Sebaceous filaments versus blackheads: what are the differences?

Sebaceous filaments are natural filamentous structures of white to pale yellow colour that line the wall of the pores of the skin. They represent a distinct functional state of the sebaceous follicles: they help channel the flow of sebum from the sebaceous gland to the skin surface, where it protects the epidermis from dehydration and environmental stressors. Sebaceous filaments occur most often in facial areas with higher sebum secretion (sides of the nose, nasolabial fold, cheeks and forehead).

They are absent in children. They appear at puberty and become more common in adulthood. Although everyone has them, individuals with oily skin or enlarged pores are more likely to notice them. Sebaceous filaments become visible when the pore fills with sebum and expands. Follicular filaments reform within three to five weeks.

Should sebaceous filaments be extracted?

Although unsightly, sebaceous filaments are not considered imperfections In essence, they pose no harm and have no pathological significance. There is no reason to try removing them by manual removal, with the risk of causing skin inflammation from pressing on the area. This action encourages bacterial growth inside the weakened pore and may lead to a blemish.

In addition, even if you extract or squeeze your sebaceous filaments, they return within 30 days, or sooner if your skin is oily. However, it is possible to reduce their appearance by adopting an appropriate skincare routine designed to regulate sebum production and minimise pore congestion.

The blackheads, also called open comedones, are the result of a buildup of sebum, keratin, and dead cells within the hair follicle. Unlike sebaceous filaments, they appear when the pore opening is partially blocked, preventing proper sebum flow. This blockage creates an environment conducive to the oxidation of the sebum-keratin mixture on contact with air, which explains their characteristic dark shade. They are not dirt but a natural chemical reaction.

Blackheads are considered a non‐inflammatory form of acne.

Blackheads appear on the nose, forehead, chin, or back, areas with the highest concentration of sebaceous glands. They may present as single lesions or in clusters. Unlike sebaceous filaments, which are evenly distributed in pores and uniform, blackheads are localised, deeper and denser. To remove the blackheads, the first step is to avoid manipulating or dislodging them with your fingers. Fingernails harbour bacteria, which can infect the skin and worsen the condition. Better to adopt a tailored care routine that includes a cleansing gel and a suitable moisturiser, along with exfoliating and keratolytic agents such as glycolic acid and retinoids.

Sebaceous filaments are mistaken for blackheads. They look similar and appear in the same areas. These filaments coexist with blackheads on combination to oily skin, especially in the T-zone. The tip of seborrheic filaments can darken, explained by the oxidation of the fatty acids in sebum covering them on contact with air, resulting in a blackhead-like appearance. However, this oxidation remains subtle and superficial compared to that seen in open comedones.

First, the sebaceous filament is a natural structure around hair follicles, whereas a blackhead is a skin disorder resulting from pore blockage by oxidised sebum and dead cells. In other words, sebaceous filaments contribute to the skin’s physiological balance, while open comedones are linked to an imbalance in sebum production and keratinisation. The blackheads lie on the skin’s surface, whereas sebaceous filaments embed deeper in the skin without obstructing pores. They align with the follicle walls and allow normal sebum flow to the skin’s surface.

Finally, you can distinguish them with a simple test. When you extract blackheads—which you should avoid—they appear as dark plugs. By contrast, squeezing a sebaceous filament releases a thin, uniform, waxy sebum column, sometimes with a dark tip. This column retracts because the filament regenerates on its own. You do not need to remove sebaceous filaments.

• MILLS O. & al. Microbiology of comedones in acne vulgaris. Journal of Investigative Dermatology (1973).

• DABBAS D. & al. Sebaceous filaments. Dermatology Practical & Conceptual (2021).

• HSU S. & al. A case report of sebaceous filaments. Cureus (2023).