Blackheads form when a hair follicle becomes plugged with a mix of dead skin cells and oily sebum, and the plug sits close enough to the surface that exposure to air turns it dark. The process starts well below the skin’s surface, driven by a combination of excess oil production, sticky skin cells that refuse to shed on schedule, and shifts in the chemistry of sebum itself. While nearly everyone gets a blackhead at some point, the frequency and stubbornness of the problem depend on hormones, genetics, environmental exposures, and daily habits in ways that are worth understanding.
What Happens Inside the Pore
Every blackhead begins in the upper portion of a hair follicle, a region called the infundibulum. Normally, dead skin cells lining this channel flake off and get carried to the surface by the steady flow of sebum. When something goes wrong, those cells become stickier than usual and start clumping together instead of shedding. This increased cell adhesion, combined with excess keratin production, blocks the follicle opening and traps sebum behind it, forming a plug known as a comedone.1Engineered Regeneration. Molecular pathogenesis of acne and their microneedle treatments If that plug stays closed beneath the skin, you get a whitehead. If it stretches the pore wide enough that its contents are exposed to oxygen, melanin in the dead skin cells oxidizes and turns the surface dark brown or black. That discoloration is not dirt; it is a chemical reaction with air.
This plug-forming process is sometimes called hyperkeratinization, and it sits at the very start of the acne cascade. Without it, the other contributing factors like excess oil or bacterial imbalance have far less impact. Researchers consider this follicular obstruction the initial event in comedone formation, with inflammation and bacterial involvement arriving later.
Hormones and the Sebum Engine
Sebum production is largely controlled by androgens, the hormones most people associate with male puberty but that both sexes produce throughout life. Inside the sebaceous gland, an enzyme converts testosterone into a more potent form called DHT, and this conversion is two to four times more active than competing enzyme pathways in those same glands.2JAMA Dermatology. Androgen Metabolism in Sebaceous Glands From Subjects With and Without Acne The result is that sebaceous glands are primed to pump out oil whenever androgen levels rise or when the glands themselves become more sensitive to normal androgen levels.
This is why blackheads so often flare during puberty, around menstrual cycles, or during hormonal shifts like polycystic ovary syndrome. Androgen-driven sebum overproduction is considered a necessary early step in acne development and remains one of the most important treatment targets.3PubMed. The cutaneous effects of androgens and androgen-mediated sebum production and their pathophysiologic and therapeutic importance in acne vulgaris The skin itself also produces and converts androgens locally, meaning your face can amplify hormonal signals that might be perfectly normal in the bloodstream. That local hormone activity helps explain why two people with similar blood hormone levels can have very different skin.
Why Sebum Composition Matters as Much as Quantity
Producing a lot of oil is only part of the story. The makeup of that oil affects whether it clogs pores or flows through them smoothly. Sebum from acne-prone skin tends to have an altered ratio of saturated to unsaturated fatty acids, and one fatty acid in particular, linoleic acid, tends to be lower than in people without acne.4PubMed Central. Lipid mediators in acne That relative shortage of linoleic acid has been linked to the abnormal cell behavior inside the follicle that kicks off comedone formation. In one trial, applying linoleic acid directly to the skin reduced the size of early-stage comedones by roughly a quarter over a single month compared to untreated sites.5PubMed. Digital image analysis of the effect of topically applied linoleic acid on acne microcomedones
Another component of sebum, squalene, can become a problem when it oxidizes. Squalene peroxide appears to trigger both inflammation and comedone formation on its own, essentially turning a normally protective oil into a pore-clogging irritant.4PubMed Central. Lipid mediators in acne This oxidation is accelerated by UV exposure and pollution, which creates a bridge between sebum chemistry and environmental factors.
Pollution, Air Quality, and Oxidative Stress
Living in an area with heavy air pollution can worsen blackheads through a mechanism that connects directly to the squalene problem. Airborne particulate matter and gaseous pollutants generate reactive oxygen species on the skin’s surface. These reactive molecules set off a chain reaction of lipid oxidation in the skin, which triggers inflammation and feeds into the same cycle that produces comedones.6PubMed Central. Pollution and acne: is there a link? Epidemiological studies have increasingly tied air pollution exposure to worsening of acne and other inflammatory skin conditions.7PubMed Central. Air Pollution and Skin Diseases
This is not a marginal concern limited to industrial zones. Urban traffic exhaust, wildfire smoke, and even indoor pollutants from cooking or heating can contribute. If you live in a city and notice that your blackheads are worse than when you spend time in cleaner air, the connection is plausible and supported by research. Antioxidant-containing skincare may help counteract some of this oxidative damage, though the strongest defense is simply reducing how long pollutants sit on your skin through regular, gentle cleansing.
Diet and Blackheads
The relationship between food and acne was dismissed by dermatologists for decades, but recent evidence has brought it back into serious discussion. The strongest links point to two dietary patterns: high-glycemic-index foods and dairy. High-GI diets lead to spikes in blood sugar that raise insulin levels and, in turn, boost a growth signal called IGF-1. Frequent dairy consumption does the same thing. Both whey and casein, the main proteins in milk, have been associated with increased IGF-1 and insulin levels, with one trial showing that high whey consumption raised IGF-1 by about seven to eight percent over one to two years.8PubMed Central. Diet and acne: A systematic review
Why does IGF-1 matter for blackheads? It stimulates sebaceous gland activity and promotes the same kind of cell overgrowth in follicles that leads to plugs. The effect is not dramatic enough that cutting sugar or milk will clear your skin overnight, but for people whose blackheads are stubborn despite good topical care, dietary patterns are worth examining. A low-GI diet rich in whole grains, vegetables, and lean protein tends to keep insulin and IGF-1 levels more stable.
Why “Noncomedogenic” Labels Are Unreliable
If you have tried to avoid blackheads by choosing products labeled “noncomedogenic,” you may have noticed the label does not guarantee clear skin. There is a good reason for that. The original comedogenicity ratings for cosmetic ingredients came from tests on rabbit ears, and those results often did not hold up when tested on human skin. Worse, there is no standardized testing protocol or regulatory oversight requiring companies to prove a product deserves that label before printing it on the box.9JAAD Reviews. Comedogenicity in cosmeceuticals: A review of clinical relevance, regulatory gaps, and future directions
A major flaw in most comedogenicity testing is that individual ingredients are evaluated in isolation rather than in the full product formulation. An ingredient that clogs pores at full strength may behave differently when diluted and combined with other ingredients. On top of that, skin type varies enormously from person to person, so an ingredient that triggers blackheads in one individual may cause no problems for another. The practical takeaway is that the “noncomedogenic” label is more of a marketing gesture than a science-backed assurance. Pay attention to how your own skin responds to a product over a few weeks rather than trusting a label.
Pore Size and Genetic Predisposition
Some people are simply more prone to visible blackheads because of the size of their pores, and pore size is largely determined by genetics and ethnicity. A multiethnic study measuring pore density, individual pore size, and total skin surface covered by pores found that these values varied considerably across ethnic groups, generally plateaued with age, and corresponded well to how people perceived their own pore visibility.10PubMed Central. Facial skin pores: a multiethnic study Larger pores collect more sebum and dead cells, making them more susceptible to the plugging process. If you have naturally larger pores, you may need to be more diligent about prevention even if your oil production is average.
Genetics also influence sebaceous gland size, sebum production rates, and how readily your follicular lining sheds cells. Family history of persistent acne or blackheads is one of the strongest predictors of your own risk. You cannot shrink your pores beyond their genetic baseline, despite what many skincare ads claim, but you can keep them clear with consistent care.
Prevention and Treatment That Work
Preventing blackheads means addressing the two core problems: excess or altered sebum, and the sticky buildup of dead cells inside follicles. Several approaches have solid evidence behind them.
- Gentle cleansing: Washing your face removes surface oil, dead cells, and pollution residues, but the cleanser matters. Harsh surfactants can damage skin proteins and lipids, causing dryness, irritation, and barrier damage that paradoxically makes acne worse.11PubMed. Cleansing without compromise: the impact of cleansers on the skin barrier and the technology of mild cleansing A mild, pH-balanced cleanser used twice daily is enough for most people. Scrubbing harder or washing more often does not clear pores faster and can strip the skin barrier.
- Retinoids: These vitamin A derivatives are the gold standard for comedone prevention. They work by binding to specific receptors in skin cells, which normalizes the way those cells mature and shed.12PubMed Central. Retinoids: active molecules influencing skin structure formation in cosmetic and dermatological treatments Over-the-counter retinol and prescription-strength retinoids like adapalene and tretinoin both help keep follicle linings from becoming sticky and plugged. They take weeks to show results and can cause irritation at first, so starting with a low concentration a few nights per week is standard advice.
- Salicylic acid: This oil-soluble acid can penetrate into pores and dissolve the mix of sebum and dead cells that forms a plug. It is available in cleansers, toners, and leave-on treatments at concentrations typically between one and two percent. Because it works inside the pore rather than just on the skin’s surface, it is particularly suited to blackhead-prone areas like the nose and chin.
- Chemical peels: For more stubborn blackheads, superficial chemical peels applied by a professional can accelerate cell turnover across larger areas. These have been used as an adjunct treatment for acne for decades and work by encouraging the outermost layers of skin, including the follicular lining, to shed more evenly.13PubMed Central. Chemical peels in the treatment of acne: patient selection and perspectives
Consistency matters more than intensity with all of these. A gentle daily retinoid or salicylic acid routine sustained over months will outperform any aggressive weekend treatment. And because the plugging process is ongoing, blackheads tend to return once you stop preventive treatment, which makes finding a routine you can maintain long-term more valuable than finding the most powerful option.
Sun Damage and Blackheads in Later Life
Most people think of blackheads as a teenage problem, but a distinct pattern of blackheads appears in older adults who have accumulated years of sun exposure. Favre-Racouchot disease is a relatively common condition marked by clusters of large open comedones, often around the eyes and temples, embedded in sun-damaged, thickened skin.14PubMed. Favre-Racouchot disease: systematic review and possible therapeutic strategies The underlying problem is chronic UV-induced damage to the elastic fibers in the dermis. As these fibers degenerate, the support structure around follicles weakens, allowing them to dilate and fill with keratinous debris.
These sun-related blackheads look and feel different from typical adolescent comedones. They tend to be larger, deeper, and clustered in areas that get the most cumulative UV exposure. Treatment can be challenging because the underlying structural damage cannot be fully reversed. Retinoids, gentle extraction, and sometimes laser therapy are used, but the most effective strategy is prevention through long-term UV protection. If you are seeing new blackheads appearing around your eyes or temples in your fifties or sixties, sun damage rather than oily skin is the more likely explanation.
When Squeezing Becomes Compulsive
Almost everyone has squeezed a blackhead at some point, and occasional, careful extraction does not usually cause lasting harm. But for some people, the impulse to pick, squeeze, and dig at comedones and other minor blemishes becomes a repetitive behavior that creates far more damage than the original blackhead ever would. This pattern, sometimes called acne excoriée, is a form of skin picking where the person targets real or perceived acne lesions compulsively, often leaving scars and open wounds that are worse than the original spots.15American Journal of Clinical Hypnosis. Using hypnosis to facilitate resolution of psychogenic excoriations in acne excoriée
The distinction between a normal urge to extract a visible blackhead and a compulsive picking pattern is not always obvious. Signs that picking has crossed into problematic territory include spending extended time in front of a mirror extracting blemishes, creating wounds that take longer to heal than the blackhead would have, feeling unable to stop even when you know you are making things worse, and picking at skin that is not visibly blemished. If this sounds familiar, the issue is behavioral rather than dermatological, and treatments aimed at the skin alone will not address it. Cognitive behavioral therapy is the most studied approach, though other interventions including habit-reversal training have shown benefit.
The Microbial Factor
Blackheads themselves are not infections, but the bacterial environment of the skin plays a supporting role in how they develop and whether they progress into inflamed acne. The skin bacterium Cutibacterium acnes thrives in the low-oxygen, oil-rich environment inside a plugged follicle. Current research frames acne as partly driven by microbial dysbiosis, meaning not just the presence of this bacterium but an imbalance in the broader community of microbes on the skin.16PubMed Central. Rebalancing the Skin: The Microbiome, Acne Pathogenesis, and the Future of Natural and Synthetic Therapies Certain strains appear more likely to trigger inflammation than others.
For blackheads specifically, the microbial role is secondary to the physical plugging and oil buildup. But it helps explain why some people’s blackheads readily progress to red, inflamed pimples while others stay as painless dark spots for weeks. Aggressive antibacterial treatments, including overuse of benzoyl peroxide or antibiotic washes, can sometimes backfire by disrupting the skin’s microbial balance further. A targeted, moderate approach tends to work better than scorched-earth sterilization of the skin’s surface.