Blackheads form when a hair follicle gets clogged with a mix of oil and dead skin cells, and the clog stays open at the surface. That opening is what makes a blackhead different from a whitehead: the exposed material reacts with air, turning dark. The process involves your hormones, your skin’s natural oil production, and even the bacteria living on your face.
What Happens Inside the Pore
Your skin constantly produces sebum, an oily substance that keeps your skin moisturized and protected. At the same time, skin cells lining your pores are shedding and being replaced. Normally, both the oil and the dead cells travel up through the pore and wash away. A blackhead starts when that exit route gets blocked.
The blockage begins when dead skin cells (called keratinocytes) don’t shed properly. Instead of sloughing off, they stick together inside the pore, mixing with sebum to form a soft plug. If the pore stays open at the top, you get a blackhead. If it closes over, you get a whitehead. Over time, the material can harden into a denser, more solid mass, making the blackhead increasingly stubborn to remove.
The dark color isn’t dirt. When the plug of oil and skin cells sits at the surface, it’s exposed to oxygen. The sebum undergoes oxidation, similar to how a cut apple browns. Melanin granules in the dead skin cells also accumulate at the surface and darken. Together, these two processes give blackheads their characteristic brown-to-black appearance.
Why Your Oil Glands Overproduce
Hormones are the primary driver of excess sebum. Your body converts testosterone into a more potent hormone called dihydrotestosterone (DHT), which is about five times stronger at stimulating oil glands. When DHT binds to receptors in the skin, sebaceous glands ramp up production. This is why blackheads commonly appear during puberty, before menstrual periods, and during other hormonal shifts.
Some people produce normal levels of hormones in their blood but still have oily, blackhead-prone skin. This happens when the oil glands themselves are more sensitive to hormones than average, or when the enzyme that converts testosterone to DHT is more active in their skin. It’s one reason two people with identical hormone levels can have very different skin.
How Diet Plays a Role
What you eat can influence how much oil your skin produces. High-glycemic foods, the kind that spike your blood sugar quickly (white bread, sugary drinks, processed snacks), trigger a chain reaction. Your body releases more insulin, which raises levels of a growth hormone called IGF-1. IGF-1 stimulates your oil glands and promotes the kind of cell growth that clogs pores.
Dairy has a similar effect. Frequent dairy consumers tend to have higher levels of both insulin and IGF-1 compared to people who avoid it. Whey protein, a common supplement derived from milk, has been shown to raise IGF-1 levels by about 7 to 8 percent over one to two years of regular use. In one clinical study, protein calorie supplementation significantly increased the number of comedones (the medical term for blackheads and whiteheads). This doesn’t mean dairy or carbs directly cause blackheads in everyone, but for people who are already prone to them, these foods can make things worse.
Bacteria Inside the Pore
A bacterium called Cutibacterium acnes lives naturally on everyone’s skin, feeding on sebum deep inside your pores. In small numbers, it’s harmless. But when a pore is clogged and oil accumulates, these bacteria thrive. They produce enzymes that break down sebum into free fatty acids, which irritate the pore lining and can actually promote further clogging.
Research shows that the bacterial community inside a clogged pore is far more metabolically active than bacteria on the skin’s surface. The enzymes these bacteria produce damage the hair follicle and surrounding tissue, which is how a simple blackhead can eventually progress into an inflamed, red pimple. Blackheads themselves aren’t inflamed, but they create the environment where inflammation can take hold.
Blackheads vs. Sebaceous Filaments
Many people think they have blackheads on their nose when they’re actually looking at sebaceous filaments, a completely normal skin feature. The difference matters because it changes how you should handle them.
- Blackheads are a form of acne. They appear as raised, dark specks on the skin. A solid plug of oxidized oil sits at the surface and blocks the pore entirely. If you were to extract one, a dark, waxy plug would come out.
- Sebaceous filaments are not acne. They’re the natural lining of your pores, visible as flat, evenly spaced dots that are usually gray, light brown, or yellowish. There’s no plug blocking the pore. Oil flows freely through it. If you squeeze one, a thin, waxy thread emerges, but it refills within about 30 days because it’s simply part of how your skin works.
Trying to extract sebaceous filaments is pointless and can damage the skin. They’ll always come back. Blackheads, on the other hand, won’t refill in the same way once properly treated.
What Actually Clears Blackheads
Because blackheads are a buildup of oil and dead cells, the most effective treatments work by dissolving that plug or speeding up cell turnover so clogs don’t form in the first place.
Salicylic acid is a go-to ingredient because it’s oil-soluble, meaning it can penetrate into the pore and break apart the mix of sebum and dead skin. Products with 2% to 4% salicylic acid are a good starting point. It works best as a leave-on treatment (like a serum or toner) rather than a cleanser that rinses off in seconds.
Topical retinoids work differently. They increase the rate at which skin cells turn over, preventing dead cells from piling up inside the pore. Adapalene is available over the counter. Stronger retinoids like tretinoin require a prescription. Retinoids can cause dryness and peeling in the first few weeks, but this usually settles as your skin adjusts.
One thing that consistently makes blackheads worse is squeezing them at home. Without proper tools and technique, pressing on a blackhead can rupture the follicle wall beneath the skin, pushing bacteria and debris deeper into the surrounding tissue. This can trigger infection, worsen breakouts, and leave lasting marks. If you want manual extraction, a dermatologist or trained esthetician can do it safely with sterile instruments.
Why Some Skin Is More Prone
Blackhead formation isn’t just about hygiene. Pore size is largely genetic, and larger pores collect more oil. People with naturally oilier skin types produce more sebum at baseline, giving clogs more raw material to work with. Environmental factors pile on: humidity increases oil production, while air pollution deposits particles that mix with sebum at the pore’s surface, accelerating oxidation.
Certain skincare and makeup products can also contribute. Oil-based or comedogenic products sit on the skin and block pores in much the same way excess sebum does. Switching to non-comedogenic formulas won’t eliminate blackheads on its own, but it removes one contributing factor. The most effective approach combines a product that keeps pores clear (like salicylic acid or a retinoid) with habits that reduce the amount of pore-clogging material your skin has to deal with.