Blackheads form when a pore becomes clogged with a mix of oil and dead skin cells, and the surface of that plug stays open to the air. The exposure to oxygen turns the plug dark, giving blackheads their name. They’re the most basic form of acne, technically called open comedones, and nearly everyone gets them at some point. Up to 58% of adolescents and young adults experience acne, and about 20% of adult women and 8% of adult men continue dealing with it well beyond their teenage years.
What Happens Inside the Pore
Every pore on your face sits at the top of a tiny channel called a pilosebaceous duct, which houses a hair follicle and an oil-producing gland. Under normal conditions, the gland releases oil (sebum) that travels up through the duct and spreads across the skin’s surface. Dead skin cells lining the duct shed regularly, getting carried out with the oil.
A blackhead starts forming when two things go wrong at once. First, the oil gland ramps up production and pumps out more sebum than the duct can clear. Second, the skin cells lining the inside of the duct start behaving abnormally. Instead of shedding one by one and flowing out with the oil, they become sticky and clump together. This process, called follicular hyperkeratinization, means the cells don’t release from the duct wall the way they should. The combination of excess oil and clumped-together cells creates a physical plug that blocks the opening of the pore.
This plug starts as a microscopic blockage, sometimes called a microcomedone. It’s invisible to the naked eye but represents the earliest stage of every blackhead, whitehead, and pimple. If the plug stays beneath a closed layer of skin, it becomes a whitehead. If the pore remains open at the surface, it becomes a blackhead.
Why the Plug Turns Black
The dark color of a blackhead is not dirt. It’s the result of a chemical reaction between the material in the plug and the air. When the oily mixture sits at the surface of an open pore, atmospheric oxygen reacts with the fats in the sebum, changing their color through oxidation. Think of it like a sliced apple turning brown after sitting on the counter.
Oxidation isn’t the only contributor. The skin cells (keratinocytes) lining the hair follicle also produce melanin, the same pigment responsible for skin and hair color. That dark pigment gets mixed into the plug material, deepening the blackish appearance. So the color comes from two sources working together: oxidized oil and melanin from the follicle lining.
What Triggers Excess Oil and Cell Buildup
Several factors push oil glands into overdrive or disrupt normal cell shedding.
Hormones
Androgens, the hormones that surge during puberty, directly stimulate oil glands to enlarge and produce more sebum. This is why blackheads often first appear in the early teenage years. Hormonal fluctuations during menstrual cycles, pregnancy, and perimenopause explain why adult women are more than twice as likely as adult men to deal with ongoing acne.
Diet
What you eat can influence how much oil your skin produces and even what kind of oil it makes. Diets high in rapidly absorbed carbohydrates (white bread, sugary drinks, processed snacks) raise blood sugar and insulin levels quickly. That insulin spike appears to stimulate sebum production. In one controlled trial, participants who switched to a low-glycemic diet for 12 weeks saw changes in the fatty acid composition of their skin oil that correlated with fewer acne lesions. Animal studies have also shown that certain fatty acids can trigger the same kind of abnormal cell buildup inside follicles that leads to comedone formation.
Skin Products and Environment
Heavy moisturizers, sunscreens, or makeup labeled “comedogenic” contain ingredients that can physically block pores or promote the same sticky cell behavior happening inside the duct. Humidity and sweating can also trap sebum at the skin’s surface, giving plugs more material to work with. If you notice blackheads concentrated along your hairline, chin strap area, or where you rest your phone, friction and occlusion from those contact points are likely contributing.
Blackheads vs. Other Acne Lesions
Blackheads are classified as non-inflammatory acne. The plug sits in the pore without triggering an immune response, so there’s no redness, swelling, or pain. A whitehead is the same type of lesion with one difference: the pore opening is sealed over, keeping air out and preventing oxidation.
When bacteria trapped behind a plug begin to multiply, the immune system responds, and the area becomes red and tender. That’s a papule. If pus accumulates, it becomes a pustule. All of these inflammatory lesions originate as comedones. A blackhead that gets squeezed aggressively or irritated can transition into an inflamed pimple, which is why gentle treatment matters.
Where Blackheads Concentrate and Why
The nose, chin, and forehead (the T-zone) have the highest density of oil glands on the face, which is why blackheads cluster there. The nose alone has thousands of pores packed into a small area, and the glands beneath them tend to be larger and more active than those on the cheeks. Some people also get blackheads on the chest, back, and shoulders, where oil glands are similarly concentrated.
Pore size plays a role too. Larger pores have wider openings, making them more likely to stay open at the surface and form blackheads rather than whiteheads. Genetics largely determine your pore size and baseline oil production, which is why blackhead-prone skin often runs in families.
What Actually Helps Clear Them
Because blackheads form from sticky dead cells and excess oil, effective treatments target one or both of those problems. Salicylic acid is oil-soluble, meaning it can penetrate into the pore lining and help dissolve the glue holding dead cells together. Retinoids (available over the counter as adapalene or by prescription) work differently: they speed up cell turnover so that cells shed normally instead of clumping. Both approaches take weeks of consistent use before pores begin to clear, since they work on the formation process rather than removing existing plugs.
Pore strips and manual extraction can pull out the visible plug, but without addressing the underlying oil production or cell behavior, the pore typically refills within days to weeks. If you choose extraction, a clean tool and gentle pressure reduce the risk of pushing debris deeper or triggering inflammation.
For persistent blackheads that don’t respond to over-the-counter products, professional treatments like chemical peels or in-office extractions can help. A low-glycemic diet won’t eliminate blackheads on its own, but reducing blood sugar spikes may lower the oil production that feeds the cycle. Choosing non-comedogenic skin products and washing your face after sweating removes some of the external contributors, giving treatments a better chance of working.