Why your dermatologist or that sales person may not know what a ‘sebaceous filament’ is

You may have read a few articles recently saying that the blackheads on your nose are more properly called sebaceous filaments. But as it turns out ‘sebaceous filaments’ isn’t really a standard or common term, at least in the research and medical world.

A quick Google search from 1960 to 2010 reveals that the term came into popular use beginning in the late 2000s, mostly on acne and bodybuilding message boards.

Sebaceous filaments were defined on one site incorrectly as “oil glands” and the only scientific paper from that time-frame I found mentioning sebaceous filaments was in a British Journal of Dermatology paper – which mentioned them, but did not describe them.

Where did ‘Sebaceous Filaments’ come from?

The term sebaceous filament likely originates from around 1912 by French dermatologist Sabouraud quoted in the Journal of Cutaneous Diseases Including Syphilis where it is quoted as “seborrhoeal filaments” and presumably translated to sebaceous filament.

It’s then referenced 12 years later as sebaceous filaments in a paper by Rulison in the Archives of Dermatology and Syphilology.

These of course are looking at seborrhoel or sebaceous filaments of the scalp, but a German paper published in 1976 under Follikel-Filamente examined ones found in the skin. Sebaceous filament was then mentioned by David Whiting in his 1979 review on acne, before making its way into a book by Plewig and Kligman in 1993.

In many textbooks microcomedone, impactions, follicular casts, follicular filaments or just the contents of the infundibulum (the pore opening above the sebaceous gland) are also used to describe them.

If you do a Google Scholar search for the term “Sebaceous Filament” you only get about 15 hits, a University of Toronto literature search only returns 7.

This may be why articles from Teen Vogue and Allure have a hard time differentiating between a blackhead and a sebaceous filament. There’s arguably only one paper defining the term, the rest just use it as a descriptor.

The original German paper outlines some morphological differences and makes an argument that they are different from microcomedones and richostasis spinulosa (a condition which leads to the development of fine, dark hairs in the pore).

How are blackheads and sebaceous filaments the same?

“Sebaceous filaments are most commonly found in the centrofacial areas and the alae nasae in postpuberal individuals with large facial pores and seborrhea.”

These are also common areas for microcomedones which may turn into blackheads (more properly called open comedones).

“Sebaceous filaments are cylindrical tubes of whitish-yellowish color, which can be expressed from areas of the face rich in sebaceous follicles by pinching the skin or by the cyanoacrylat-technique.”

The cylindrical tubes are composed of bacteria, sebum, dead skin cells, and often also contain a fine hair. Blackheads or open comedones are also composed of bacteria, sebum, dead skin cells, and also often contain a fine hair.


How do blackheads and sebaceous filaments differ?

Sebaceous filaments are considered a normal feature of the skin, whereas a blackhead or open comedone is non-inflammatory acne.

Generally, blackheads or open comedones are going to be a larger buildup of sebum and dead skin cells. Blackheads or open comedones frequently distend or swell the shape of the pore. Blackheads or open comedones have an oxidized cap of melanin and lipids, giving them their dark or black appearance. Sebaceous filaments don’t always have a dark cap like blackheads, but they’re often the ones a person consider an issue, as the lighter ones can blend into the skin.

The two also seem to differ in ways that aren’t readily apparent to the human eye.

“Follicles containing sebaceous filaments have a conspicuous granular layer and no acanthosis.”

Acanthosis is a thickening of the layers of skin, and the granular layer is the stratum granulosum – the third layer of skin.

In regards to blackheads or open comedones, another group of researchers found that there was some acanthosis or thickening of the skin, and a relatively normal stratum granulosum.

The German researchers also noted that in comparison to sebaceous filaments, microcomedones had smaller sebaceous glands as well as more skin cells in areas of the hair follicle.

Another author notes that the key difference between a sebaceous filament and a blackhead is that the skin cells become “sticky” in a blackhead and agglomerate into a plug.

So what’s the takeaway?

The two are probably best imagined as being on a continuum rather than two separate categories.

Both are mostly caused by the continuous production of sebum and skin cells. Sebaceous filaments are considered a normal build-up in the pores and can lead to blackheads or open comedones.

For someone with dark sebaceous filaments on their nose or chin, knowing that it’s normal or calling them blackheads or sebaceous filaments doesn’t really matter. The goal is to reduce their appearance.

I don’t bother “correcting” people when they describe blackheads on their nose. At the end of the day, as long as both parties understand what is being talked about – it’s fine!

What’s the best way to reduce blackheads or sebaceous filaments?

Both sebaceous filaments and blackheads or open comedones can reform after a certain period of time. The German researchers suggested it was 30 days for sebaceous filaments, but anecdotal evidence suggests it may be much sooner for some people. In the case of blackheads or open comedones, if the obstruction is removed the blackhead should not reform – at least to its previous size.

Consistent removal of the debris from the upper area of a pore will reduce the appearance of both a sebaceous filament and a blackhead.

This can be done through gentle manual exfoliation, chemical exfoliation with acids like glycolic or salicylic, or retinoids (anecdotally from dermatologists I’ve spoken to tazarotene is the most effective). The main thing to keep in mind is that sebum and skin cell production is constant, so consistency is crucial to reduce their appearance. The key is to find a product that you can use frequently enough to reduce their appearance, but doesn’t cause irritation. A very strong acid may reduce or completely eliminate your blackheads or sebaceous filaments, but you may not be able to use the product again before they return.

I’ve personally found that certain surfactants are more effective than others. The two that have given me the best results are disodium laureth sulfosuccinate and decyl glucoside. These tend to perform better at removing lipids from the skin, but are less irritating than sodium lauryl sulfate.

What about nose strips, peel masks, or pore vacuums?

These tools can help remove both blackheads and sebaceous filaments by adhering to the upper layer and then pulling them out of the skin.

There’s some concern that consistent use of nose strips or peeling masks can lead to larger pores and skin damage like vein formation.

However there’s no evidence that this occurs. Pore size is associated with age, chronic UV exposure, sebum output levels, and sex, among other things. In women, pore size can also be influenced by the menstrual cycle.

But just because there’s no evidence doesn’t mean it’s not possible. Perhaps it just hasn’t been studied – on the other hand, perhaps it was studied and there was no result…so the researchers decided not to publish. There is research on tape stripping, which is a method of removing skin layer by layer with tape. After 5 tape strippings there was a very modest increase in water evaporation through the skin which is usually used as a measure of skin barrier function. More apparent and drastic effects took between 20-30 tape strippings. So it seems one use of a nose strip or peeling mask infrequently isn’t likely to cause much of an issue.

If nose strips or peel masks work really well for you, I’d recommend you keep their use to no-more than once a week, and to make sure your skin is in its best condition before using. So I would not recommend using them if you’ve recently introduced an exfoliant or are using retinoids on the skin. Right after desperately scrubbing your skin to reduce blackheads or sebaceous filaments is not a good time to use a pore strip or peel mask.

Pore vacuums are also coming back into popularity, but it’s important to keep in mind that these don’t actually vacuum up blackheads or sebaceous filaments. What they do is apply negative pressure on the skin, and this suction pressure and the additional pressure from sliding it against the sides of the device compresses the pore, expressing its contents. It’s very similar to squeezing your skin.

If you’re not convinced you can watch this Youtube video of water in a vacuum chamber. The water doesn’t get sucked up by the vacuum when it’s turned on.

So blackheads, microcomedones, impactions, sebaceous filaments, follicular filaments, follicular casts – whatever you want to call them…they’re arguably natural features of the skin, and if you’d like to reduce their appearance the treatment options are the same.