Facial hyperpigmentation: melasma, PIH, or sun spots?

Facial hyperpigmentation has several common causes that look similar but behave differently, and the three seen most often are melasma, post-inflammatory hyperpigmentation (PIH), and solar lentigines (often called age spots or sun spots) [1][2]. Telling them apart matters because the prognosis and the safe treatment differ: PIH is usually curable, melasma is chronic and relapsing and can be worsened by aggressive treatment, and solar lentigines are a sign of photoaging that persist until treated [1][3][4].

This article explains how clinicians distinguish these three conditions, why the distinction changes the treatment plan, and what the evidence supports for each. It is not medical advice; an accurate diagnosis should come from a board-certified dermatologist, who can also exclude less common or concerning causes of a pigmented spot.

Why the distinction matters

The overlap in appearance is real, but the conditions respond differently and even react in opposite directions to the same procedure. Melasma can flare after aggressive laser treatment, whereas a similar device may be appropriate for a solar lentigo [3][4]. Matching the approach to the diagnosis is what prevents a treatment from making pigmentation worse, which is a common and avoidable outcome.

Melasma

Melasma is an acquired, often symmetric pattern of brown to grey-brown patches, typically across the cheeks, forehead, upper lip, and chin. It predominantly affects women, is influenced by hormones and sun exposure, and is chronic and prone to relapse [3]. The evidence-based foundation is topical lightening therapy combined with strict sun protection; triple-combination cream and hydroquinone are the most-studied topical options, while chemical peels and laser or light devices give mixed results and carry a higher risk of adverse effects, including making the pigmentation worse [3]. Our triple-combination cream guide covers first-line topical therapy, and tranexamic acid is an emerging systemic adjunct.

Post-inflammatory hyperpigmentation

PIH is the flat brown or grey discoloration left behind after inflammation or injury, such as acne lesions, eczema, or a cosmetic procedure. Unlike melasma, it appears wherever the inciting inflammation occurred rather than in a symmetric facial pattern, and it can usually be cleared with topical therapy and time, particularly when the underlying cause is controlled [1]. Treating the source, for example active acne, is part of preventing new PIH. People with richer skin tones are more prone to PIH, which is why gentle treatment and sun protection matter most in skin of color [1].

Solar lentigines

Solar lentigines are well-defined flat brown spots that develop in chronically sun-exposed areas such as the face, the backs of the hands, and the shoulders, and they are an early sign of photoaging [4]. They are benign, but because a pigmented spot can occasionally mimic an early skin cancer, a new, changing, or atypical lesion should be evaluated before any cosmetic treatment. A systematic review of solar lentigines treatments found that laser and intense pulsed light therapies were generally more effective than other methods, with topical agents such as a mequinol-tretinoin combination also effective for facial lesions [4].

How clinicians tell them apart

Clinicians use the distribution, history, and sometimes dermoscopy or a Wood's lamp to classify the pigmentation before choosing treatment [1][2].

Shared foundation: sun protection and gentle care

Whatever the type, ultraviolet and visible light drive pigmentation, so daily broad-spectrum sun protection is the common foundation that makes other treatments effective and limits recurrence [3]. Gentle skin care and tyrosinase-inhibiting cosmeceuticals such as vitamin C, niacinamide, azelaic acid, and kojic acid are widely used as adjuncts across all three conditions [2]. Our photoprotection guide covers sun protection in detail.

Adverse events, limitations, and realistic expectations

• Misdiagnosis can worsen pigmentation. Treating melasma like a sun spot with an aggressive device is a recognized cause of rebound darkening [3].
• Melasma is managed, not cured. Maintenance and sun protection are needed long term, and relapse is common [3].
• Topical agents take time. Lightening usually requires weeks to months of consistent use, and irritation can itself trigger PIH [1][2].
• Procedure risk is higher in darker skin. Lasers, peels, and energy devices carry a greater risk of PIH in Fitzpatrick III to VI skin and need conservative settings [1][4].
• Exclude malignancy first. An atypical or changing pigmented lesion needs evaluation before any cosmetic treatment.

Bottom line

Melasma, post-inflammatory hyperpigmentation, and solar lentigines look alike but differ in cause, course, and safe treatment, so an accurate diagnosis comes first [1][3][4]. Topical lightening and strict sun protection anchor melasma and PIH, laser or light therapy is more central for solar lentigines, and aggressive procedures are used cautiously, especially in darker skin, to avoid worsening pigmentation. When a spot looks atypical or is changing, evaluation to exclude skin cancer takes priority over any cosmetic plan.

This article is for informational purposes and does not constitute medical advice.