Big pores are primarily caused by excess oil production, and the more oil your skin makes, the larger your pores tend to appear. Age, hormones, sun damage, and clogged follicles also play significant roles. Understanding what’s actually driving your visible pores can help you target the right factors.
To put some numbers on it: the tiny openings of hair follicles and oil glands on your face are naturally 40 to 80 micrometers across, far too small to see. What we call “big pores” are visibly enlarged openings ranging from 250 to 500 micrometers, roughly five to ten times the size of a normal follicular opening. Several forces push pores into that visible range.
Oil Production Is the Biggest Factor
Of all the variables linked to pore size, sebum output has the strongest correlation. A regression analysis of pore size found that the amount of oil your skin produces matters more than age or sex in determining how large your pores appear. The relationship is straightforward: sebaceous glands sit beneath each pore, and when they pump out more oil, the channel that carries that oil to the surface stretches wider over time.
Men tend to produce more sebum than women, which is why they generally have larger, more visible pores. The correlation between oil output and pore size is also stronger in men (r = 0.47) than in women (r = 0.38), meaning oil production is an even more dominant driver of pore size on male skin.
How Hormones Ramp Up Oil Production
Your sebaceous glands don’t just randomly decide to make more oil. They take orders from hormones, especially androgens like testosterone and its more potent form, 5-alpha-DHT. Sebaceous gland cells contain all the enzymes needed to convert testosterone into 5-alpha-DHT, which binds to receptors inside those cells and ramps up oil synthesis. People with acne produce higher rates of both hormones in their skin compared to people with clear skin.
This is why pores often look larger during puberty, around menstrual cycles, and in conditions involving elevated androgens like polycystic ovary syndrome. It’s also why men, who have higher circulating testosterone, typically have more visible pores than women of the same age.
Stress hormones play a role too. Corticotropin-releasing hormone, the molecule your body produces at the start of the stress response, directly stimulates oil production in sebaceous glands. Substance P, a neuropeptide also triggered by stress, can increase the physical size of sebaceous glands themselves. So chronic stress doesn’t just feel like it makes your skin oilier. It genuinely does.
Aging Weakens the Scaffolding Around Pores
Collagen is the structural protein that keeps skin firm, and it forms a kind of scaffold around each pore opening. As you age, enzymes called matrix metalloproteinases chew through collagen fibers in the deeper layers of your skin. The result is thinner collagen bundles, wider gaps between those bundles, and a general disorganization of the support structure that once held pores taut.
This is why pores can appear larger in your 30s and 40s even if your skin isn’t particularly oily. The pore itself hasn’t necessarily grown, but the collagen framework around it has weakened enough that the opening sags and looks bigger. Aged skin also becomes stiffer and rougher at the microscopic level, which changes how light interacts with pore openings and makes them more visually prominent.
Sun Damage Compounds the Problem
UV exposure accelerates the same collagen breakdown that happens with natural aging, but it adds another layer of damage. Chronic sun exposure triggers the skin to produce excess elastin and related proteins, but these fibers assemble incorrectly. Instead of forming a resilient elastic network, they accumulate as thick, disorganized clumps of dysfunctional material in the upper and middle layers of the skin. This condition, called solar elastosis, disrupts the normal architecture of the skin surrounding each pore.
At the same time, UV light ramps up enzyme activity that degrades both collagen and the molecules that help skin retain moisture, like hyaluronan. The combined loss of structural support and hydration leaves pore openings with less surrounding tissue to keep them small and tight. People with significant sun exposure on their face often notice that pores are largest in the areas that get the most UV, particularly the nose and cheeks.
Clogged Pores Physically Stretch Open
When dead skin cells don’t shed normally, they accumulate inside the pore along with sebum, forming a plug. This starts microscopically small, but as more material builds up, it physically stretches the follicular wall outward. With continuous distension, the pore opening gradually expands, eventually becoming an open comedone, what most people recognize as a blackhead.
This stretching can be partly permanent. A pore that has been dilated by a large plug for weeks or months may not fully snap back to its original size after the blockage clears, especially if the surrounding collagen has already been weakened by aging or sun damage. This is one reason why people with a history of blackheads or acne often have persistently larger pores in those areas even after breakouts resolve.
Diet and Blood Sugar
High-glycemic foods, those that spike your blood sugar quickly, trigger a cascade that ends at your oil glands. When blood sugar rises sharply, your body releases more insulin and a related hormone called IGF-1. In sebaceous gland cells, IGF-1 activates a signaling pathway that directly increases oil production. Clinical studies have confirmed that people with more severe acne tend to have higher levels of IGF-1 in their blood, and that a low-glycemic diet can measurably shrink sebaceous glands and reduce inflammatory breakouts.
This doesn’t mean sugar directly “opens” your pores. The mechanism is indirect: a consistently high-glycemic diet keeps IGF-1 elevated, which keeps oil production high, which keeps pores stretched. The effect is gradual and cumulative rather than immediate.
Who Gets Bigger Pores
Some factors that influence pore size are outside your control. Men have larger pores than women on average, driven by higher androgen levels and greater sebum output. Pore size also increases with age in both sexes, though the underlying cause shifts from oil production in younger people to collagen loss in older adults.
Ethnicity plays a role as well. A multiethnic study measuring pore density and size found meaningful differences across racial groups, though individual variation within any group is wide. Skin that is naturally oilier, regardless of ethnicity, will tend toward larger visible pores.
What You Can Realistically Change
Since oil production is the dominant factor, targeting sebum is the most effective approach. Topical niacinamide (vitamin B3) at a 2% concentration has been shown to significantly reduce oil output within two to four weeks of daily use. Retinoids, available both over the counter and by prescription, help normalize the shedding of dead skin cells inside the pore, reducing the buildup that stretches pores open. They also stimulate collagen production over months of consistent use, addressing the structural side of the equation.
Sun protection directly slows the collagen and elastin damage that makes pores look larger with age. Dietary changes, specifically reducing high-glycemic foods like white bread, sugary drinks, and processed snacks, can lower IGF-1 levels enough to meaningfully reduce oil production over time. None of these approaches will shrink a pore to invisible, but they address the specific biological mechanisms that make pores enlarge in the first place.