Blackheads form when a hair follicle gets clogged with a mix of dead skin cells and sebum, the oily substance your skin naturally produces. The clog sits in an open pore, and when it’s exposed to air, it oxidizes and turns dark brown or black. That dark color is not dirt. It’s a chemical reaction, similar to how a sliced apple browns when left on the counter.
How a Blackhead Forms Inside the Pore
Every pore on your skin contains a hair follicle and a tiny oil gland. That gland produces sebum, which normally travels up through the pore and spreads across the skin’s surface to keep it moisturized. Problems start when dead skin cells don’t shed properly. Instead of sloughing off, they stick together inside the follicle and mix with sebum, creating a plug.
If the pore stays open at the surface, you get a blackhead (an open comedo). If skin closes over the top of the plug, you get a whitehead (a closed comedo). The distinction matters because it explains the color. A blackhead isn’t a deeper or more severe blockage. It’s simply exposed to oxygen. The sebum and skin cell mixture oxidizes on contact with air, darkening over time. The longer the material sits in the pore, the darker it gets.
Why Some People Get More Blackheads
Several factors determine whether your pores clog easily or stay relatively clear.
Excess sebum production. People whose oil glands are more active produce more material that can get trapped. Oily skin types tend to develop blackheads more frequently, especially in the T-zone (forehead, nose, and chin), where oil glands are densest.
Abnormal skin cell turnover. Your skin constantly sheds dead cells. In some people, the protein keratin (which makes up hair, skin, and nails) forms abnormally, causing cells to clump together rather than shedding individually. This makes plugs more likely.
Hormones. Androgens, a group of hormones that includes testosterone, directly stimulate oil glands to produce more sebum. This is why blackheads often first appear during puberty and can flare during menstrual cycles, pregnancy, or other hormonal shifts.
Bacteria. A specific type of skin bacterium that contributes to acne can increase inflammation inside the follicle, making clogs more likely to form and persist.
Genetics Play a Major Role
If your parents had acne, your chances of dealing with it are significantly higher. Research on twins estimates that 50 to 90 percent of acne susceptibility comes down to genetic variation. A large UK study involving 400 twin pairs found that 81 percent of acne could be attributed to genetic factors rather than environmental ones.
The numbers from family studies are striking. About a quarter of twins with acne reported one or both parents also had a history of acne, compared to just 4 percent of twins without acne. And 41 percent of twins with acne went on to have children who also developed the condition, versus 17 percent of acne-free twins. What you inherit isn’t blackheads themselves but the traits that cause them: pore size, oil production levels, and how your skin cells behave inside the follicle.
The Dirt Myth
One of the most persistent misconceptions about blackheads is that they’re caused by dirty skin. The dark color looks like embedded grime, so the assumption feels logical. But it’s wrong. Blackheads are not a sign of poor hygiene. The dark plug is oxidized oil and skin cells, not external dirt that settled into your pores.
This myth causes real harm because it leads people to scrub their faces aggressively or wash excessively. Abrasive scrubbing can damage the skin’s surface and actually increase the inflammation that triggers more breakouts. Washing your face twice a day with a gentle cleanser is enough to manage surface oil without stripping or irritating the skin.
How Diet Influences Oil Production
What you eat can affect how much oil your skin produces, particularly through its effect on blood sugar. High-glycemic foods (white bread, sugary drinks, pastries, white rice) cause rapid blood sugar spikes. Those spikes trigger two things: inflammation throughout the body and increased sebum production. Both contribute to clogged pores.
The American Academy of Dermatology notes that a low-glycemic diet may reduce acne by eliminating these blood sugar spikes. That means swapping refined carbohydrates for whole grains, vegetables, and proteins that release energy more slowly. This won’t eliminate blackheads on its own, but for people who eat a lot of processed or sugary foods, dietary changes can reduce the amount of oil their skin puts out.
Skincare Products That Clog Pores
Some of the products you use to take care of your skin may be contributing to blackheads. Ingredients labeled “comedogenic” are known to block pores. These include certain forms of lanolin, some plant-derived waxes, and various fatty alcohols commonly found in moisturizers, sunscreens, and foundations.
The tricky part is that no government agency regulates comedogenicity claims. A product can be marketed as “non-comedogenic” or “won’t clog pores” while still containing pore-clogging ingredients. Some brands argue that the overall formulation changes how individual ingredients behave, but the inherent comedogenic properties of an ingredient remain the same regardless of what it’s mixed with. If you’re prone to blackheads, checking ingredient lists rather than trusting front-of-package claims gives you more reliable information. Look for oil-free or water-based formulations, and pay attention to whether new products coincide with fresh breakouts.
Where Blackheads Typically Appear
Blackheads concentrate in areas with the highest density of oil glands. The nose is the most common spot, followed by the chin, forehead, and cheeks. They can also appear on the back, chest, shoulders, and even the ears. These areas all share the trait of having larger or more active pores.
Pore size is partly genetic and partly influenced by age and sun damage. As skin loses elasticity over time, pores can appear larger and become more prone to accumulating debris. Sun exposure accelerates this process by breaking down collagen around the pore walls, making them less likely to stay clear on their own.