Melasma is one of the most challenging pigmentation presentations in aesthetic practice. It is also one of the most frequently mismanaged. I see patients who have been through multiple brightening treatments without lasting benefit. In many cases, the problem is not the treatment. It is the diagnosis.
Melasma and post-inflammatory hyperpigmentation look similar on a quick visual assessment. They require very different clinical approaches. Applying a PIH protocol to melasma produces a predictable outcome: temporary lightening, followed by rebound darkening, followed by a frustrated patient who has lost confidence in treatment.
How Melasma Differs from Post-Inflammatory Hyperpigmentation
Post-inflammatory hyperpigmentation follows an identifiable injury. A breakout, a burn, a procedure. It has a clear precipitating event and tends to be localised to the site of that injury. The colour is usually a flat, even brown, and it fades over months, faster with targeted treatment.
Melasma has a different origin. It is driven by a combination of ultraviolet exposure, genetic predisposition, and hormonal influence. It produces brown, grey-brown, or blue-grey patches distributed symmetrically across the face. The cheeks, upper lip, forehead, and nose bridge are the classic sites.
The symmetry is the key clinical marker. PIH follows the geography of the injury. Melasma follows a hormonal-UV pattern that mirrors across the face.
Hormonal triggers include pregnancy, the combined oral contraceptive pill, and hormone replacement therapy. Melasma develops during pregnancy in a significant proportion of women, sometimes called chloasma or the mask of pregnancy. It may persist long after the hormonal trigger has been removed, particularly with ongoing UV exposure. Some patients present with melasma that has persisted for years since their last pregnancy.
Clinical Assessment in Practice
A thorough trigger history is the foundation. In your consultation, ask about:
- Pregnancy history and current or past hormonal contraception or HRT
- The onset of the pigmentation relative to any hormonal change
- Sun exposure habits and whether the patches worsen in summer
- Any previous treatments and their outcomes
- Family history of pigmentation
A Wood's lamp examination helps determine depth. Epidermal melasma enhances under Wood's lamp illumination. Dermal melasma does not enhance. Mixed-type melasma shows partial enhancement. Depth is clinically significant: epidermal melasma responds better to topical treatment, while dermal melasma is substantially more resistant and warrants earlier dermatology referral.
Fitzpatrick skin type assessment is essential, and not only for safety planning. Melasma presents more commonly and with greater severity in Fitzpatrick types III to VI. The risk of post-inflammatory hyperpigmentation from over-aggressive treatment is substantially higher in these skin tones. This shapes every decision about which actives to use, at what strength, and which procedures are appropriate.
Baseline photography and MASI (Melasma Area and Severity Index) scoring create an objective baseline for tracking treatment response. Without this, both you and the patient are guessing at progress.
The Evidence Base for Treatment in the UK
Sun protection is not an adjunct to melasma treatment. It is the primary intervention. Without rigorous broad-spectrum SPF50+ applied daily, every other treatment will underperform or regress. This applies year-round in the UK, not only during the summer months. UV exposure sufficient to drive melanogenesis occurs on overcast days in winter. Patients who understand this are more compliant, because they understand the mechanism.
Topical tyrosinase inhibitors form the second pillar of treatment. Azelaic acid is well studied, available without prescription, and appropriate for most Fitzpatrick types with a good tolerability profile. Kojic acid at concentrations of 1 to 4% has a reasonable evidence base. Topical tranexamic acid has growing evidence in melasma, with systematic review data supporting meaningful reductions in MASI scores; it is also better tolerated than some older agents in darker skin tones.
Hydroquinone remains the most studied depigmenting agent globally. In the UK it is available on prescription only. Aesthetic practitioners without prescribing authority cannot supply it. Where it is indicated, referral to a prescribing practitioner or GP with dermatology interest is the appropriate pathway.
Chemical peels can support topical treatment in epidermal melasma when selected appropriately. The acid type, concentration, and frequency must account for Fitzpatrick type. Glycolic acid at lower concentrations has a reasonable safety record in Fitzpatrick III and IV. Aggressive peel protocols in darker skin tones carry a real risk of worsening the pigmentation you are treating through the mechanism of PIH. This must be communicated clearly before any peel, and written consent should reflect it.
Laser and light-based treatments for melasma require specialist-level caution. Certain wavelengths and fluences trigger rebound hyperpigmentation in melasma that is significantly harder to treat than the original presentation. This is not a niche risk. It is well documented. Where laser is being considered for a patient with melasma, referral to a practitioner with specific expertise in pigmentation is the appropriate step.
When to Refer
Refer to a dermatologist when:
- Wood's lamp suggests predominantly dermal or mixed-type melasma
- Three months of appropriate topical treatment has produced no measurable improvement
- The patient is pregnant or breastfeeding, where treatment options are significantly limited
- The presentation is atypical and the diagnosis is uncertain
Melasma can be confused with lichen planus pigmentosus, drug-induced pigmentation, Riehl's melanosis, and other conditions. When the clinical picture does not fit the classic melasma pattern, dermatology input protects the patient and your clinical reasoning.
Differential Diagnosis Is the Foundation
Accurate differential diagnosis between melasma, PIH, and other pigmentation conditions is what determines whether a treatment plan will work. Getting it right at the first consultation saves the patient from months of the wrong approach. The physical distribution, the trigger history, the Wood's lamp finding, and the Fitzpatrick assessment all sit within your scope. Use them.
If you want a structured clinical framework for pigmentation assessment that covers the full differential, Fitzpatrick risk stratification, and evidence-based treatment protocols, Hyperpigmentation Decoded is built for UK aesthetic practitioners at CPD level.