Blackheads and whiteheads form when a hair follicle gets plugged with a mix of oil and dead skin cells. The difference between the two comes down to whether that plug is exposed to air. Understanding what drives this process helps explain why some people get them constantly while others rarely do.
How a Clogged Pore Forms
Your skin constantly sheds dead cells. Normally, these cells travel up through the hair follicle and flake off the surface without you noticing. But sometimes the cells inside the follicle become sticky and cohesive, clumping together instead of shedding. This process, called hyperkeratinization, creates a tiny plug deep in the pore that isn’t visible to the naked eye.
At the same time, the oil glands attached to that follicle are pumping out sebum, a waxy substance that moisturizes your skin. When the dead-cell plug blocks the exit, sebum backs up behind it. The combination of trapped oil and compacted skin cells forms what dermatologists call a comedone. Every blackhead and whitehead starts as one of these microscopic blockages, and which type you end up with depends on what happens next.
Why Blackheads Are Dark and Whiteheads Stay Light
If the plugged follicle remains open at the surface, air reaches the trapped material. Oxygen triggers a chemical reaction with melanin (the pigment naturally present in your skin cells) and the sebum itself, turning the plug dark brown or black. This is a blackhead, or open comedone. The color has nothing to do with dirt. You could scrub your face raw and the blackhead would still be dark, because the discoloration comes from oxidation happening inside the pore.
A whitehead forms when a thin layer of skin grows over the opening of the clogged follicle, sealing it shut. Without air exposure, no oxidation occurs, and the plug stays white or flesh-toned. Because whiteheads are closed, they often feel like small, firm bumps under the surface rather than the flat, speckled appearance of blackheads.
Hormones and Oil Production
The single biggest factor behind excess oil is hormones, specifically androgens like testosterone. Androgens directly stimulate your oil glands to ramp up sebum production. This is why blackheads and whiteheads often appear for the first time during puberty, when androgen levels surge. Your body converts testosterone into a more potent form called DHT right inside the oil gland itself, which accelerates sebum output even further. Men tend to have higher levels of both the hormone receptors and the enzymes needed for this conversion, which is one reason acne is often more severe in males during adolescence.
Hormonal fluctuations don’t stop after puberty. Menstrual cycles, pregnancy, polycystic ovary syndrome, and stopping or starting hormonal birth control can all shift the balance. Estrogen has the opposite effect of testosterone on oil glands, helping to suppress sebum. When estrogen drops (right before a period, for example, or during perimenopause), the relative influence of androgens increases, and breakouts follow.
How Diet Affects Your Pores
High-glycemic foods like white bread, sugary drinks, and processed snacks cause a rapid spike in blood sugar, which in turn raises levels of insulin and a related hormone called insulin-like growth factor 1 (IGF-1). IGF-1 acts directly on oil gland cells, switching on a signaling pathway that increases fat production inside the gland. Essentially, it tells your sebaceous glands to make more oil at the cellular level. Research published in the Journal of Investigative Dermatology confirmed that IGF-1 activates a specific chain of signals in oil gland cells that boosts lipid production.
IGF-1 also works synergistically with androgens. When both are elevated, the effect on sebum output is greater than either one alone. This helps explain why some people notice breakouts after periods of eating lots of refined carbohydrates or dairy (which also raises IGF-1 levels). Swapping high-glycemic foods for whole grains, vegetables, and lean proteins won’t cure comedonal acne on its own, but it can reduce one of the hormonal signals driving oil overproduction.
Weather, Humidity, and Product Buildup
Hot, humid environments push oil glands to produce more sebum. That extra oil mixes with sweat, environmental grime, and the dead skin cells already sitting on your face, creating ideal conditions for pore blockages. Summer breakouts are common for this reason. Friction from sweaty clothing, backpack straps, or sports helmets compounds the problem on the shoulders, back, and forehead.
The products you put on your skin matter too. Thick, occlusive moisturizers and heavy makeup can physically trap moisture and oil against the skin, mimicking the same effect as a closed pore. Face masks create a warm, humid microenvironment over the lower face that promotes the same kind of congestion. If you’re prone to blackheads and whiteheads, look for products labeled non-comedogenic, which means they’ve been formulated to avoid blocking pores.
Other Contributing Factors
Some people are simply more prone to comedones because of genetics. If your parents dealt with persistent blackheads or acne, you likely inherited oil glands that are larger, more active, or more sensitive to hormonal signals. Pore size is also largely genetic, and larger pores collect more debris.
Stress plays a role too, though indirectly. Stress hormones like cortisol can increase androgen activity, nudging oil production upward. Lack of sleep and chronic stress also impair your skin’s ability to turn over cells efficiently, which can worsen the dead-cell buildup that starts the whole process.
Certain medications, including some steroids and lithium, are known to increase comedone formation as a side effect. If you’ve noticed new breakouts after starting a medication, it’s worth flagging with your prescriber.
How Long They Take to Clear
Because comedones form deep inside the follicle, they don’t respond overnight to any treatment. Topical treatments that speed up cell turnover and prevent dead cells from clumping together are the standard approach. With consistent use, you can expect to start seeing improvement in 8 to 12 weeks, but full clearance often takes several months. This timeline frustrates a lot of people, and it’s the most common reason they abandon treatment too early.
The lag exists because treatment works on the comedones forming right now, not the ones already visible on your skin. Existing plugs need time to work their way to the surface and clear. Sticking with a routine through that initial period where nothing seems to be changing is the most important thing you can do. If your blackheads and whiteheads haven’t budged after three to four months of consistent care, a dermatologist can adjust your approach or look for underlying factors you might be missing.