Post-inflammatory hyperpigmentation (PIH) and melasma can both appear as brown, grey-brown or uneven areas of pigmentation. However, they do not develop for the same reasons and may require different treatment priorities.
PIH develops after inflammation or skin injury, such as acne, dermatitis, friction, picking or an irritating skincare treatment. The location of the pigmentation usually corresponds to the area where the inflammation occurred.
Melasma is a chronic and recurring pigmentary condition that most commonly appears as broader, often symmetrical patches on the cheeks, forehead, nose, upper lip or jawline. It is influenced by several factors, including ultraviolet and visible-light exposure, hormonal changes, genetics and melanocyte activity.
PIH and melasma can also occur together, which may make visual identification more difficult. Understanding the history, location, pattern and behaviour of the pigmentation is therefore important before choosing a treatment approach.
What Is Post-Inflammatory Hyperpigmentation (PIH)?
Common triggers include:
- acne lesions
- eczema or dermatitis
- picking, rubbing or friction
- burns or other skin injuries
- poorly tolerated skincare products
- chemical peels, lasers or other procedures that create excessive irritation
PIH usually appears in the same location as the previous inflammation. It may present as light brown, dark brown, grey-brown or, when pigment is deposited more deeply, blue-grey discolouration.
The marks are generally flat and may occur on the face or body. Existing PIH can remain visible after inflammation has resolved, while continuing acne or irritation may repeatedly create new areas of pigmentation.
What Is Melasma?
Melasma is a chronic and recurring pigmentary condition caused by increased melanin activity within affected areas of the skin. Unlike PIH, it does not require a previous acne lesion, rash or visible skin injury.
Melasma is influenced by a combination of factors, which may include:
- ultraviolet and visible-light exposure
- hormonal changes, including pregnancy
- oral contraceptives or other hormonal medications
- genetic predisposition
- skin tone and melanocyte responsiveness
- repeated heat exposure in some individuals
- irritation from unsuitable products or procedures
Melasma usually appears as flat, irregular areas of light brown, dark brown or grey-brown pigmentation. It commonly develops on both sides of the face in one of the following patterns:
- centrofacial: forehead, cheeks, nose and upper lip
- malar: cheeks and nose
- mandibular: jawline and chin
Melasma may become darker with sun exposure and can improve during some periods before becoming noticeable again. For this reason, treatment usually requires long-term management rather than expecting permanent pigment removal.
Key Clinical Differences Between PIH and Melasma
Although colour may look similar, the history and distribution of the pigmentation often provide important clues.
Previous Inflammation
- PIH: Usually follows acne, dermatitis, picking, friction, injury or an irritating procedure.
- Melasma: May develop without any previous visible inflammation or skin injury.
Pattern
- PIH: Often appears as individual marks or irregular patches corresponding to previous inflammatory lesions.
- Melasma: More commonly forms broader patches and often appears on both sides of the face.
Location
- PIH: Can occur anywhere on the face or body where inflammation or injury has occurred.
- Melasma: Most commonly affects the cheeks, forehead, nose, upper lip, jawline or chin.
Course
- PIH: May gradually fade when the original inflammation is controlled and no new injury occurs.
- Melasma: Tends to be chronic and recurring. It may improve and then darken again following light exposure, hormonal changes or irritation.
Treatment Priority
- PIH: Treatment begins by controlling the inflammatory trigger and preventing new marks.
- Melasma: Management focuses on long-term pigment regulation, consistent light protection and avoiding factors that repeatedly reactivate pigmentation.
These patterns are helpful, but they are not absolute rules. PIH can occur symmetrically, melasma may be more noticeable on one side, and both conditions can be present in the same area.
Can PIH and Melasma Occur Together?
Yes. A person with melasma can also develop PIH from acne, dermatitis, picking, friction or an irritating skincare treatment. Localized post-inflammatory marks may then appear over or beside broader areas of melasma.
This overlap can make the pigmentation look darker, more irregular or more difficult to classify. It may also occur when aggressive treatment intended to lighten melasma creates new irritation and triggers additional PIH.
The clinical image below shows a mixed presentation with broader melasma-like pigmentation, localized post-inflammatory discolouration and small bumps resembling syringomas. However, an image alone cannot confirm each condition.
When melasma and PIH may be present together, treatment should not begin by aggressively targeting all visible pigment. Active irritation must be controlled, the skin barrier should be stabilized and pigment treatment introduced gradually according to skin tolerance.
Why Appearance Alone May Not Confirm the Condition
PIH and melasma cannot always be distinguished by colour alone. Both may appear brown, grey-brown or uneven, and their appearance can vary according to skin tone, pigment depth and previous treatment.
Note: In this clinical example, the client reported that she had lived for many years in a high-UV climate without regularly applying sunscreen. The pigmentation includes scattered sunspot-like areas and broader uneven discolouration. This demonstrates why pigmentation history and distribution must be considered rather than assuming that every brown facial patch is melasma.
A proper assessment considers:
whether acne, irritation or injury occurred first
whether the pigmentation matches previous inflammatory lesions
whether it appears on both sides of the face
when the pigmentation first developed
whether pregnancy or hormonal medication was involved
whether it becomes darker during sunnier seasons
which products or procedures have already been used
whether the pigmentation is flat or accompanied by a change in skin texture
A dermatologist may use clinical examination, dermoscopy or a Wood’s lamp as part of the assessment. However, these tools must be interpreted together with the person’s skin history and the visible pattern.
Medical assessment is especially important when a pigmented area is new, rapidly changing, raised, scaly, painful, itchy, bleeding or noticeably different from the surrounding marks. Not every area of facial pigmentation is PIH or melasma.
Why Correct Identification Changes Treatment
PIH and melasma may share some treatment principles, including consistent sun protection, gradual pigment regulation and prevention of irritation. However, their main treatment priorities are not identical.
When PIH is present, the original inflammatory trigger must be identified and controlled. Treating the remaining pigment while acne, dermatitis, picking or product-related irritation continues may result in new marks forming faster than older marks can fade.
Melasma requires long-term management because melanocyte activity can be repeatedly stimulated by ultraviolet and visible light, hormonal influences and individual predisposition. Pigmentation may return even after noticeable improvement.
If melasma is treated as a simple isolated dark spot, temporary fading may be followed by recurrence. If PIH is treated without controlling the underlying inflammation, new areas of pigmentation may continue to develop.
Strong peels, aggressive exfoliation, poorly selected lasers or several active ingredients introduced at once can irritate the skin and worsen either condition. The safest approach is based on the cause, pattern, pigment depth, skin tone and treatment tolerance—not only on how dark the pigmentation appears.
Clinical Insight
One of the most useful clinical clues is the relationship between the pigmentation and the person’s skin history.
Individual marks that correspond closely to previous acne lesions, irritation or injury are more consistent with PIH. Broader pigmentation that develops on both sides of the face, returns after improvement and becomes more noticeable with light exposure may be more consistent with melasma.
However, mixed pigmentation is common. A person may have melasma across the cheeks while also developing PIH from acne, picking or irritating products in the same area.
This is why every brown mark should not be treated in the same way. Focusing only on visible colour—without considering inflammation, distribution, recurrence and skin-barrier condition—can lead to slow improvement or worsening pigmentation.
Key Takeaway
PIH develops after inflammation or skin injury, while melasma is a chronic and recurring pigmentary condition influenced by light exposure, hormonal factors, genetics and melanocyte activity.
PIH often corresponds to the location of previous acne or irritation. Melasma more commonly appears as broader, often symmetrical facial pigmentation. However, both conditions may occur together and cannot always be identified by colour alone.
Effective management begins with understanding the cause, pattern and behaviour of the pigmentation. Treatment should be gradual, well tolerated and adjusted to the individual skin condition. When the diagnosis is uncertain or the pigmentation changes unexpectedly, professional medical assessment is recommended.
Related Reading
- What Is PIH?
- Why Does PIH Last So Long?
- How to Treat PIH Correctly
- PIH vs PIE: Understanding Post-Acne Marks
- Sun Damage and Pigmentation in Different Skin Tones
- PIH Hub
Medical Esthetician (18 years of experience)
Skin Logic by Angelina
