasma is a chronic condition with a tendency to recur. It can be effectively managed with sunscreen and depigmenting treatments, but it is unlikely to resolve permanently without eliminating the triggering factors (sun exposure, hormonal imbalances). Many patients manage it with a consistent routine.
Can I use sunscreen on both conditions?
Yes, and it's not optional in either case: it's the cornerstone of any hyperpigmentation protocol. Without sunscreen, the effectiveness of any depigmenting agent is significantly reduced.
Can PIH and melasma appear together?
Yes. A person predisposed to melasma who undergoes a laser procedure may develop PIH in the treated area and melasma in the surrounding areas. In this case, the mechanisms overlap, and management requires a combined approach.
How do I know if my spot is superficial (epidermal) or deep (dermal)?
A basic empirical test: observe the spot under direct light - epidermal pigmentation appears clearer and more uniform, while dermal pigmentation tends to have blurred edges and a more grayish or bluish color. A definitive diagnosis, however, requires dermatoscopy or a Wood's lamp in a dermatology office.
Why the distinction is important
PIH and melasma are not the same thing, even if they superficially resemble each other. Confusing them risks choosing an approach that doesn't address the actual mechanism—and wasting months of treatment without results.
Knowing the nature of the dark spots you're dealing with allows you to build a more targeted routine, choose the right active ingredients, and have realistic expectations about how long it will take for them to improve. Sunscreen remains the essential starting point in both cases -everything else builds on top.
Scientific reference sources: Davis EC, Callender VD. Postinflammatory hyperpigmentation. J Clin Aesthet Dermatol. 2010; Ogbechie-Godec OA, Elbuluk N. Melasma: an Up-to-Date Comprehensive Review. Dermatol Ther (Heidelb). 2017; Passeron T et al. Melasma and photoprotection. J Am Acad Dermatol. 2013.