Acne starts inside the pore: oil production rises, dead skin cells stick together, the pore blocks, and normal skin bacteria multiply behind the blockage. Hormones drive the first step, which is why teens and young adults get it most — it is biology, not poor hygiene.
Acne is one of the most common reasons young people come to see us — and one of the most misunderstood. If you’re a teenager watching it appear, a parent wondering what to do, or a student in your twenties who thought you’d have grown out of it by now, this is for you. The most important thing to know up front: acne is normal, it’s incredibly common, and it isn’t your fault.
Here’s what’s actually going on.
The short answer: it starts inside the pore
Every pore in your skin has a tiny oil gland attached to it. Acne begins when a few ordinary things line up:
- Hormones ramp up oil. Around puberty, natural hormones (androgens) tell those glands to produce more oil. Young adults can have the same effect well into their twenties.
- The pore gets blocked. Extra oil mixes with dead skin cells and plugs the opening.
- Normal skin bacteria multiply. A bacterium that lives on everyone’s skin thrives in the blocked, oily pore.
- The body responds. That triggers inflammation — the redness, swelling and tender bumps you see. When it happens deeper down, you get the larger, painful spots.
That’s the whole chain. None of the steps are about being “dirty” — they’re about biology.
Why teens and young adults get it most
The hormone surge of puberty is the main driver, which is why acne peaks in the teenage years. But it doesn’t switch off neatly at a certain age — plenty of people have it through university and into their late twenties, and some see it for the first time as adults. Many notice it flares at particular times, such as around the menstrual cycle. All of this is normal.
The myths worth ignoring
A lot of acne advice floating around is simply wrong, and some of it makes people feel bad for no reason:
- “You’re not washing enough.” Acne isn’t caused by poor hygiene, and scrubbing harder tends to irritate skin rather than help.
- “It’s the chocolate / oily food.” Diet plays a small and very individual role at most — it is not the cause.
- “You did something wrong.” You didn’t. Genetics and hormones lead the way.
What can make it worse
Some things can nudge acne along without being the root cause — family history, hormonal changes, stress, heat and sweat trapped under helmets or masks, and squeezing or picking (which can leave marks that last longer than the spot itself). Knowing your own triggers is something a doctor can help you work through.
The good news: acne is treatable
Because acne is a medical condition, it responds to medical treatment. A doctor can assess how severe yours is and put together a plan that fits you. And there’s a real reason not to just wait it out: treating acne earlier can reduce the chance of it leaving lasting marks or scars.
If your acne is bothering you — or if you’re a parent and it’s bothering your teen — that’s reason enough to have it looked at.
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Frequently asked questions
Is acne caused by poor hygiene? No. It starts inside the pore from oil, skin cells and hormones. Washing more won’t clear it, and over-washing can make skin more irritated.
Will acne just go away on its own? It often improves with age, but it can also persist for years or leave scars. Treatment helps it clear sooner and lowers the risk of lasting marks.
At what age should we see a doctor about acne? Any time it’s bothering you or isn’t improving — there’s no need to wait for it to get “bad enough.”
Related reading: Acne that won’t clear up? When to see a doctor · Skin at Belief Medical
Written by Dr Sam Lua, Belief Medical — a private GP and aesthetic practice in Singapore. About the practice. Last reviewed: August 2026.
