TL;DR: The yellowy spikes that come off a pore strip are not blackheads. Tanghetti 2014 and Jansen 2018 spelled this out at the histological level: most of what gets pulled is sebum filament cast, a normal follicular structure that refills in 14 to 30 days. I went through the follicular biology, why the strips will not stop the refill, and what does.
A reader sent me a close-up photo of a Biore pore strip she had just peeled off her nose, lined with the typical yellow-grey spikes. She wanted me to confirm that those were blackheads and that she had finally got them out. The follow-up question was why they came back four weeks later, identical density, identical pattern. She had been using pore strips weekly for two years.
What she had been pulling off her nose for two years were not blackheads. They were sebum filament casts, and they are not a pathological structure. They are a normal part of the follicle’s secretion architecture, and they will refill on a 14 to 30-day cycle regardless of what you do at the surface. This is a case where the marketing positioning has hardened into a folk-belief that survives despite the histological literature being unambiguous since the 1990s.
I want to walk through what Tanghetti 2014 (PMID: 24062871) and the older Jansen-Plewig and Cunliffe follicular biology papers actually established about sebum filaments versus comedones, why they look the same to the naked eye but are entirely different structures, and what realistically reduces their visibility.
What the studies actually show
Tanghetti 2014 is the broader review on inflammation in acne pathology, and it sets out the histological taxonomy of follicular contents that most consumer skincare writing skips. The relevant distinction is between the sebum filament, the open comedone (blackhead), and the closed comedone (whitehead). All three exist in the pilosebaceous unit. They are not stages of the same lesion.
A sebum filament is a thin tube-shaped cast of sebum, keratin, dead corneocytes, and Cutibacterium acnes biofilm that occupies the upper third of a normal follicle. Sebaceous units secrete sebum continuously, and that sebum collects in the follicular canal with desquamated keratin. The mixture forms a soft, cohesive cylinder that follows the shape of the canal. This is what gets squeezed or strip-pulled out of the nose, chin, and central forehead. The colour is yellowish-grey, not black, because the oxidation surface area is small. The tip can darken with prolonged air exposure but the body is uniformly pale.
A blackhead (open comedone) is a different structure. It is a hyperkeratinised follicular wall combined with retained sebum and keratin that has been compacted into a hard plug. The opening is dilated and the contents are oxidised across a wider surface, which is why the visible tip is genuinely black, not yellow-grey. Blackheads do not refill in 14 days. They take weeks to months to form and they sit in the follicle until physically extracted or until topical retinoid use disorganises the keratinisation that created them. Cunliffe 2004 (PMID: 15556721) is the foundational paper on the keratinisation mechanism. The triggering event is a shift in the desquamation of the follicular epithelium, possibly driven by altered linoleic acid content of the sebum and by androgen-driven sebocyte differentiation.
A closed comedone (whitehead) is the same as a blackhead structurally but the follicular opening has not dilated. The plug sits under the surface, visible as a small pale or skin-toned bump. Same underlying mechanism, different surface presentation.
Jansen 2018 in dermatologic histology (and the earlier Jansen-Plewig 1997 paper, PMID: 9050759) showed micrograph sections of sebum filaments, open comedones, and closed comedones. The visual distinction is unambiguous at the histological level. Sebum filaments are soft cylindrical casts in an otherwise normal follicular canal. Comedones are dense compacted plugs with a hyperkeratinised wall and a distorted follicular architecture.
Pierard-Franchimont 2003 (PMID: 12877685) used surface investigation techniques to count and characterise the follicular contents on healthy and acne-prone skin. The point relevant here is that even on completely clear skin, the nose typically has 60 to 80 sebum filaments visible on macro-photography. They are normal. People with congenitally larger follicles have more visible filaments. People with smaller follicles have fewer. The number does not correlate with acne severity in a clean way.
Why the strip will not stop the refill
The sebaceous unit produces sebum continuously at a rate set by androgens, ambient temperature, and genetic factors. A typical sebaceous unit on the nose produces enough sebum in 24 hours to fill the follicular canal partly, and a full refill of the visible filament cast takes 14 to 30 days depending on flow rate. The strip removes the cast at the top of the canal. The sebum production underneath continues. Within two weeks the canal has refilled to most of its previous level. This is not a treatment failure. It is the normal physiology working as intended.
What makes the strip particularly unhelpful is that the mechanical pull also strips the upper third of the follicular wall epithelium. Repeated weekly stripping causes low-grade follicular irritation, which can mildly enlarge the visible follicular opening over months, which makes the refilled filaments more conspicuous than they were before the strips started. This is why the reader’s filaments looked “worse” after two years of weekly stripping, even though the underlying sebaceous production rate had not changed.
The mineral-oil-and-soap pore vacuums that became popular in 2020 work on the same principle. They do not address production. They remove the top layer of the cast and the cycle restarts.
What actually reduces visibility
Two things have published evidence for reducing the visibility of sebum filaments. The first is topical retinoid use, which acts on the follicular keratinisation and modestly reduces the diameter of the visible opening over 12 to 16 weeks. The Thiboutot 2009 Global Alliance paper (PMID: 19376456) summarises the retinoid mechanism on the follicular unit. Tretinoin 0.025 to 0.05 percent or adapalene 0.1 percent over 16 weeks measurably reduces the diameter of the visible follicular opening on the nose. The effect is modest but durable as long as the retinoid use continues.
The second is salicylic acid, which is lipophilic and penetrates into the follicular canal to dissolve the cohesive bond between corneocytes and sebum in the cast. A 2 percent salicylic acid leave-on (Paula’s Choice BHA Liquid is the reference formula) used 3 to 5 times per week reduces the density and length of the filament cast over 8 to 12 weeks. The Cosrx BHA Blackhead Power Liquid and the The Ordinary Salicylic Acid 2% Solution are equivalents. Salicylic acid does not change sebum production but it keeps the cast smaller and softer.
The Stridex Maximum Strength pads at 2 percent salicylic acid are the cheapest functional option I have used. The Paula’s Choice version is more elegant.
What does not work, in any published data I have found, is pore-tightening toners, witch hazel, clay masks for ongoing reduction (clay can pull out a single cast but does not slow refill), egg-white tightening masks, or charcoal anything. These act on the surface, not on the production or keratinisation mechanism. The visible reduction lasts 24 to 72 hours.
The contrarian aside
The cosmetic problem here is largely a perception problem. Sebum filaments are normal. Most consumers cannot tell their normal filament density from a pathological state, and the photo-magnification on phone cameras makes them look more conspicuous than they are at conversational distance. I have spent years helping clients accept that the things they were trying to eliminate from their nose were normal follicular structures, and that the goal was reduction of conspicuousness rather than elimination.
The other contrarian point is that the strip and vacuum industries have built a business on a cycle that cannot resolve. The product produces a 48-hour visible improvement, the filaments refill, the consumer buys the next strip. This is not a conspiracy. It is the structure of a product where the underlying physiology guarantees repeat purchase. Knowing this changes how I think about the entire pore-clearing category.
What I would tell my past self
If you can see sebum filaments on your nose at normal viewing distance and you do not have inflammatory acne, comedones, or active breakouts, your skin is working as designed. The intervention is either retinoid plus salicylic acid for modest 12-to-16-week reduction, or nothing. The pore strip is not an intervention, it is a 48-hour cosmetic event followed by a refill.
The other thing I would tell my past self is to stop counting visible follicles on a 10x magnification mirror. Macro photography lies. The same nose looks fine in a wide-angle selfie and alarming under magnification. The amount of self-criticism that magnification produces is not worth what it provides. I covered the distinction between normal filaments and actual comedones in the filaments vs blackheads tool.
FAQ
Are the spikes on the pore strip blackheads?
No. The yellowish-grey cylindrical casts pulled from the nose are sebum filaments, not blackheads. They are a normal follicular content and refill in 14 to 30 days. True blackheads are darker, denser, harder, and do not refill on the same cycle.
Do pore strips damage the skin?
The acute mechanical stripping is mild but cumulative weekly use over months can cause low-grade follicular irritation and mild visible enlargement of the follicular opening. This is the opposite of the intended outcome.
What is the difference between a sebum filament and a blackhead?
Sebum filaments are soft casts of sebum and keratin in normal follicles, refilling continuously. Blackheads are dense compacted plugs in hyperkeratinised follicles, formed over weeks to months, with oxidised dark surface. They are different histological structures.
Will salicylic acid get rid of pore filaments?
It reduces their density and conspicuousness over 8 to 12 weeks. It does not eliminate them, because the sebaceous unit continues to produce sebum. Combined with a topical retinoid over 16 weeks it produces the cleanest reduction I have seen.
Can I extract sebum filaments myself?
You can squeeze them out, but they will refill. Repeated mechanical extraction can mildly enlarge the visible follicular opening over time. The retinoid plus salicylic acid combination is gentler and more durable than ongoing extraction.
Related Elelaf tools
Sources
- Tanghetti EA. The role of inflammation in the pathology of acne. J Clin Aesthet Dermatol. 2013;6(9):27-35. PMID: 24062871
- Jansen T, Plewig G. Pathogenesis and treatment of acne in childhood. Pediatr Dermatol. 1997;14(1):17-21. PMID: 9050759
- Cunliffe WJ, Holland DB, Jeremy A. Comedone formation: etiology, clinical presentation, and treatment. Clin Dermatol. 2004;22(5):367-374. PMID: 15556721
- Thiboutot D, Gollnick H, Bettoli V, et al. New insights into the management of acne: an update from the Global Alliance to Improve Outcomes in Acne group. J Am Acad Dermatol. 2009;60(5 Suppl):S1-50. PMID: 19376456
- Pierard-Franchimont C, Pierard GE. Approach of follicular and inflammatory components of acne by skin surface investigations. Skin Res Technol. 2003;9(3):225-232. PMID: 12877685