Pores become visible when the follicular opening is stretched wider than usual, or when the skin supporting it loses firmness. The main mechanisms are excess sebum filling and widening the pore channel, loss of collagen and elastin around the opening, thickening of the outer skin layer from sun exposure, and debris plugging the pore. Pores contain no muscle, so they do not open and close — what changes is how stretched and how well-supported they are.
What a pore actually is
Every pore is the surface opening of a hair follicle. Attached to that follicle is a sebaceous gland which produces sebum, the oil that keeps skin flexible and helps maintain its protective barrier. Pores are functional structures, not defects, and they cover almost the entire body.
They become a cosmetic concern only when the opening widens, or the skin around it slackens. At that point, the opening catches light differently and casts a small shadow, which the eye reads as a visible dot or shallow depression. This is most obvious across the T-zone forehead, nose, and chin because sebaceous glands are largest and most densely clustered there.
One clarification is worth making straight away, because it underpins a great deal of skincare folklore. Pores cannot physically open and close. They contain no muscle tissue. Warm water and steam soften the sebum sitting inside a pore, which is why extraction becomes easier afterwards, but the opening itself has not changed dimension. Cold water constricts the surrounding tissue briefly, which can make pores look momentarily tighter, but nothing structural has occurred.
Why pore size varies so much between people
Baseline pore size is largely inherited. Genetics determine sebaceous gland size, resting sebum output and skin thickness, and these differ substantially between individuals and across ethnic groups. Someone with naturally large sebaceous glands will have more visible pores at every age than someone without, regardless of how carefully they look after their skin.
This matters because it sets a realistic frame. Genetics establish the starting point; everything discussed below determines how far you drift from it. Skin type shapes how that plays out in practice, which our article on how skin type affects enlarged pores examines in more depth.
The mechanisms that make pores look larger
Excess sebum stretching the pore channel
When sebaceous glands are highly active, sebum accumulates faster than it can clear. The pore channel widens to accommodate the volume, and repeated cycles of filling and emptying gradually stretch the follicular wall.
The analogy often used is a balloon inflated repeatedly: even once deflated, it never quite returns to its original tightness. Pore walls behave similarly. This is why people with oily and combination skin tend to show pores most prominently, and why pore visibility often tracks alongside oiliness over the course of a day.
Collagen and elastin loss removes structural support
Collagen and elastin form the scaffolding that holds skin taut. As they decline with age, the skin immediately surrounding each pore loses tension and settles slightly, widening the opening’s apparent diameter and often giving it a subtly elongated, teardrop shape rather than a round one.
This explains a pattern that puzzles many people: pores becoming prominent in their thirties or forties despite skin that is no oilier than before, and sometimes drier. The driver here is structural rather than sebaceous, which also means it responds to different interventions.
Sun-induced thickening and collagen breakdown
Ultraviolet exposure does two damaging things simultaneously. It degrades collagen in the dermis, removing support from beneath. And it thickens the outer epidermal layer, causing dead cells to accumulate around pore rims and outline them more sharply.
The combined effect makes openings look both wider and more clearly defined. Because UV damage is cumulative and largely silent for years, sun exposure is frequently the largest single contributor to pore visibility in people who otherwise have well-behaved skin.
Plugging by dead cells and debris
When dead skin cells, sebum and environmental residue combine inside a pore, they form a plug. If that plug reaches the surface and oxidises on contact with air, it darkens into a blackhead. Beyond the discolouration, the plug physically distends the pore wall from within, and repeated plugging can leave the opening permanently widened.
This is also the reason squeezing is counterproductive. The mechanical force required to expel a plug damages the pore wall, and repeated trauma is one of the more reliable ways to make an opening permanently larger.
Hormonal influence on sebum output
Androgens drive sebaceous activity, so pore visibility often shifts with hormonal state — during puberty, across the menstrual cycle, in pregnancy, and in conditions such as polycystic ovary syndrome. Androgens are present in everyone, which is why this mechanism is not confined to one sex.
What is happening here is worth stating precisely: the pore is responding to changed oil production rather than changing on its own. Address the sebum and the pore follows.
Skincare that works against the skin barrier
Heavy, comedogenic products contribute directly to plugging. Less obviously, over-washing and aggressive scrubbing strip the barrier and can prompt compensatory oil production — the skin responds to being stripped by producing more sebum, which feeds the original problem.
Several everyday habits make pores look worse rather than better, and our guide to common mistakes that make open pores worse covers the ones people most often get wrong.
Why visible pores change how skin looks overall
Enlarged openings scatter light unevenly. Skin that is otherwise healthy can therefore read as rough or dull, because the surface no longer reflects light in a uniform way. Makeup tends to settle into the openings and emphasise them rather than disguise them, which is why heavier coverage frequently makes the problem more obvious.
There is a functional consequence too. Persistently plugged pores predispose skin to comedones and inflammatory breakouts, which is why pore visibility and acne so often appear together and reinforce one another.
What can be influenced and what cannot
The inherited component of pore size cannot be changed. What can be influenced is everything layered on top of it: sebum control, collagen support, sun protection and keeping the pore clear.
Daily skincare addresses the surface drivers effectively, particularly congestion and oil. The specific actives worth using, and the concentrations that matter, are set out in our guide to ingredients that reduce the appearance of pores.
Structural stretching that has already occurred generally does not reverse with topical products alone, because the change is in the dermis rather than at the surface. Where that is the dominant driver, in-clinic procedures that stimulate collagen or resurface the skin are the usual route — how each of those actually works is explained in our article on How Professional Open Pore Treatments Work. Whether any of them suits your skin depends on an individual assessment, and you can read about the professional open pores treatments available at our clinic and what an assessment involves.
Frequently asked questions
Do pores really open and close?
No. Pores contain no muscle tissue, so they cannot open or close. Heat softens the sebum inside them, which changes how they look and feel, but the opening itself does not change size.
Why did my pores become visible only recently?
The most common explanations are declining collagen with age and accumulated sun damage. Both reduce the support around the opening without any change in how oily your skin is.
Are visible pores a sign that my skin is not clean?
No. Pore visibility is driven by anatomy, oil production, and skin structure. Over-cleansing in response usually makes it worse by damaging the barrier and triggering more oil production.
Why are pores most obvious on the nose?
Sebaceous glands are largest and most densely distributed across the T-zone, so more sebum passes through those follicles and the channels are naturally wider to begin with.
Does dehydrated skin make pores look bigger?
It can. Dehydrated skin looks less plump, so the surrounding surface is less smooth and openings become more noticeable by contrast. Dehydration can also prompt additional oil production.
Can pore size change during the day?
Apparent size can shift with oil production, humidity, and hydration. The pore itself is not changing; what changes is how much sebum is filling it and how the surrounding skin is sitting.