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OverviewAetiologyPathophysiologyClinical features and red flagsInvestigationsDifferential diagnosisManagementComplicationsMonitoring and follow-upSpecial situationsCommon pitfallsQuestionsSources
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Educational draft · awaiting clinical reviewThe full textbook explains uncertainty but does not replace live national or local guidance, specialist advice, or current prescribing information.

Melasma and post-inflammatory hyperpigmentation

Dermatology · UK scope · Sources checked 27 Aug 2026 · Clinical review pending

RapidFull

Overview

Distinguish patterned melasma from pigment left by inflammation, identify atypical or iatrogenic causes, and use slow, low-irritancy treatment that does not intensify dyschromia.

Melasma is a chronic relapsing facial hypermelanosis with symmetric macules and patches, usually over cheeks, forehead, upper lip and chin while sparing the vermilion. Pregnancy, combined hormonal contraception, family tendency and light exposure can precipitate or amplify it. Post-inflammatory hyperpigmentation is a reaction pattern: inflammation stimulates excess melanin production and transfers pigment into epidermis or dermis. It therefore follows the geography of acne papules, eczema plaques, burns, friction or a procedure rather than adopting a fixed facial template.

Colour should be described without using ethnicity as a diagnosis. Epidermal pigment tends to appear tan or brown; pigment-laden dermal macrophages can create slate-grey or blue-grey colour and clear slowly. In deeply pigmented skin, surrounding erythema may have been subtle or violaceous, so the patient may notice pigment before clinicians recognise the active inflammatory disease. Dermoscopy can show pigment network, perifollicular sparing and vascular clues, but history and distribution remain central.

Management protects against additional pigment while allowing gradual turnover. Broad-spectrum sunscreen, shade, hats and, where acceptable, tinted iron-oxide products can reduce ultraviolet and visible-light stimulation. Introduce one low-irritancy topical at a time, avoid unregulated skin-lightening products and review pregnancy potential before retinoids or hydroquinone. Cosmetic camouflage is a legitimate immediate intervention rather than evidence that the concern is trivial.

Key points

  • Melasma causes acquired symmetrical brown or grey-brown facial patches, commonly centrofacial or malar, influenced by ultraviolet and visible light, hormones and genetic susceptibility.
  • Post-inflammatory hyperpigmentation follows eczema, acne, infection, trauma, procedures or irritation and mirrors the sites and shapes of the preceding inflammatory process.
  • Both are more visible and often more persistent in richly pigmented skin; this reflects melanin biology and treatment response, not poor hygiene or inadequate care.
  • Take a timeline covering pregnancy, contraception, medicines, cosmetics, occupational exposure, inflammation and procedures before adding a pigment treatment.
  • Treat active dermatitis or acne first and use broad-spectrum photoprotection; repeated irritation from scrubs, peels or multiple active products creates more pigment.
  • Epidermal brown pigment generally improves faster than dermal blue-grey pigment, but Wood-lamp depth prediction is imperfect, particularly in darker skin.
  • Topical azelaic acid is an off-label pigment option with a favourable reproductive safety profile; hydroquinone and retinoid combinations require specialist oversight and strict pregnancy discussion.
  • Set expectations in months, not days. Relapse of melasma is common, and residual pigment can outlast successful control of the original inflammation.

Aetiology

01

Light and hormonal melasma

Ultraviolet and visible light interact with genetic susceptibility and hormonal states such as pregnancy or contraception to increase facial melanogenesis.

02

Inflammatory pigment signalling

Eczema, acne, infection, friction, burns and procedures release mediators that stimulate melanocytes and transfer excess pigment to surrounding keratinocytes.

03

Iatrogenic exposure

Irritant cosmetics, repeated peels and prolonged unregulated bleaching treatment can cause dermatitis, post-inflammatory darkening or exogenous ochronosis.

Pathophysiology

  1. 1
    Melanin production rises

    Activated melanocytes manufacture and distribute more melanin, darkening epidermis even after the initiating hormone or inflammation has settled.

  2. 2
    Pigment drops into dermis

    Basal-layer injury permits melanin to enter dermis, where macrophages retain it and create slower-clearing grey or blue tones.

  3. 3
    Light sustains signalling

    Ultraviolet and visible radiation maintain melanocyte activity and vascular or inflammatory signalling, helping explain melasma relapse after apparent clearance.

  4. 4
    Irritation restarts the cycle

    Barrier damage from aggressive treatment recruits fresh inflammation, so attempts to lighten skin can paradoxically increase pigment and prolong recovery.

Clinical features and red flags

Centrefacial symmetry

Bilateral macules coalesce over forehead, cheeks, upper lip or chin without scale, induration or surface destruction in typical melasma.

Inflammation-shaped pigment

Brown to slate patches correspond to previous acne, eczema, bites, burns, friction or procedures and may coexist with ongoing subtle inflammation.

Irritant amplification

Burning, scale and sharply applied borders after acids, retinoids, fragranced products or bleaching mixtures indicate treatment-induced inflammation worsening pigmentation.

Exogenous ochronosis

Blue-black reticulate darkening after prolonged hydroquinone or unregulated lightener exposure is paradoxical and requires dermatology review rather than stronger bleaching.

Atypical solitary lesion

Asymmetry, progressive colour variation, nodularity, ulceration or bleeding moves the problem out of a cosmetic pigment pathway and into lesion diagnosis.

Red flags requiring action

  • A single changing irregular pigmented lesion, mucosal or nail pigmentation, bleeding, ulceration, palpable infiltration, systemic illness or rapid unexplained diffuse pigmentation requires prompt diagnostic assessment rather than empirical lightening treatment.

Investigations

  1. 01
    Directed skin and product historyFirst step
    Why
    Separate patterned melasma, inflammatory pigment and an exposure-related reaction.
    Interpretation and limitations
    Link pigment to preceding redness, itch, acne, pregnancy, contraception, light, procedures and exact product ingredients; absence of recalled redness does not exclude subtle inflammation.
  2. 02
    Full skin examination and dermoscopy
    Why
    Confirm symmetry, surface state and benign pigment architecture while finding an active dermatosis.
    Interpretation and limitations
    Dermoscopy can support epidermal or dermal patterns and follicular sparing but cannot override evolving asymmetry or a melanoma feature.
  3. 03
    Wood-lamp examination
    Why
    Look for accentuation suggesting a predominantly epidermal pigment component.
    Interpretation and limitations
    Enhancement can guide expectations in lighter skin, but mixed pigment, topical residues and deeply pigmented skin limit depth classification and treatment prediction.
  4. 04
    Targeted endocrine or medicine assessment
    Why
    Investigate a supported hormonal, metabolic or drug cause of acquired pigmentation.
    Interpretation and limitations
    Pregnancy testing, thyroid or adrenal assessment follows symptoms and planned medicine; routine hormone panels do not diagnose ordinary melasma.

Differential diagnosis

01

Solar lentigines

Discrete sharply bordered macules on chronically exposed skin are less symmetrical and less confluent than the usual melasma field.

02

Lichen planus pigmentosus

Grey-brown facial or flexural pigmentation with a lichenoid pattern may need specialist examination and occasionally biopsy for distinction.

03

Drug or endocrine pigmentation

Diffuse or mucosal colour change with a medicine timeline or systemic features requires targeted pharmacological, adrenal, thyroid or nutritional assessment.

04

Pigmented skin cancer

A solitary evolving asymmetric lesion with irregular colours, bleeding or palpable change must be assessed independently rather than absorbed into a field diagnosis.

05

Exogenous ochronosis

Blue-black reticulate facial pigment after prolonged hydroquinone or unknown lightener use represents treatment injury and often resists ordinary bleaching.

Additional chapter-specific clues

Epidermal versus dermal colour

Brown pigment suggests a more superficial component, while blue-grey colour implies dermal melanophages and usually a slower response.

Management

01ClassifyFind the pigment trigger before treating colourFirst stepFacial or localised hyperpigmentation is the presenting concern.+
  1. 1Map distribution and colour, examine surface and compare current pigment with photographs and the shape of any preceding inflammatory eruption.
  2. 2Review pregnancy, hormonal contraception, systemic and topical medicines, cosmetics, peels, friction and occupational light or chemical exposure.
  3. 3Use dermoscopy and selective Wood-lamp examination, then biopsy or refer any solitary evolving, indurated, ulcerated or otherwise atypical lesion before applying a lightener.
02MelasmaReduce light stimulation and irritationSymmetrical facial patches and history support melasma without a concerning focal lesion.+
  1. 1Agree daily broad-spectrum sun protection, shade and hats; discuss tinted iron-oxide sunscreen where visible light is an important trigger and the formulation is acceptable.

Complications

01

Persistent dyschromia

Dermal pigment can remain for years and melasma commonly relapses, creating a chronic visible difference even after good trigger control.

02

Irritant or allergic dermatitis

Multiple active ingredients, fragrances and compounded treatments can inflame skin, interrupt adherence and create additional post-inflammatory pigment.

03

Exogenous ochronosis

Prolonged high-strength hydroquinone exposure can produce paradoxical blue-black dermal pigment deposition that is exceptionally difficult to reverse.

04

Psychosocial distress

Facial colour change may affect confidence, relationships and work, and deserves direct assessment rather than dismissal as a cosmetic concern.

Monitoring and follow-up

  • Take consented photographs in consistent light every two to three months, because daily mirror comparison exaggerates normal colour variation.
  • At each review ask about burning, scale, new darkening and the complete product list, including online lighteners, peels and home devices.
  • Track control of acne, eczema or other inflammation separately from fading of residual pigment so an effective anti-inflammatory plan is not abandoned early.
  • Review contraception and pregnancy plans before any retinoid, hydroquinone or procedure with reproductive restrictions.
  • Escalate a lesion that changes shape, colour, surface or symptoms even if it was initially labelled post-inflammatory pigmentation.

Special situations

Pigment remembers inflammation

Melanin can remain after redness, itch and scale resolve, so residual colour does not necessarily mean the original dermatosis is still active.

Irritation defeats lightening

An aggressive product may briefly exfoliate but inflammation stimulates new pigment, creating a cycle of burning followed by darker skin.

Visible light matters

Longer visible wavelengths can sustain melasma in darker phototypes, which is why tinted iron-oxide products may add benefit beyond ultraviolet filters.

Depth changes timescale

Epidermal melanin can leave with keratinocyte turnover, while dermal pigment depends on slower clearance from macrophages and may persist for years.

Camouflage is active care

A well-matched cosmetic product can restore confidence immediately while medical treatment works slowly or when biological response is incomplete.

Common pitfalls

  1. 01

    Calling every facial brown patch melasma without asking about preceding rash, products or an evolving focal lesion.

  2. 02

    Starting several acids, retinoids and lighteners together so the cause of irritation cannot be identified.

  3. 03

    Escalating strength when treatment-induced dermatitis is creating additional pigmentation.

  4. 04

    Using Wood-lamp findings as a guaranteed prediction of response in deeply pigmented skin.

  5. 05

    Prescribing or recommending hydroquinone without a time limit, pregnancy discussion and source-quality check.

  6. 06

    Assuming persistent colour means active acne or eczema has not been treated successfully.

Practice

Two practice questions

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Question 1 of 2
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DermatologyOriginal SBA

Symmetrical pregnancy-associated patches

A pregnant patient develops symmetrical, non-scaly brown patches over both cheeks and upper lip that deepen after light exposure. What is the most likely diagnosis?

Choose one answer, then submit
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Sources and review status3 sources · checked 27 Aug 2026 · clinical review pending+
Sources

Sources and review status

National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.

  • British Association of Dermatologists melasma informationClinical pattern, hormonal and light triggers, treatment and recurrence.
  • NHS sunscreen and sun safetyPractical broad-spectrum photoprotection and safe sun behaviour.
  • Skinoren 20% cream SmPCProduct dose and irritation safety; pigment treatment is off-label.

Editorial contact: Doctor’s Passport editorial team. Source-check date is separate from clinical approval. Report a content problem · Content changes

Authoring stateComplete draftClinical stateAwaiting reviewJurisdictionUnited Kingdom
  • 05
    Skin biopsy
    Why
    Resolve an atypical, infiltrated, treatment-resistant or diagnostically uncertain pigmented lesion.
    Interpretation and limitations
    Choose site with dermatology and communicate exposures and differential; biopsy itself can leave post-inflammatory pigment or a scar, which belongs in consent.
    • 2
    Review hormonal contributors without stopping effective contraception automatically, then introduce one tolerated topical option and a bland cleanser and moisturiser.
  • 3Assess photographs after several months, reduce any irritant regimen and explain that maintenance photoprotection is needed because relapse is frequent.
    • 03Post-inflammatory pigmentControl inflammation before fading its footprintPigment follows acne, eczema, infection, trauma, friction or a procedure.+
    1. 1Identify and treat the active cause with a regimen suitable for skin site, pregnancy status and infection risk, avoiding unnecessary trauma or picking.
    2. 2Use photoprotection and allow barrier recovery before adding azelaic acid or another low-irritancy pigment treatment one product at a time.
    3. 3Review whether colour is fading while watching for recurrent inflammation; stop agents that burn, scale or reproduce the original pigment pattern.
    04Refractory or complicatedEscalate safely to specialist treatmentEscalationPigment remains distressing, diagnosis is uncertain or previous lightening has caused adverse change.+
    1. 1Refer blue-black ochronosis, extensive dermal pigment, atypical lesions or failure despite a coherent low-irritancy plan to dermatology.
    2. 2Specialists may consider time-limited hydroquinone, retinoid combinations, chemical procedures or selected lasers after discussing off-label status, recurrence and pigment-change risk.
    3. 3Continue camouflage and psychological support during slow treatment and avoid presenting a procedure as a guaranteed or permanent colour correction.
    Key medicines and prescribing safety2 treatments · regimens, roles and cautions+
    An off-label pigment-modulating option that can also treat acne driving post-inflammatory hyperpigmentation.

    Azelaic acid 20% cream

    Apply a thin layer to affected facial skin twice daily after gentle cleansing; reduce to once daily or pause briefly if irritation is troublesome.

    Explain that pigmentation is an off-label indication. Avoid eyes and mucosa, introduce gradually on reactive skin and stop significant burning or dermatitis; improvement requires sustained use over months.

    Reduces melanin production in selected resistant epidermal melasma or post-inflammatory hyperpigmentation.

    Hydroquinone specialist pigment treatment

    Use only the dermatologist-selected unlicensed or compounded concentration, often once nightly for a strictly time-limited course with a documented stop date.

    Avoid pregnancy and breastfeeding unless a specialist determines otherwise; monitor irritant dermatitis and paradoxical exogenous ochronosis, and never obtain high-strength mixtures from unregulated sellers.