Blackheads are black because the material clogging the pore is exposed to air, triggering a chemical reaction called oxidation. It’s the same basic process that turns a sliced apple brown. The dark color has nothing to do with dirt, despite what the appearance might suggest.
What Actually Causes the Dark Color
A blackhead forms when a pore fills with a mix of oil (sebum) and dead skin cells. Unlike a whitehead, which has a thin layer of skin sealing it shut, a blackhead has an open surface. That opening exposes the plug directly to oxygen in the air.
When oxygen hits the oily contents of the pore, it oxidizes the fats in the sebum. This chemical change darkens the material from its original off-white or yellowish color to brown or black. The pigment melanin, which is naturally present in skin cells, also contributes. As dead skin cells accumulate in the plug, their melanin oxidizes too, deepening the color further. The result is that characteristic dark dot on the skin’s surface.
It’s Not Dirt
One of the most persistent myths about blackheads is that they’re caused by dirty skin. They aren’t. The dark color comes from lipid oxidation, not from grime settling into your pores. Research in dermatology has confirmed that poor hygiene does not cause acne, and the formation of blackheads is not due to accumulation of dirt or debris.
This matters because it changes how you should respond. Scrubbing your face harder or washing more frequently won’t prevent blackheads. The clog forms deeper in the pore than surface washing can reach, so aggressive cleaning doesn’t help and can actually irritate your skin.
How the Plug Forms in the First Place
Your skin constantly produces sebum to keep itself moisturized. At the same time, old skin cells are shed and replaced. Normally, sebum flows freely through pores to the surface. A blackhead develops when dead skin cells stick together inside the pore instead of shedding normally, mixing with sebum to create a soft plug that blocks the opening.
Hormones are the biggest driver of this process. Androgens, a group of hormones that includes testosterone, directly control how much oil your sebaceous glands produce. When androgen levels rise, they stimulate oil glands to grow larger and pump out more sebum. This is why blackheads are so common during puberty, menstrual cycles, and other hormonal shifts. But androgens aren’t the only factor. Cortisol, the stress hormone, also increases sebaceous gland activity, which helps explain why breakouts tend to worsen during stressful periods. Even insulin plays a role: elevated insulin levels stimulate the cells in oil glands to multiply.
The more sebum your skin produces, the more likely it is that a pore will become congested. Combine excess oil with skin cells that aren’t shedding properly, and you get a plug. If skin covers the plug, it stays white (a whitehead). If the surface stays open, air gets in, oxidation happens, and it turns dark.
Blackheads vs. Sebaceous Filaments
Many of the tiny dark dots you notice on your nose aren’t actually blackheads. They’re sebaceous filaments, which are a normal part of your skin’s structure. Sebaceous filaments are thin, threadlike structures that line your oil glands and help channel sebum to the skin’s surface. Everyone has them.
The difference is structural. A blackhead contains a solid plug that blocks the pore, preventing oil from flowing. A sebaceous filament has no plug, so oil moves through freely. Visually, sebaceous filaments tend to be smaller, flatter, and lighter in color, usually gray, light brown, or yellowish. Blackheads are darker, slightly raised, and more defined. If you squeeze a sebaceous filament, a thin, waxy thread comes out, while a blackhead produces a darker, firmer plug.
Sebaceous filaments refill within about 30 days no matter what you do, so trying to squeeze them out is pointless and can damage your pores.
What Helps Clear Them
Because the plug sits deeper than the skin’s surface, effective treatments work from inside the pore rather than on top of it. Two ingredients are particularly well-suited for blackheads.
Salicylic acid is oil-soluble, meaning it can penetrate into the sebum-filled pore and break down the material forming the plug. It’s found in many over-the-counter cleansers, toners, and spot treatments, typically at concentrations of 0.5% to 2%. Retinoids take a different approach: they speed up the rate at which skin cells turn over, preventing dead cells from accumulating and forming plugs in the first place. Over-the-counter retinol is a milder option, while prescription-strength retinoids are more potent. Combining both approaches addresses the problem from two angles, clearing existing clogs while preventing new ones.
What doesn’t help is squeezing blackheads yourself. Improper extraction can push bacteria deeper into the pore, damage the follicle wall, cause scarring, or trigger inflammatory acne that’s harder to treat than the original blackhead. Professional extractions performed by a licensed aesthetician or dermatologist use sterile tools and proper technique to minimize these risks.
Why Some People Get More Blackheads
Blackhead-prone skin comes down to a few factors you can’t fully control. People with naturally oilier skin produce more sebum, which increases the chance of pore congestion. Pore size also matters: larger pores have wider openings that are more likely to collect debris and become visible blackheads. Genetics determine both of these traits.
Certain products can contribute too. Heavy, oil-based moisturizers and makeup labeled “comedogenic” can add to pore congestion. Switching to non-comedogenic products won’t eliminate blackheads entirely, but it removes one contributing factor. Humidity and sweating can also temporarily increase oil on the skin’s surface, which is why blackheads often worsen in summer months.