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Comedones

Also known as: comedo, blackheads, whiteheads, open comedones

Comedones are hair follicles blocked by a mixture of skin cells and sebum, the skin's oil. Open comedones are blackheads; closed comedones are whiteheads. They are common features of acne and help guide the choice of skincare and medical treatment.

In plain English — Blackheads and whiteheads are two forms of the same problem: oil and skin cells collecting in a hair follicle. With acne, treatments such as prescribed adapalene can help reduce these blocked follicles over time. The small oily filaments often seen on the nose are a normal feature of skin and are different from comedones.

Evidence status

Strong

Comedones are established clinical features of acne, with licensed topical treatments and guideline-supported care. Evidence for an individual procedure, cosmetic formula or prediction of a lesion's future course needs separate assessment.

What comedones are, and the types encountered#

A comedo is a plugged hair follicle; comedones is the plural. The plug contains accumulated skin cells and sebum. Open comedones, or blackheads, have a visible dark opening. Closed comedones, or whiteheads, form small skin-coloured or whitish bumps with a covered or very small opening. Comedonal acne is the pattern in which these lesions predominate, often on the forehead and chin.[2, 3]

Microcomedones are the microscopic stage, below unaided visibility. Macrocomedones are larger closed comedones. Comedones also occur in settings such as chronically sun-damaged skin; their distribution and surrounding skin help establish the diagnosis.[2, 3]

Sebaceous filaments and other small bumps

Sebaceous filaments are the usual contents of some oil-rich follicles. Human microscopy describes pale cylindrical material containing sebum and skin-cell fragments, particularly in the central face and nose, as a common normal variation. Recognising these structures supports an explanation of normal skin rather than automatically classifying every visible follicle as acne.[4]

Milia are small keratin-filled cysts, often pearly white around the eyelids and cheeks. Pustules have visible pus and an inflamed base. These distinctions matter because a white bump can represent several different structures; colour alone is insufficient to select a removal procedure.[2, 5, 14]

Use of comedones in aesthetic practice#

Recognising the lesion pattern helps a skincare professional explain the skin’s appearance, select compatible cosmetic support and identify when medical assessment would be useful. NICE supports non-alkaline syndet cleansing and skincare chosen to avoid oily or comedogenic preparations, within a wider discussion of the person’s acne and priorities.[1]

Prescription treatment is a separate clinical decision. For example, Differin adapalene gel is a prescription medicine with an indication for mild-to-moderate acne involving comedones, papules and pustules. A non-prescribing practitioner can support an existing plan and communicate concerns; no authorisation to change that prescription is given here.[1, 6] The full acne pathway belongs to acne vulgaris, and procedural assessment and scope belong to extraction.

Contraindications and cautions#

The cautions attach to the proposed intervention, rather than to the word comedone. Pregnancy or a planned pregnancy excludes topical retinoid treatment under NICE guidance. Product hypersensitivity is another contraindication to the relevant medicine.[1, 6]

For clients using adapalene, its prescribing information excludes application to broken, sunburnt or eczematous skin. Current irritation and the other products already being used therefore matter when considering an additional aesthetic treatment; a combined plan needs to account for skin tolerance.[1, 6]

Clinical uses and the evidence behind them#

Topical treatment of acne-associated comedones

NICE includes fixed adapalene/benzoyl-peroxide combinations among first-line acne treatments. Its maintenance options, when indicated, include that combination and selected individual topical medicines. Treatment selection also accounts for inflammatory lesions, contraindications, previous response and patient preference.[1, 6]

Galderma’s Epiduo product information reports two 12-week controlled trials involving 2,185 participants aged 12–50 with both inflamed lesions and comedones, treating the face and other affected areas. The combined-trial median reduction in non-inflammatory lesion counts was 52.8% with its adapalene/benzoyl-peroxide gel and 30.7% with vehicle. These percentages describe reduced lesion counts, not the proportion of patients whose skin cleared; the table supplies no confidence intervals. This is manufacturer-reported evidence for a particular medicine, rather than a result for cosmetic retinol or every acne serum.[7]

Removal of selected lesions

Extraction physically removes the contents of an existing comedo. Indian dermatologist-focused consensus recommends it as an adjunct in predominantly comedonal acne, while assigning its own Level D evidence grade.[9]

A 2024 Chinese split-face randomised trial in dense facial comedones reported mean count reductions of 46.36% with extraction and 64.49% with ultra-pulse CO2 laser after four treatments given two weeks apart. The comparison favoured laser, but there was no untreated side; it cannot determine either intervention’s benefit over observation. The abstract omits the participant number and age range. Public research grants are indexed, while the full conflict statement was unavailable. This finding informs a specialist discussion, not a general recommendation to laser blackheads.[8]

The separate extraction, salicylic acid and chemical peel references cover those interventions. Their evidence and risks remain specific to the procedure or formulation.

Selecting care for comedones#

The useful starting point is the whole presentation: lesion type and distribution, inflamed lesions, existing medicines, skin tolerance, previous treatment response and what troubles the client. A few visible follicles, predominantly comedonal acne and acne with scarring call for different conversations. This is clinical reasoning based on the assessment factors in NICE guidance, rather than a treatment algorithm based on a pore count.[1, 6, 10]i

Product selection concerns the finished formula and the client’s experience with it. A four-week human study tested cosmetic products under patches on the upper backs of six selected volunteers and found that ingredients classified as comedogenic did not necessarily make their finished formulations comedogenic. Funding and commercial interests could not be established from the accessible abstract. This supports caution with ingredient-score checkers; it does not establish how any individual face will respond.[10]

Adverse effects and their management#

Irritation associated with topical treatment

Dryness, burning, redness or dermatitis may arise with adapalene treatment. Its prescribing information allows treatment interruption or discontinuation when reactions warrant it and warns that peeling, drying or otherwise irritating products can add to irritation. Significant new reactions merit discussion with the prescriber or pharmacist before further active treatment is added.[1, 6, 9]

Trauma associated with manipulation

Persistent picking or scratching can increase scarring risk. Procedural consensus separately warns that undue extraction force can increase inflammation and potential scarring.[1, 6, 9] These are reasons to minimise additional trauma and assess an adverse reaction rather than repeatedly working on a resistant or increasingly inflamed lesion. Procedure-specific complications are covered in the extraction entry.

Referral and scope boundaries#

NICE recommends a dermatologist-led or agreed specialist pathway when the diagnosis is uncertain, or when nodulocystic acne or acne conglobata is present. It also identifies treatment failure, developing scars, persistent pigmentary change and persistent psychological distress as reasons to consider referral. For a skincare practitioner, these are reasons to facilitate clinical assessment rather than simply increase treatment intensity.[1]

Acne-like disease with rapid, severe deterioration and systemic illness needs urgent medical assessment. Suspected acne fulminans requires same-day referral under NICE guidance.[1]

A solitary unusual opening, an atypical cluster or a pattern outside ordinary acne also warrants diagnostic attention before attempted removal: comedones or similar openings occur in several other conditions.[1, 2]i Emotional impact remains relevant even where the visible lesion burden is modest.[1]

These are clinical referral principles. Local referral arrangements apply; neither NICE guidance nor a foreign procedural consensus is a UK-wide licence to perform extraction.[1, 6, 9]i

Mechanism of action#

The relevant unit is the hair follicle and its associated sebaceous gland. Accumulation of cells from the follicular lining, together with sebum, contributes to a plug. The size and configuration of the opening help determine whether the visible lesion is open or closed.[2, 3]

Lesions can change over time. In a study of 25 people with untreated facial acne photographed over 12 weeks, 54% of inflammatory lesions had been preceded by visible comedones and 28% by normal-appearing skin. The denominator was the inflammatory lesions being traced backwards, not all comedones being followed forwards. Fortnightly photographs could miss intermediate or microscopic changes, so the study describes pathways without assigning a personal progression risk to each blackhead.[12]

Commonly misstated claims#

Clinical classification and inflammation

Claim heard:“Non-inflammatory” means no inflammatory biology

Literature finding: The label describes the visible lesion category. Human biopsy research detected immune and blood-vessel activation in clinically uninvolved acne skin before visible lesions or increased cell proliferation. The accessible abstract does not supply participant numbers or biopsy-site details, so these findings should not be turned into a quantitative rule about an individual lesion.[11]

Supported statement: Comedones are clinically classed as non-inflammatory lesions; that classification does not exclude early immune activity in acne skin.

Sebaceous-filament refilling

Claim heard:“Sebaceous filaments refill on an exact 30-day clock”

Literature finding:The number has a primary source: a 1976 human microscopy paper reported follicular refilling within 30 days after expression. Its accessible abstract gives neither a participant denominator nor a spread of refill times. “Within 30 days” is also different from “always at 30 days”.[4]

Supported statement: Sebaceous filaments can reform after removal; the historical observation is not a validated personal maintenance schedule.

Blackhead pigmentation

Claim heard:“Blackhead colour has one settled chemical explanation”

Literature finding:Published explanations differ. DermNet attributes blackhead colour to melanin, whereas a 1983 human ultrastructural study of expressed black plugs found no melanosomes and disputed that explanation. The study’s accessible abstract does not give its sample size or establish an alternative exclusive pigment explanation.[3, 13, 14]

Supported statement: A blackhead has a pigmented follicular plug, not a deposit of dirt; a single exclusive pigment explanation goes beyond the sources compared here.[3, 13, 14]

Areas of remaining uncertainty#

  • Individual-lesion prognosis. No validated method for predicting during an ordinary skincare consultation which particular comedo will become inflamed was identified.[no source found] Management therefore rests on the overall clinical picture rather than a promised future for a single pore.
  • Durability of procedural clearance. The accessible 2024 extraction-versus-laser trial abstract reports results after its treatment series, without later recurrence data; that comparison cannot support a promise of lasting clearance.[8]

Frequently asked questions#

Which entry covers comedone removal?

Extraction covers removal, its evidence and procedural scope. The subject here is the lesions themselves and how they fit into assessment and care.

What information is useful when a client seeks medical advice?

The history of the eruption, treatments already tried, current medicines, reactions and the client’s main concern all help contextualise the consultation. Scarring, persistent colour change and psychological impact are particularly relevant to the referral discussion.[1]

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. National Institute for Health and Care Excellence. Acne vulgaris: management. NG198. Recommendations. Published 25 June 2021; live page last updated 3 August 2026.Tier 1Supports: Personally retrieved complete live HTML on 16 September 2026. Sections 1.2, 1.4, 1.5 and 1.7 support skincare, referral, first-line and maintenance choices, pregnancy restrictions, irritation and patient-centred assessment. Severity definitions include any number of comedones within mild-to-moderate acne; comedone count alone does not determine the whole presentation. This is clinical guidance, not a four-nation procedure-licensing instrument.Funding / interest: NICE institutional clinical guidance; not a manufacturer efficacy claim. Individual committee declarations were not re-audited for this entry.
  2. DermNet. Comedo. February 2017.Tier 4Supports: Clinical definition and open/closed morphology; comedones and comedone-like structures occur in acne and other conditions, including solar comedones, hidradenitis suppurativa, comedone naevus, cysts and some other lesions. Expert reference, not a diagnostic-accuracy study.Funding / interest: DermNet clinical reference. No article-specific sponsor or author conflict declaration located on the retrieved page; the site displays advertising.
  3. Oakley A, Ngan V, Morrison C. Comedonal acne. DermNet. Updated April 2014.Tier 4Supports: Comedonal acne as a predominantly comedonal pattern; forehead/chin distribution; microcomedones, macrocomedones and solar comedones; follicular cell accumulation and sebum. The older treatment and dietary suggestions are not substituted for current NICE guidance.Funding / interest: DermNet clinical reference. No article-specific sponsor or author conflict declaration located on the retrieved page; the site displays advertising.
  4. Plewig G, Wolff HH. Sebaceous filaments [article in German; English abstract]. Arch Dermatol Res. 1976;255(1):9–21. doi:10.1007/BF00581673. PMID:130839.Tier 3Supports: English MEDLINE abstract personally retrieved through Europe PMC on 16 September 2026. Human facial light/electron microscopy describes sebaceous filaments as a common morphological variant, distinct from microcomedones and trichostasis spinulosa. Abstract reports follicular refilling within 30 days but gives no sample size or distribution of refill times. Full German article not retrieved.Funding / interest: Funding and conflicts were not stated in the retrieved abstract; neither independence nor commercial involvement is established.
  5. Gupta M, Oakley A. Milium. DermNet. 2009.Tier 4Supports: Milia are small keratin-containing cysts, commonly pearly white and prominent around eyelids/cheeks; they are a differential from comedones. Used for recognition, not to transfer a milia-removal technique.Funding / interest: DermNet clinical reference. No article-specific sponsor or author conflict declaration located on the retrieved page; the site displays advertising.
  6. Galderma (UK) Limited. Differin 0.1% w/w Gel: Summary of Product Characteristics. emc. Updated 5 October 2022.Tier 1Supports: Product-specific prescription status, mild-to-moderate acne indication involving comedones/papules/pustules on face/chest/back, pregnancy and planning-pregnancy contraindications, damaged-skin warnings, additive irritation and response to severe irritation. The proposed pharmacological mechanism is distinguished from human efficacy; its rhino-mouse comedolysis is not presented as a human experiment.Funding / interest: Manufacturer/marketing-authorisation-holder product information supplied by Galderma (UK) Limited. This is regulated prescribing information, not an independent clinical trial.
  7. Galderma (UK) Limited. Epiduo 0.1%/2.5% Gel: Summary of Product Characteristics. Text revised 17 October 2024; emc updated 18 November 2024.Tier 1Supports: Section 5.1 reports two 12-week controlled trials in 2,185 participants aged 12–50 with inflammatory and non-inflammatory acne lesions, treating the face and other affected sites as needed. Combined-trial median non-inflammatory lesion-count reduction: 52.8% combination versus 30.7% vehicle. These are lesion-count reductions, not proportions of people cleared; no confidence intervals accompany that table. Product-specific data, not class-wide cosmetic evidence.Funding / interest: Galderma (UK) Limited is the marketing-authorisation holder and source of this manufacturer-reported clinical-trial summary. The SmPC does not supply the individual trial funding/COI declarations.
  8. Yang MY, Qiao SM, Ning DC, Ding YH, Zeng WH, Wang Z. Treatment effect of ultra-pulse dynamic CO2 laser and comedone extractor in dense comedones: a prospective, randomized, split-face, evaluator-blind, controlled clinical trial. Lasers Med Sci. 2024;39(1):233. doi:10.1007/s10103-024-04104-0. PMID:39235691.Tier 2Supports: MEDLINE abstract personally retrieved through Europe PMC. Single-centre Chinese split-face trial: mean comedone-count reduction after four treatments at two-week intervals was 46.36% extraction versus 64.49% laser, P<0.001. No untreated side. Abstract omits participant number, age range, phototype and later recurrence data; these are not inferred from responder percentages.Funding / interest: Europe PMC's indexed grant record lists National Natural Science Foundation of China 82201966 and Natural Science Basic Research Program of Shaanxi Province 2023JC-QN-0924 and 2023-JC-YB-787. Full conflict-of-interest statement was not retrieved; public grants do not exclude other interests.
  9. Khunger N; IADVL Task Force. Standard guidelines of care for acne surgery. Indian J Dermatol Venereol Leprol. 2008;74(Suppl):S28–36. PMID:18688101.Tier 4Supports: Indian dermatologist-focused consensus recommends extraction for predominantly comedonal acne as an adjunct to medical therapy, at its own Level D evidence grade. Warns that undue force can increase inflammation and scarring; closed-lesion removal involves opening the surface. No procedural instructions are reproduced. Not a UK authorisation or competency standard.Funding / interest: IADVL task-force document. No specific funding or conflict-of-interest declaration was located in the retrieved article text; lack of a statement is not a declaration of no conflicts.
  10. Draelos ZD, DiNardo JC. A re-evaluation of the comedogenicity concept. J Am Acad Dermatol. 2006;54(3):507–512. doi:10.1016/j.jaad.2005.11.1058. PMID:16488305.Tier 3Supports: Retrieved abstract: six selected comedone-forming volunteers; finished cosmetic products patched on upper backs for four weeks; cyanoacrylate sampling. Authors conclude that finished formulations containing ingredients classed as comedogenic are not necessarily comedogenic. Neither a facial-use trial nor a guarantee for every formula or client.Funding / interest: PubMed indexes non-US-government research support but the retrieved abstract does not identify its source or the authors' commercial interests. Publisher full text was not accessible; funding and conflicts remain unverified.
  11. Jeremy AH, Holland DB, Roberts SG, Thomson KF, Cunliffe WJ. Inflammatory events are involved in acne lesion initiation. J Invest Dermatol. 2003;121(1):20–27. doi:10.1046/j.1523-1747.2003.12321.x. PMID:12839559.Tier 3Supports: Human biopsy immunohistochemistry compared clinically uninvolved acne skin, early inflamed lesions and non-acne controls; immune/endothelial activation was detectable before visible lesion or hyperproliferative changes. The accessible abstract does not report participant count, age range, biopsy site or funding. Not an animal experiment or a treatment trial.Funding / interest: Funding and conflicts were not stated in the retrieved PubMed/Europe PMC abstract. No declaration of independence is inferred.
  12. Do TT, Zarkhin S, Orringer JS, Nemeth S, Hamilton T, Sachs D, Voorhees JJ, Kang S. Computer-assisted alignment and tracking of acne lesions indicate that most inflammatory lesions arise from comedones and de novo. J Am Acad Dermatol. 2008;58(4):603–608. doi:10.1016/j.jaad.2007.12.024. PMID:18249468.Tier 3Supports: Publisher abstract and declarations retrieved: 25 people with untreated facial acne photographed fortnightly for 12 weeks. Among inflammatory lesions, 54% were preceded by visible comedones and 28% by normal-appearing skin. Denominator is inflammatory lesions, not all comedones. Interval imaging may miss transient or very small lesions.Funding / interest: Publisher declares no funding sources and no conflicts of interest.
  13. Zelickson AS, Mottaz JH. Pigmentation of open comedones: an ultrastructural study. Arch Dermatol. 1983;119(7):567–569. doi:10.1001/archderm.1983.01650310029005. PMID:6222702.Tier 3Supports: MEDLINE abstract directly retrieved through Europe PMC core API on 16 September 2026: human expressed black comedones examined ultrastructurally; authors did not find melanosomes and disputed melanin as the explanation of the colour. Abstract does not give sample size or establish an alternative pigment quantitatively.Funding / interest: Funding and conflicts were not available in the retrieved abstract/metadata.
  14. NHS. Acne. Page last reviewed 3 January 2023.Tier 4Supports: Clinical distinction between blackheads, whiteheads, papules, pustules, nodules and cysts; blackhead colour is not dirt. Only stable morphology and public-facing care distinctions are used; current management is anchored to NICE.Funding / interest: NHS patient-information page; no commercial sponsor identified on the retrieved page.