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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.

Keratosis pilaris

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

RapidFull

Overview

Recognise benign follicular keratin plugging, distinguish it from inflammatory, infective and nutritional mimics, explain its fluctuating natural history and offer proportionate moisturising or keratolytic care without promising cure.

Keratosis pilaris is a common variation of follicular keratinisation. Examine outer upper arms, thighs, cheeks and buttocks for uniform 1–2 mm plugs and assess background dryness or eczema. Palpation is central: in richly pigmented skin the rough follicular surface may be clearer than redness, while hyperpigmented dots can remain after inflammation. Pustules, marked tenderness and drainage point elsewhere.

A confident clinical explanation is often the main intervention. The bumps are harmless, cannot spread to another person and commonly fluctuate with age and season. Ask whether texture, itch, pigment or appearance is the priority. Some people prefer no treatment after reassurance; others want a time-limited trial that does not create worse dermatitis than the original condition.

Begin with gentle washing and a bland emollient. If roughness remains troublesome, add one keratolytic product such as urea, lactic acid or salicylic acid to a small area and build slowly. Use product-specific age, pregnancy, area and concentration instructions. Stronger topical retinoids or procedural approaches are off-label specialist considerations with limited durability, not routine first-line care.

Key points

  • Keratosis pilaris produces many small rough follicular plugs, classically on the outer upper arms and thighs and sometimes cheeks or buttocks.
  • Lesions are usually symmetrical and feel like permanent gooseflesh; colour may be skin-coloured, pink-red, violaceous or brown depending on inflammation and skin tone.
  • It is common, benign, non-contagious and not caused by poor hygiene; no routine blood test, swab or biopsy is needed for a typical presentation.
  • The condition often worsens with dry winter skin and may improve with age, but treatment controls texture rather than removing the inherited tendency permanently.
  • A fragrance-free emollient applied at least daily, especially after bathing, is the lowest-risk first step for dryness and roughness.
  • Urea, lactic acid or salicylic-acid products can soften plugs, but introduce one product gradually and stop if burning or dermatitis develops.
  • Avoid picking, abrasive scrubs and aggressive loofahs because trauma increases inflammation, hyperpigmentation and occasional scarring.
  • All paraffin-containing and paraffin-free emollient residue on clothing and bedding can increase fire intensity; keep away from flames, cigarettes and naked heat and wash fabrics regularly.

Aetiology

01

Inherited follicular keratinisation

A common polygenic tendency causes keratin to accumulate at follicular openings; family history is frequent and onset often occurs in childhood.

02

Atopic and dry-skin association

Keratosis pilaris is more frequent with eczema, ichthyosis vulgaris and generally dry skin, although affected people need not have another disorder.

03

Seasonal barrier change

Low humidity and winter heating increase surface dryness and roughness, while some people improve in warmer, more humid conditions.

04

Physiological persistence

The tendency often becomes prominent around puberty, may improve with age and is not caused by infection, dirt, allergy or inadequate exfoliation.

Pathophysiology

  1. 1
    Follicular keratin plug

    Excess cohesive keratin fills the upper hair follicle and produces a firm 1–2 mm conical bump with a central hair or plug.

  2. 2
    Perifollicular inflammation

    Mechanical irritation and trapped hair can create surrounding erythema or colour change, but ordinary lesions contain neither an abscess nor contagious pathogen.

  3. 3
    Dry surface amplification

    Reduced hydration makes plugs project and feel rougher, explaining why emollients can improve texture without permanently changing the inherited tendency.

  4. 4
    Pigmentary residue

    Inflammation, squeezing and harsh scrubbing can leave persistent hyperpigmented macules, particularly in darker skin, even after the bump flattens.

Clinical features and red flags

Extensor follicular roughness

Numerous uniform keratotic bumps sit at hair follicles over posterolateral upper arms or anterior thighs and feel rough when a hand passes over them.

Central plug or curled hair

Magnification may show a tiny keratin spine or coiled hair in the follicular opening without a true comedonal blackhead.

Seasonal dry-skin context

Texture often becomes more obvious in winter alongside xerosis or atopic eczema and softens during humid weather.

Skin-tone variation

Perifollicular inflammation can appear red, violet, grey-brown or predominantly as hyperpigmented dots, while the tactile plug remains consistent.

Benign symptom profile

Ordinary lesions are asymptomatic or mildly itchy and neither painful nor purulent; systemic health is unaffected.

Atypical systemic patternRed flag

Bleeding gums, easy bruising, corkscrew hairs, severe dietary restriction or rapidly generalised hyperkeratosis requires urgent nutritional and medical assessment.

Red flags requiring action

  • Pain, pus, fever, rapid spread, blistering, scarring hair loss, nail or mucosal change, erythroderma, bleeding perifollicular lesions or dietary and systemic features suggesting nutritional deficiency requires diagnostic reassessment.

Investigations

  1. 01
    Clinical morphology and distribution examinationFirst step
    Why
    Confirm typical uniform follicular plugging and exclude pustular, comedonal or scarring disease.
    Interpretation and limitations
    Symmetrical extensor roughness without pain or pus is usually sufficient; photograph only with consent when it aids monitoring.
  2. 02
    Atopy and skin-care history
    Why
    Identify eczema, xerosis and irritant practices that alter treatment tolerance.
    Interpretation and limitations
    Treat coexisting eczema as eczema and reduce abrasive products; an atopic history supports association but is not required for diagnosis.
  3. 03
    Dietary and systemic assessment when atypical
    Why
    Detect vitamin C, vitamin A or broader nutritional deficiency when red flags accompany follicular hyperkeratosis.
    Interpretation and limitations
    Laboratory tests follow the dietary and systemic phenotype; do not screen well patients with lifelong typical extensor bumps.
  4. 04
    Microbiology for true pustules
    Why
    Evaluate bacterial or yeast folliculitis when purulence, crust or infection exposure is present.
    Interpretation and limitations
    A dry keratin plug is not a pus specimen; sample a fresh pustule only when the morphology genuinely supports infection.

Differential diagnosis

01

Folliculitis

Tender pustules, crust, spreading inflammation or a microbial exposure favour infectious folliculitis; keratosis pilaris is dry, uniform and non-purulent.

02

Acne vulgaris

Open and closed comedones with papules on face, chest or back differ from the small uniform extensor-arm plugs of keratosis pilaris.

03

Atopic eczema

Confluent itchy inflamed patches, excoriation, lichenification and flexural distribution support eczema, although follicular keratosis and eczema frequently coexist.

04

Phrynoderma or scurvy

Sudden widespread follicular hyperkeratosis with dietary restriction, bleeding gums, corkscrew hairs, bruising or systemic illness requires nutritional assessment.

05

Inflammatory or scarring follicular disorder

Scalp involvement, alopecia, atrophy, prominent scale, pustules, nail change or progressive scarring is not routine keratosis pilaris and may require biopsy.

Management

01Typical benign diseaseExplain and offer no-treatment choiceFirst stepUniform asymptomatic extensor follicular plugs occur without infection, scarring or systemic features.+
  1. 1Name the condition, explain inherited follicular plugging and its non-contagious, medically harmless and fluctuating nature, and ask what outcome matters.
  2. 2Offer gentle cleansing, avoidance of picking and at least daily fragrance-free emollient after bathing, including clear fire-safety advice for contaminated fabrics.
  3. 3Review only if desired or if morphology changes; no routine laboratory test, antibiotic or specialist referral is necessary.
02Troublesome textureTrial one keratolytic carefullyRoughness or visible plugging remains important despite moisturising and the person wants active treatment.+
  1. 1Choose one urea, lactic-acid or salicylic-acid preparation suited to age, body area, pregnancy context and background eczema, and test a small area.

Complications

01

Persistent pigment change

Picking, friction or irritant acids can cause prolonged post-inflammatory hyperpigmentation that is more troublesome than the original texture.

02

Irritant dermatitis

Overuse of salicylic acid, lactic acid, urea or retinoids can produce burning, scale and eczema while worsening visible colour change.

03

Psychosocial concern

Although medically harmless, visible texture can affect clothing, confidence and body image; reassurance should validate rather than dismiss that impact.

04

Unnecessary antimicrobial exposure

Mistaking sterile plugs for folliculitis leads to antibiotics that neither smooth texture nor alter the natural history and may select resistance.

Monitoring and follow-up

  • Judge a treatment trial by the patient-prioritised outcome—texture, itch or appearance—rather than promising eradication of every follicular dot.
  • Check after six to eight weeks for burning, scale, eczema, increased hyperpigmentation and whether the chosen product is worth continuing.
  • Review technique and concurrent scrubs before escalating concentration; mechanical and chemical over-exfoliation commonly create the apparent worsening.
  • Reassess if lesions become painful, pustular, asymmetric, rapidly widespread, scarred or associated with hair, nail, mucosal or systemic change.
  • Repeat emollient fire-safety advice: residue in clothing, dressings and bedding can accelerate ignition even when the product contains no paraffin.

Special situations

Touch can be more reliable than colour

The sandpaper-like follicular surface persists across skin tones even when perifollicular redness is absent or appears brown.

No-treatment is legitimate

Once the benign diagnosis is secure, choosing reassurance alone avoids turning a harmless variation into a burdensome medical regimen.

One acid at a time

Layering urea, salicylic acid, lactic acid and a retinoid increases dermatitis more predictably than it increases useful smoothing.

Texture returns

Keratolytics remove or soften current plugs but do not permanently reset inherited follicular keratinisation.

Emollient residue burns

Repeatedly impregnated fabric can ignite and burn intensely, so flame avoidance and regular washing belong in every emollient discussion.

Common pitfalls

  1. 01

    Prescribing antibiotics for dry sterile follicular plugs because the word follicular is mistaken for infection.

  2. 02

    Telling a patient to scrub harder and causing dermatitis, pigment change and excoriations.

  3. 03

    Promising a permanent cure from a keratolytic and labelling expected recurrence as treatment failure.

  4. 04

    Ignoring atypical purulence, pain, scarring or nutritional symptoms because the lesions initially resemble keratosis pilaris.

  5. 05

    Applying topical retinoid in pregnancy for a harmless condition with many safer or no-treatment alternatives.

  6. 06

    Forgetting that emollient-contaminated clothing remains a fire risk even after the cream has dried on skin.

Practice

Two practice questions

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Question 1 of 2
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DermatologyOriginal SBA

Rough outer-arm bumps

A healthy 16-year-old has symmetrical, painless rough follicular bumps on the outer upper arms that worsen each winter. There is no pus, scarring or systemic symptom. What is the best initial approach?

Choose one answer, then submit
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Sources and review status4 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 keratosis pilarisClinical pattern, natural history, emollient and keratolytic treatment.
  • NHS emollientsEmollient selection, application and fire-safety advice.
  • MHRA emollient severe and fatal burn riskAuthoritative fabric-contamination and fire-safety warning for all emollients.
  • Differin 0.1% gel SmPCAdapalene application, pregnancy contraindication and irritation cautions for off-label use.

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 for scarring or diagnostic uncertainty
Why
Investigate a progressive inflammatory follicular disorder when hair loss, atrophy or atypical plaques occur.
Interpretation and limitations
Biopsy is not routine; consent for scar and pigment risk, choose an active representative lesion and provide clinical images and differential where permitted.
2
Apply once daily initially, avoiding broken skin, then increase only to the product schedule if tolerated; stop during burning, marked redness or dermatitis.
  • 3Assess texture and pigment after six to eight weeks, continue only worthwhile treatment and explain that benefit fades when the product stops.
    • 03Atypical or complicated lesionsReopen the diagnosisPain, pus, scarring, alopecia, rapid spread, systemic symptoms or severe dietary restriction departs from ordinary keratosis pilaris.+
    1. 1Repeat full skin, hair, nail, mucosal and systemic assessment, documenting lesion evolution and nutrition, medicine and immune history.
    2. 2AlternativeSelect microbiology, nutritional blood tests or biopsy according to the specific alternative rather than ordering a broad undirected panel.
    3. 3Treat infection, eczema or deficiency through its own pathway and refer progressive scarring, hair loss or unresolved diagnostic uncertainty to dermatology.
    Key medicines and prescribing safety2 treatments · regimens, roles and cautions+
    A moisturising keratolytic option that can temporarily soften follicular plugs and improve dry surface texture.

    Urea 10% cream

    Apply a thin layer once or twice daily to rough affected body skin according to the selected product, beginning once daily on a small area.

    Can sting inflamed, fissured or freshly shaved skin; avoid eyes and mucosa, stop for dermatitis and use age-, pregnancy- and product-specific instructions.

    An off-label specialist or second-line option for selected persistent follicular plugging after lower-irritancy measures have failed.

    Adapalene 0.1% gel

    Apply a very thin film once daily in the evening to a limited affected area only when an experienced prescriber agrees an off-label trial, introducing it less often if sensitive.

    Contraindicated in pregnancy and pregnancy planning; avoid eczema, broken skin and excessive ultraviolet exposure, moisturise and stop if irritancy outweighs a cosmetic benefit.