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Keratosis Pilaris

Also known as: KP, chicken skin, keratosis pilaris

A common, benign disorder of the hair follicle presenting as rough keratotic papules, often with perifollicular erythema, on the outer upper arms, thighs, buttocks and cheeks. Harmless and usually asymptomatic; its significance is cosmetic and psychosocial rather than medical.

Evidence status

Limited

Treatment evidence consists of five small randomised trials (17–50 completers), three systematic reviews and no head-to-head laser-versus-topical study; the entire light and laser literature to January 2017 covered 17 studies and 175 patients. No trial demonstrates clearance, follow-up extends only a few months, and no validated KP-specific score allows reliable comparison. Mechanism is also unsettled: two small unreplicated studies found coiled hairs in affected follicles and absent sebaceous glands, challenging the traditional keratin-plug model.

What keratosis pilaris is, and the variants in scope#

Keratosis pilaris is a chronic disorder of the pilosebaceous unit. It presents as small, rough, follicle-centred papules, sometimes surrounded by erythema. The outer upper arms are the classic site; thighs, buttocks and cheeks are also common. In a questionnaire study of 49 evaluable UK patients, the arms were involved in 92%, legs in 59%, face in 41% and buttocks in 30%. Half reported onset in the first decade of life.[1]

Common keratosis pilaris and keratosis pilaris rubra faciei sit within this entry. The facial red variant produces conspicuous cheek erythema with follicular prominence, often beginning in childhood; a 27-patient case series reported a mean onset age of five years and minimal or no improvement with the treatments used.[5]

Scarring or atrophic disorders carrying the keratosis-pilaris name are not interchangeable with common keratosis pilaris. Keratosis pilaris atrophicans faciei, atrophoderma vermiculatum and syndromic follicular disorders require medical diagnosis.

The often-quoted prevalence of 50–70% in teenagers and about 40% in adults appears in British Association of Dermatologists patient information. A primary population-based study supporting those percentages was not located.[16]

Keratosis pilaris clusters with the dry, filaggrin-deficient barrier phenotype: 37% of the UK cohort reported a personal history of atopy and a further 16% associated dry skin, while 9 of 25 patients in the Mumbai dermoscopy series had concomitant ichthyosis vulgaris.[1, 2]

Use of keratosis pilaris care in aesthetic practice#

A practitioner may recognise a presentation consistent with previously diagnosed, uncomplicated keratosis pilaris; discuss cosmetic expectations; support gentle barrier care; and use a lawful cosmetic or an in-scope device within competence. That is different from diagnosing an unfamiliar follicular eruption or treating a medical variant.

The practical objective is improvement in roughness and, where evidence supports the chosen modality, erythema. Clearance should not be promised. Seasonal variation also complicates photographic comparison: 80% of the UK natural-history cohort reported variation, with roughly half improving in summer and roughly half worsening in winter. Baseline and review images therefore need comparable lighting, site and season where feasible.[1]

Prescription retinoids are medicines rather than routine retail cosmetics. Lasers and other devices must be used within training, device instructions, insurance and the law applying in the relevant UK nation. England’s green/amber/red licensing tiers remain proposals rather than a scheme in force.[17]

Contraindications and cautions#

Pustular, painful, rapidly changing, unilateral, ulcerated or scarring morphology, or associated systemic symptoms, should not be assumed to represent keratosis pilaris. Those features widen the differential beyond a benign cosmetic condition.

Active dermatitis, broken skin, infection, recent significant irritation or an unexplained reaction at the intended site should pause an elective keratolytic, peel or device procedure until the cause and barrier status are clear. The contraindications of the specific product or device still govern; “treating KP” does not override them.

Pigmentary risk deserves explicit consideration before an energy-based procedure. In the 810-nm diode trial, two of 23 enrolled patients withdrew because of inflammatory hyperpigmentation despite enrolment being limited to Fitzpatrick I–III. In the 755-nm alexandrite trial, three of 21 completers developed reversible post-inflammatory hyperpigmentation; two had Fitzpatrick IV and one Fitzpatrick III. No randomised study located enrolled Fitzpatrick V or VI.[11][7, 10, 11]i

The facial red variant may resemble acne or rosacea, but early-childhood onset and follicular prominence can point elsewhere.[5] Pustules and episodic tenderness should not be relabelled “inflamed KP” without considering folliculitis and other diagnoses.

Clinical uses and the evidence behind them#

Topical keratolytics. The most informative comparative trial enrolled 50 Thai participants and treated opposite upper arms with 10% lactic-acid cream and 5% salicylic-acid cream. Mean lesion reduction at 12 weeks was 66% and 52%, respectively, with a statistically significant 14-point difference favouring lactic acid. Both formulations increased conductance, but neither changed TEWL significantly. There was no vehicle-only or untreated site, so improvement cannot be attributed wholly to either acid rather than the common cream base or natural fluctuation. Funding was not disclosed; the authors declared no conflict.[9]

Systematic reviews identify lactic, glycolic and salicylic acids among the supported topical options, but the literature is heterogeneous and does not establish a standard sequence.[6, 7] Urea and topical retinoids are widely mentioned in patient information, yet no controlled vehicle comparison of either as monotherapy was located for common keratosis pilaris.

Lasers. Evidence consists of small, short studies on limited body sites. A US academic upper-arm trial of an 810-nm diode laser in 18 Fitzpatrick I–III completers improved median roughness by one point on a 0–3 scale but did not significantly improve redness.[11] A Beijing split-body trial of a 755-nm alexandrite laser in 21 Chinese completers with bilateral arm disease improved investigator-rated roughness and redness at four weeks after the final treatment, with three pigmentary reactions. It was publicly funded, and the authors declared no conflicts. Two Thai upper-arm trials reported improvements with 1064-nm Nd:YAG devices, but each had 23 or fewer completers and only four weeks' follow-up after the final treatment.[12, 13][10]

The device literature should not be presented as a large evidence base. A systematic review with a January 2017 search found just 17 light or laser studies and 175 treated patients, including variants as well as common keratosis pilaris. Reviews also disagree over whether the strongest device signal belongs to Q-switched or long-pulsed Nd:YAG technology. Funding and conflict statements for the 2022 review could not be retrieved, so its independence cannot be assumed.[6, 7, 8]

Selecting an approach#

First establish the client’s primary concern: roughness, erythema, pigment or uncertainty about the diagnosis. Evidence for one outcome does not transfer automatically to another. The diode trial, for example, improved texture but not redness.[11]

Topical selection depends on the actual formulation, intended site, cosmetic or medicinal status, concurrent irritants and manufacturer directions. Trial findings from one concentration and vehicle do not establish an ingredient-wide protocol. Keratolysis may improve feel and lesion count, while an emollient base may contribute independently.

For devices, match the exact technology and indication to the evidence rather than using “laser” as one category. The alexandrite, diode, Q-switched Nd:YAG and long-pulsed Nd:YAG studies used different mechanisms, settings, populations and outcomes.[6, 7, 8, 9, 10, 11, 12, 13] Device selection remains bounded by competence, local governance, insurance and the manufacturer’s instructions.

Expectation setting is part of selection. The appropriate promise is partial cosmetic improvement with uncertain durability, not removal of a disease or permanent clearance.

Adverse effects and their management#

Topical acids can sting, irritate and provoke dermatitis, particularly when layered with other exfoliants or used on an already impaired barrier. In the lactic-versus-salicylic study, reported irritation was mild and slightly more frequent with lactic acid, but the difference was not significant.[9] Persistent inflammation warrants stopping the suspected product and reassessing rather than adding further actives.

Energy-based procedures can cause pain, erythema, swelling, burns, dyspigmentation and scarring. Inflammatory or post-inflammatory hyperpigmentation was the consequential event in two randomised KP studies.[10, 11] Management follows the device complication pathway and scope of practice; blistering, erosion, infection, persistent pigment change or scarring needs timely medical assessment.

Physical scrubbing may worsen redness and barrier disruption. No controlled evidence was located for dry brushing, exfoliating mitts or physical scrubs as standalone KP treatments.

Referral and scope boundaries#

Medical assessment is appropriate when:

  • the diagnosis is uncertain or the eruption is pustular, painful, rapidly evolving or asymmetric;
  • there is atrophy, scarring, eyebrow loss, alopecia or progressive facial change;
  • lesions ulcerate, bleed without explanation or fail to fit a follicular benign pattern;
  • significant dermatitis, infection or a persistent adverse reaction is present;
  • a prescription medicine is being considered or existing medical treatment needs review;
  • the condition is causing substantial psychosocial distress beyond the practitioner’s remit.

Common keratosis pilaris is harmless and not infectious.[16] That reassurance does not justify diagnosing every rough follicular eruption cosmetically. Facial redness with papules may require distinction from rosacea, acne, folliculitis, eczema and a keratosis-pilaris atrophicans disorder.

Obesity and type 1 diabetes have cross-sectional associations with KP, but neither makes KP a diagnostic sign. One Brazilian comparison found KP more frequently in adults with obesity, without a relationship to obesity severity. A Serbian study found KP in 12% of young people with type 1 diabetes versus 1.5% of controls. Neither design establishes causation or warrants medical screening on the basis of KP alone.[14, 15]

Mechanism of action#

The traditional account describes excess keratin obstructing the follicular opening. Histology does show follicular plugging, but two small human studies challenge plugging as the initiating event.

A dermoscopy case series found coiled hair shafts in all 25 affected follicles examined and proposed that a circular shaft disrupts the follicular epithelium, with inflammation and abnormal keratinisation downstream. There was no unaffected control group, so specificity is unknown.[2]

A separate controlled tissue study compared 20 patients with 20 matched controls. Lesional skin showed follicular hyperkeratosis, mild T-helper-1-dominant inflammation, abnormal hair shafts, impaired barrier organisation and a striking absence of sebaceous glands. Filaggrin mutations occurred in 35%, so they explained only a minority of cases; the observed abnormalities were independent of genotype. The authors proposed sebaceous-gland absence as an early event.[3][3]

A Finnish tertiary-care atopic-dermatitis cohort associated keratosis pilaris with the FLG loss-of-function variant 2282del4 and palmar hyperlinearity, but not with eczema severity, asthma or atopic sensitisation. KP status was recorded for 347 of 502 participants, limiting generalisation.[4]

These hypotheses have not been tested against each other or independently replicated. “A keratin plug causes KP” is therefore a simplified description of what is seen, not a settled explanation of why it begins.

Commonly misstated claims#

“Keratosis pilaris is just trapped keratin”

Plugging is visible, but small human studies implicate coiled hair shafts, absent sebaceous glands and barrier abnormalities as possible upstream features. Supported statement: Keratosis pilaris involves follicular plugging, but its initiating mechanism remains uncertain.[2, 3]

“Everyone grows out of it”

Only 35% of respondents in the dedicated UK natural-history survey reported improvement with age; 43% were unchanged and 22% worsened.[1] Supported statement: Some people improve with age, but persistence or worsening is common.

“Laser treats the bumps and redness together”

The randomised diode study improved roughness but not erythema.[11] Supported statement: Outcome depends on the exact device; evidence for texture does not automatically support an erythema claim.

“Retinoids are proven for KP”

A controlled trial of a topical retinoid against vehicle for common keratosis pilaris was not located. Supported statement: Retinoids are conventionally recommended, but controlled KP-specific evidence was not found.[16]i

“Avoiding gluten or dairy treats KP”

Controlled evidence for dietary exclusion or vitamin supplementation was not located. Supported statement: No KP-specific dietary treatment can currently be presented as evidence-based.[no source found]

Areas of remaining uncertainty#

  • The initiating lesion remains unresolved: coiled hairs and absent sebaceous glands may be causes, consequences or parallel features of an upstream defect; explain mechanism as a hypothesis rather than using it to justify a particular treatment.[2, 3]
  • Durability is unknown because trials assess outcomes during treatment or within weeks of the final session; do not promise permanence or invent a maintenance interval.[8, 9, 10, 11, 12, 13]
  • No validated KP-specific severity score was located, so effect sizes cannot be compared cleanly across studies; document the client’s stated outcome and use consistent photography rather than presenting unlike trial scores as interchangeable.
  • Randomised device studies did not enrol Fitzpatrick V or VI, while pigmentary adverse events occurred in lighter studied types; disclose the evidence gap and do not imply established safety in unstudied phototypes.[10, 11]
  • Reliable population prevalence, head-to-head laser-versus-topical evidence, controlled monotherapy evidence for urea and topical retinoids, and quality-of-life data were not located; avoid ranking these options or quoting prevalence as settled without identifying the source and limitation.

Frequently asked questions#

Is keratosis pilaris an infection?

No. Common keratosis pilaris is a benign follicular disorder and is not infectious.[16] Pustules, pain or rapid change should prompt reconsideration of the diagnosis.

Can it be cured?

No reliable clearance or cure has been demonstrated. Partial improvement in texture or redness is possible, but persistence and recurrence are common and durability is poorly studied.[6, 7, 8, 16]

Does lactic acid work better than salicylic acid?

One small split-side trial favoured 10% lactic acid over 5% salicylic acid for mean lesion reduction at 12 weeks. It did not include a vehicle-only or untreated site, and the result belongs to those formulations and conditions rather than the ingredient classes as a whole.[9]

Is laser treatment proven?

Several small randomised studies report short-term improvement, but the devices, outcomes and populations differ, samples are small and long-term follow-up is absent.[8, 10, 11, 12, 13]

Is facial keratosis pilaris rosacea?

Not necessarily. Keratosis pilaris rubra faciei can create marked cheek redness with follicular prominence and often begins in childhood.[5] Uncertain facial eruptions should be medically assessed rather than treated from a label alone.

References#

Each source is graded by evidence tier. Tier 4 material (manufacturer documents, expert consensus, practitioner experience) is useful for protocol and context, and is never presented as equivalent to independent clinical evidence.

  1. Poskitt L, Wilkinson JD. Natural history of keratosis pilaris. British Journal of Dermatology. 1994 Jun;130(6):711-13.Tier 3Supports: Postal questionnaire survey of 83 patients in south Buckinghamshire, UK, diagnosed with KP in the preceding 20 years; 50 returned, 49 evaluable (59% response). Age range 18 months to 25 years, 61% female. Age of onset: first decade 51%, second decade 35%, third decade 12%, fourth decade 2%. Sites: arms 92%, legs 59%, face 41%, buttocks 30%, eyebrows 8%. Family history of KP in 39%. Personal history of atopy in 37%, associated dry skin 16%, neither 47%. Seasonal variation reported by 80%; of those, 49% improved in summer and 47% worsened in winter. Critically: 'Overall, KP had improved with age in 35% of patients, remained unchanged in 43%, and worsened in 22%. The mean age of improvement was 16 years.' SCOPE LIMITS: self-reported questionnaire, no examination, 41% non-response (likely biased toward those still symptomatic or, conversely, those still engaged with dermatology), secondary-care-diagnosed patients only so not population-representative, upper age limit 25 years so it cannot speak to KP beyond the mid-twenties. This is the only dedicated natural-history study located and it is over 30 years old.
  2. Thomas M, Khopkar US. Keratosis pilaris revisited: is it more than just a follicular keratosis? International Journal of Trichology. 2012 Oct;4(4):255-8.Tier 3Supports: Prospective dermoscopic case series, Seth GS Medical College / KEM Hospital, Mumbai, September-December 2011. 25 patients with a clinical diagnosis of KP, ages 6-38. Findings: 'All the 25 patients were found to have coiled hair shafts within the affected follicular infundibula. The hair shafts were extracted with the help of a sterile needle and were found to retain their coiled nature.' Perifollicular erythema in 11, perifollicular scaling in 9. 16 had a history of atopy, 9 had concomitant ichthyosis vulgaris. Authors' conclusion verbatim: 'we infer that KP may not be a disorder of keratinization, but caused by the circular hair shaft which ruptures the follicular epithelium leading to inflammation and abnormal follicular keratinization.' SCOPE LIMITS: 25 patients, single centre, single ethnic population, NO control group, no blinding, no quantification of how often coiled shafts occur in unaffected follicles or in normal skin. The absence of a control arm is the central weakness: without it, 'present in 100% of KP follicles' cannot establish specificity. The inference is explicitly framed by the authors as an inference, not a demonstration.Funding / interest: Conflict of interest statement: 'Conflict of Interest: None declared.' No funding source stated.
  3. Gruber R, Sugarman JL, Crumrine D, Hupe M, Mauro TM, Mauldin EA, Thyssen JP, Brandner JM, Hennies HC, Schmuth M, Elias PM. Sebaceous gland, hair shaft, and epidermal barrier abnormalities in keratosis pilaris with and without filaggrin deficiency. American Journal of Pathology. 2015 Apr;185(4):1012-21.Tier 3Supports: Controlled human tissue and functional study: 20 KP patients and 20 matched controls, assessed for filaggrin and claudin-1 genotype, dermatoscopic phenotype, and morphology by light and transmission electron microscopy. Key findings: 35% of KP patients displayed filaggrin mutations, 'demonstrating that filaggrin mutations only partially account for the KP phenotype.' Major histologic and dermatoscopic findings were 'hyperkeratosis, hypergranulosis, mild T helper cell type 1-dominant lymphocytic inflammation, plugging of follicular orifices, striking absence of sebaceous glands, and hair shaft abnormalities in KP lesions but not in unaffected skin sites.' Barrier function and paracellular permeability were abnormal in both interfollicular and follicular stratum corneum of lesional skin, correlating with impaired extracellular lamellar bilayer maturation. All features were independent of filaggrin genotype. Corneodesmosome and tight junction ultrastructure was normal; claudin-1 protein and gene analysis unremarkable. Authors' conclusion: 'our findings suggest that absence of sebaceous glands is an early step in KP pathogenesis, resulting in downstream hair shaft and epithelial barrier abnormalities.' SCOPE LIMITS: 20 cases. Ex-vivo tissue analysis. The causal ordering (sebaceous loss first, then hair shaft and barrier change) is proposed on cross-sectional tissue, not demonstrated longitudinally. Note this study locates the primary lesion in the sebaceous gland, whereas source 2 locates it in the hair shaft: the two 'corrections' to the classic model are not the same correction.
  4. Salava A, Salo V, Remitz A. Keratosis pilaris and filaggrin loss-of-function mutations in patients with atopic dermatitis - results of a Finnish cross-sectional study. Journal of Dermatology. 2022 Sep;49(9):928-32.Tier 3Supports: Cross-sectional observational study of 502 randomly selected atopic dermatitis patients at a Finnish tertiary centre, single clinical examination, with Rajka-Langeland score, EASI, total IgE and common filaggrin loss-of-function genotyping. KP was significantly associated with palmar hyperlinearity (OR 4.664, 95% CI 2.072-10.496, p<0.001) and with the FLG loss-of-function mutation 2282del4 (OR 4.917, 95% CI 1.961-12.330, p<0.001). Crucially, there was NO link between KP and atopic dermatitis severity (p=0.649), asthma (p=0.230) or atopic sensitisation (p=0.351). DENOMINATOR, CHECKED IN THE FULL TEXT: the results section reports '28 KP vs. 319 with no KP' and the results table gives 28 (8.1%) versus 319 (91.9%), so KP status was classified in 347 of the 502, not in all 502. The within-study KP frequency is therefore 8.1%, not 5.6%. The authors state 'the prevalence of KP in the cohort was generally low and KP seems to be infrequent in Finnish AD patients', attributing this to the rarity of the tested FLG mutations in Finns. SCOPE LIMITS: single-country, tertiary-care AD population only, so it cannot give general-population prevalence; only common FLG variants tested; cross-sectional; the authors themselves list the low KP count and reliance on retrospective patient-derived information as limitations. Its most useful contribution is negative: KP does not mark more severe atopic disease.Funding / interest: 'The authors state no conflicts of interest.' No commercial funding disclosed.
  5. Marqueling AL, Gilliam AE, Prendiville J, Zvulunov A, Antaya RJ, Sugarman J, Pang ML, Lee P, Eichenfield L, Metz B, Goldberg GN, Phillips RJ, Frieden IJ. Keratosis pilaris rubra: a common but underrecognized condition. Archives of Dermatology. 2006 Dec;142(12):1611-16.Tier 3Supports: Multinational retrospective case series (dermatology practices in the USA, Canada, Israel and Australia) describing 27 patients with keratosis pilaris rubra. Marked erythema with follicular prominence in all patients, most commonly on the lateral cheeks and proximal arms and legs, with both more marked erythema and more widespread involvement than in common KP. Mean age at onset 5 years (range birth to 12 years). 63% male. No patient had atrophy or scarring. On treatment, verbatim: 'Various treatments were used, with minimal or no improvement in most cases.' Authors conclude it is 'a relatively common but uncommonly reported condition' and a variant of KP without the atrophy or hyperpigmentation of certain other KP variants. SCOPE LIMITS: 27 patients, retrospective, convenience sample from specialist paediatric dermatology practices, no denominator so 'common' is an impression not a rate, no standardised treatment protocol or outcome measure. Its value is descriptive: it establishes the facial red variant as a real, non-scarring entity distinct from keratosis pilaris atrophicans.
  6. Beyron A. Keratosis pilaris: a systematic review of the literature and strategies for optimal treatment. European Journal of Dermatology. 2025 Oct 1;35(5):387-93.Tier 1Supports: Most recent systematic review located. 27 articles published 2011-2024, comprising topical or laser monotherapies, comparative analyses and combination treatments. Findings: lactic and glycolic acids were the preferred topicals and demonstrated efficacy; the Nd:YAG laser 'yielded consistently favourable outcomes'; among ablative lasers CO2 showed efficacy and erbium:YAG appeared promising with fewer adverse effects. States plainly that 'despite the range of available topical and laser therapies, no standardized approach exists for selecting one treatment over another', and concludes that management is 'a multimodal strategy centred on patient education, topical treatments and laser therapies', proposing a stepwise stratified approach. SCOPE LIMITS: single-author review; no formal meta-analysis or pooled effect estimate; no GRADE or risk-of-bias rating reported in the abstract; the proposed stepwise algorithm is the author's synthesis, not a trial-derived protocol. Note that 'patient education' is placed first in the recommended strategy.
  7. Maghfour J, Ly S, Haidari W, Taylor SL, Feldman SR. Treatment of keratosis pilaris and its variants: a systematic review. Journal of Dermatological Treatment. 2022 May;33(3):1231-42.Tier 1Supports: Systematic search of PubMed/MEDLINE, Embase and Web of Science identifying 1150 non-duplicated articles, of which 47 were included. Primary outcomes were treatment type and degree of improvement. Conclusion: 'the most supported form of treatment for KP is laser therapy, particularly the QS:Nd YAG laser'; topical treatments including mineral oil-hydrophilic petrolatum, tacrolimus, azelaic acid and salicylic acid 'are also effective at least for improving the appearance of KP'. Authors state 'the measured treatment outcomes varied among studies'. SCOPE LIMITS: no meta-analysis, no pooled effect size, heterogeneous and largely uncontrolled included studies, outcome measures not comparable across studies. Note this review favours Q-switched Nd:YAG while sources 6 and 8 emphasise the long-pulsed 1064 nm device: they are different lasers with different mechanisms, and the reviews do not agree on which.Funding / interest: ACCESS FAILURE, RECORDED HONESTLY: neither the PubMed record nor the Europe PMC core record carries a conflict-of-interest statement or any grant record for this article, and the publisher's full text (Taylor & Francis) returns HTTP 403, so the declaration of interest and funding statement could not be read. This is stated as unverified rather than assumed either way. The review's five authors are affiliated to the Center for Dermatology Research, Wake Forest School of Medicine. The absence of a retrievable statement should NOT be read as an absence of interests: the senior author, Steven R Feldman, routinely declares extensive consulting, speaking and research relationships with dermatological and pharmaceutical manufacturers in his other publications, so the disclosure position for this review is unknown rather than clean. Consult the published disclosure section directly before relying on it.
  8. Kechichian E, Jabbour S, El Hachem L, Tomb R, Helou J. Light and laser treatments for keratosis pilaris: a systematic review. Dermatologic Surgery. 2020 Nov;46(11):1397-1402.Tier 1Supports: Systematic review of MEDLINE, Embase and Cochrane, search date 15 January 2017, of all studies using light and laser devices for KP and its variants. THE HEADLINE NUMBER FOR HONEST EXPECTATION SETTING: 'Seventeen studies related to light and laser treatments were retained for analysis. The total number of treated patients was 175. Of which, 22 patients had KP atrophicans faciei, 17 patients had KP rubra, and 136 patients had KP.' Authors describe topical treatments as often yielding 'ineffective and temporary results' and conclude that light and laser devices are 'emerging as promising therapeutic options for a disfiguring disease that still lacks, until today, an effective long-term treatment.' SCOPE LIMITS: search closed January 2017, so it predates the alexandrite trial (source 10) and the sham-controlled Nd:YAG trial (source 11); no pooled analysis; 175 patients across 17 studies is roughly 10 patients per study, most uncontrolled.
  9. Kootiratrakarn T, Kampirapap K, Chunhasewee C. Epidermal permeability barrier in the treatment of keratosis pilaris. Dermatology Research and Practice. 2015;2015:205012.Tier 2Supports: Randomised, assessor-blinded comparative trial at the Institute of Dermatology, Bangkok, in 50 enrolled participants; both creams applied twice daily for 3 months, assessed at baseline, 4, 8 and 12 weeks and 4 weeks after treatment, with high-frequency conductance and transepidermal water loss measurement. DESIGN CORRECTION, FROM THE FULL TEXT: this is NOT a parallel two-arm trial. The introduction calls it 'a prospective split side-controlled trial' and the methods state patients were 'told to apply the one designated agents twice daily on each of their extensor upper arms by using one hand to apply one test medication to the opposite upper arm and vice versa' — i.e. each participant received lactic acid on one arm and salicylic acid on the other, acting as their own control. The abstract's phrasing ('randomized for treatment with either 10% LA or 5% SA creams') implies parallel groups and contradicts the methods; the paper is internally inconsistent on this point and it is recorded here unresolved. Blinding is supported: 'the examining dermatologists were blinded to this information'. Result: mean reduction in lesions from baseline was 66% for 10% lactic acid and 52% for 5% salicylic acid; the 14 percentage-point difference is reported as statistically significant (P<0.05) favouring lactic acid, and both agents showed significant within-patient reduction at 4, 8 and 12 weeks. Conductance (hydration) rose with both and was maintained through follow-up. No significant change in TEWL. Adverse effects were limited to mild irritation, slightly more frequent with lactic acid but not significantly so. The vehicle was matched between the two actives (a defined base cream), but there was NO vehicle-only or untreated site, so the base-cream and natural-history contribution to the 66% and 52% cannot be separated out. SCOPE LIMITS: 50 patients, single centre, Thai population, only 4 weeks of post-treatment follow-up, lesion counts by questionnaire. Reduction of lesions is not clearance.Funding / interest: 'The authors declare that there is no conflict of interests regarding the publication of this paper.' No funding source disclosed.
  10. Li M, Bai Y, Duan Z, Yuan R, Liu X, Liu Y, Liang X, Wu H, Zhuo F. Efficacy and safety of long-pulsed 755-nm alexandrite laser for keratosis pilaris: a split-body randomized clinical trial. Dermatology and Therapy (Heidelberg). 2022 Aug;12(8):1897-1906. Trial registration ChiCTR2100054489.Tier 2Supports: Prospective, rater-blinded, split-body randomised trial, Beijing Friendship Hospital. 22 patients with bilateral arm KP enrolled, 21 completed (15 women, 6 men). One arm randomised to long-pulsed 755 nm alexandrite (GentleMax Pro, Candela; 14-16 J/cm2, 15 mm spot, 3 ms pulse, 1 Hz, two non-overlapping passes) in four sessions three weeks apart; a uniform moisturising lotion was applied to BOTH arms daily, so the comparator is moisturiser rather than nothing. At 4 weeks after the fourth treatment, laser side vs control side median scores: total 2.0 vs 4.5, roughness 1.0 vs 2.0, redness 1.0 vs 2.0, all P<0.05 by physician assessment; patient self-assessment total 2.0 vs 4.0, roughness 1.0 vs 2.0, redness 1.0 vs 2.0, all P<0.05. Excellent improvement rates, laser vs control: follicular plugs 57.1% vs 14.3%, perifollicular erythema 52.4% vs 9.5%, perifollicular hyperpigmentation 47.6% vs 14.3%, epidermal bulges 57.1% vs 19.1% (all P<0.05). Histopathology showed improved follicular plugging and inflammatory infiltrate. ADVERSE EVENTS: 'Three patients exhibited reversible postinflammatory hyperpigmentation.' The discussion identifies those three by phototype: '3 out of the 21 patients developed reversible hyperpigmentation, and the phototypes of these patients were 2 patients with type IV and 1 patient with type III', from which the authors speculate the cause was excessive laser energy in darker skin and advise caution on energy selection. Cohort Fitzpatrick types: II 19.1%, III 61.9%, IV 19.1%. Note that 'reversible' is the authors' word; the reported resolution at one month post-treatment was partial (around 30% improvement), so it evidences a fading, not a documented full clearance. SCOPE LIMITS: 21 completers, single centre, Chinese population, no Fitzpatrick V-VI participants, follow-up only 4 weeks after the final session so durability is unknown, subjective ordinal scoring, arms only.Funding / interest: 'This research was supported by the Beijing Natural Science Foundation (No. 7222040) and Beijing Friendship Hospital, Capital Medical University (Contract grant number: Seed Project YYZZ202128). The authors funded the Rapid Service Fee.' Disclosures: all nine named authors 'have nothing to disclose'. No manufacturer funding identified despite a named commercial device (Candela GentleMax Pro).
  11. Ibrahim O, Khan M, Bolotin D, Dubina M, Nodzenski M, Disphanurat W, Kakar R, Yoo S, Whiting D, West DP, Poon E, Veledar E, Alam M. Treatment of keratosis pilaris with 810-nm diode laser: a randomized clinical trial. JAMA Dermatology. 2015 Feb;151(2):187-91. ClinicalTrials.gov NCT01281644.Tier 2Supports: Split-body, rater-blinded, parallel-group, balanced (1:1), placebo-controlled randomised trial at an urban US academic dermatology practice, March-October 2011. 26 screened, 23 enrolled, 18 completed; 3 lost to follow-up and 2 withdrew 'owing to inflammatory hyperpigmentation after the laser treatment'. Fitzpatrick skin types I-III only. Three treatments 4-5 weeks apart with the 810 nm pulsed diode laser to one randomised arm. Two blinded dermatologists rated at 12 weeks on 0-3 scales. RESULTS: median roughness/bumpiness 1.0 (IQR 1-2) treated vs 2.0 (IQR 1-2) control, difference of 1, P=0.004; median combined overall score 3.0 (IQR 2-4) vs 4.0 (IQR 3-5), difference of 1, P=0.005. CRITICALLY, redness did NOT improve: 'the median redness score reported by the 2 blinded raters for the treatment and control sides was 2.0 (interquartile range [IQR], 1-2; P = .11)'. Authors conclude 'baseline erythema is not improved' and that complete treatment of both erythema and texture 'may require diode laser treatment combined with other laser or medical modalities that address redness.' SCOPE LIMITS: 18 completers, Fitzpatrick I-III only, one 12-week endpoint, 0-3 ordinal scale with a median improvement of a single point, arms only, and a 22% dropout including two adverse-event withdrawals in light skin types.
  12. Maitriwong P, Tangkijngamvong N, Asawanonda P. Innovative 1064-nm Nd:YAG laser significantly improves keratosis pilaris: a randomized, double-blind, sham-irradiation-controlled trial. Lasers in Surgery and Medicine. 2020 Jul;52(6):509-14.Tier 2Supports: Randomised, sham-irradiation-controlled trial at Chulalongkorn University, Bangkok. 23 subjects with untreated KP on the upper outer arms; one arm divided into upper and lower parts, one part randomised to 1064 nm Nd:YAG and the other to sham irradiation, four treatments at 4-week intervals. All 23 completed. Objective Antera 3D measurement showed statistically significant reduction of skin roughness versus control (P<0.001). Subject Global Improvement Score showed significant improvement in roughness, erythema, hyperpigmentation and overall appearance (P<0.001 for all), and satisfaction scores were significantly better on the treated part (P<0.001). 'No adverse events including burning, bulla, erosion, post-inflammatory hyper/hypopigmentation, and scar formation developed in any subjects.' SCOPE LIMITS: 23 Thai subjects, single centre, within-arm design over a small skin area, described in the title as double-blind but in the methods as single-blind randomisation, the erythema and pigment improvements rest on SUBJECT self-report rather than the objective device measure (Antera3D was used to measure roughness, erythema and hyperpigmentation, but only the roughness result is reported, so the erythema and pigment device findings are unstated rather than known to be null), and assessment was at 4 weeks after the last session with no longer-term follow-up. Absolute effect sizes are not reported in the abstract.
  13. Saelim P, Pongprutthipan M, Pootongkam S, Jariyasethavong V, Asawanonda P. Long-pulsed 1064-nm Nd:YAG laser significantly improves keratosis pilaris: a randomized, evaluator-blind study. Journal of Dermatological Treatment. 2013 Aug;24(4):318-22.Tier 3Supports: Randomised, evaluator-blind, split-body study, Chulalongkorn University, Bangkok. 18 patients with untreated KP on the upper outer arms enrolled, 17 completed. One arm treated with long-pulsed 1064 nm Nd:YAG at 30 ms pulse width and 34 J/cm2 fluence; the contralateral arm served as untreated control. Three consecutive treatments at 4-week intervals. Three blinded dermatologists graded digital photographs on a quartile scale for global improvement, erythema and number of keratotic papules. Statistically significant improvements in global assessment, erythema and keratotic papule number at 4 weeks after the last treatment (p<0.05). All patients reported their lesions improved and were satisfied. SCOPE LIMITS: 17 completers, Thai patients only, untreated (not sham) control so the evaluator blinding is the only protection against expectancy effects, quartile photographic grading with no absolute effect sizes reported, assessment 4 weeks after the final session only, arms only. Tiered at 3 rather than 2 on account of size and the absence of a sham comparator. This is the trial most often cited as establishing 'Nd:YAG works for KP'.
  14. Boza JC, Trindade EN, Peruzzo J, Sachett L, Rech L, Cestari TF. Skin manifestations of obesity: a comparative study. Journal of the European Academy of Dermatology and Venereology. 2012 Oct;26(10):1220-3.Tier 3Supports: Comparative cross-sectional study, Hospital de Clinicas de Porto Alegre, Brazil. 76 obese patients (BMI 30+) and 73 normal-weight volunteers (BMI 18.5-24.9), all examined by the same examiner and investigated for metabolic syndrome. Keratosis pilaris showed a statistically significant relationship with obesity (P=0.006), alongside striae (P<0.001), plantar hyperkeratosis (P<0.001), acrochordons (P=0.007), intertrigo (P<0.001), pseudoacanthosis nigricans (P<0.001), lymphoedema (P=0.002) and bacterial infections (P=0.05). Unlike striae, pseudoacanthosis nigricans and bacterial infections, KP was NOT found to correlate with the degree of obesity. SCOPE LIMITS: 149 participants, single centre, Brazilian population, cross-sectional so no causal direction and no temporal ordering, single unblinded examiner, no adjustment reported for age or atopy, and no prevalence figures for KP in each group are given in the abstract. The absence of a dose-response relationship with obesity severity weakens any causal reading.
  15. Pavlovic MD, Milenkovic T, Dinic M, Misovic M, Dakovic D, Todorovic S, Dakovic Z, Zecevic RD, Doder R. The prevalence of cutaneous manifestations in young patients with type 1 diabetes. Diabetes Care. 2007 Aug;30(8):1964-7.Tier 3Supports: Case-control study, Military Medical Academy, Belgrade. 212 unselected type 1 diabetic patients aged 2-22 (diabetes duration 1-15 years) compared with 196 healthy sex- and age-matched controls. 'Keratosis pilaris affected 12% of our patients vs. 1.5% of control subjects.' A significant association was found between acquired ichthyosis and keratosis pilaris (OR 1.53, 95% CI 1.09-1.79, P<0.001). Overall, 68% of diabetic patients had at least one cutaneous disorder vs 26.5% of controls (P<0.01). The authors conclude that acquired ichthyosis and keratosis pilaris 'develop early in the course of the disease', in contrast to diabetic hand and rubeosis faciei which were related to disease duration. SCOPE LIMITS: type 1 diabetes only in children and young adults, single Serbian centre, cross-sectional, examiners not stated to be blinded to diabetes status, and the 1.5% control rate is far below the KP prevalence usually quoted for adolescents, which suggests a strict diagnostic threshold or ascertainment differences and means the 12% figure should not be compared with population estimates from other studies.
  16. British Association of Dermatologists. Keratosis pilaris (patient information leaflet). Produced March 2008; last updated November 2021; stated next review date November 2024.Tier 4Supports: UK professional-body patient information. States prevalence as affecting 'more than half (50-70%) of teenagers and many (approximately 40%) adults'. On cause: 'We do not fully understand the cause of keratosis pilaris, but it appears to be associated with certain genes.' On cure, answers directly: 'No. However, it often (but not always) clears up during adult life.' On treatment: 'Creams containing salicylic acid, lactic acid and/or urea can soften and flatten the bumps'; topical retinoids may be prescribed; treatments improve the condition temporarily rather than clearing it; other, more expensive options exist but are not NHS-funded. SCOPE LIMITS: this is patient information, not a clinical guideline, and it is not systematically referenced: the 50-70% and 40% prevalence figures are given without a primary citation and I could not trace them to a population study. The stated next review date of November 2024 has passed, so the leaflet is overdue for review as of August 2026. It is cited here as the authoritative UK lay-facing position and as evidence of what UK patients will have been told, not as epidemiological evidence.
  17. Department of Health and Social Care. The licensing of non-surgical cosmetic procedures in England: consultation document. GOV.UK. Consultation open to 11:59pm on 28 October 2023.Tier 1Supports: PROPOSAL ONLY, NOT IN FORCE. Sets out a proposed three-tier green/amber/red licensing model for England. GREEN tier (practitioners meeting agreed standards may perform) includes microneedling; mesotherapy; intense pulsed light (IPL) and LED therapies; chemical peels that 'involve destruction only into viable epidermis (the outermost layer of the skin)'; non-ablative laser hair removal; and photo rejuvenation, defined as 'the use of a laser to treat skin conditions including wrinkles, acne scarring, sun damage'. AMBER tier (licensed practitioners require oversight by a regulated healthcare professional) includes 'non-ablative lasers (excluding photo rejuvenation and hair removal)' and medium depth peels involving 'full thickness destruction of entire epidermis into upper dermis'. RED tier (restricted to regulated healthcare professionals at CQC-registered premises) includes 'deeper chemical peels such as phenol peels' and 'lasers which target the deeper layers of the dermis. For example, CO2 lasers, where used for extensive fully ablative resurfacing'. On age, the document proposes 'that the licensing scheme requirements or conditions will prohibit practitioners from performing any procedures included within the scheme on people under the age of 18 unless the procedure has been approved for use on a person under 18 by a GMC registered doctor and is carried out by a specified healthcare professional' — directly relevant to KP, which most often presents in teenagers. SCOPE LIMITS: England only. The document itself states 'the procedures listed below are indicative examples only and may change based on the outcome of this consultation'. This is the 2023 consultation document; tier placements come from it and from no later source. The DHSC consultation response published 7 August 2025 does not assign individual procedures to tiers and states that responses highlighted 'where further work is needed to determine specific procedures' classification within the scheme'. No licensing scheme is in force and no procedure has been formally assigned to a tier in law.