What Causes Acne? A Dermatologist Explains

The causes of acne are internal, not superficial: four factors interact inside the pore to produce a spot — it is not just "dirt" sitting on the surface of the skin. That single idea changes everything, because it explains why repeated washing does not stop breakouts, and why acne appears even on perfectly clean skin. This guide breaks down the core mechanism, then the triggers on the face and chin, and the deep pimples under the skin.

Clean skin matters, but acne does not start at the surface — it starts inside the pore, where four factors meet. Understanding those factors is what lets you choose treatment that targets the cause instead of the symptom.

What causes acne: the core mechanism

The causes of acne come down to a sequence of four steps that happen inside the pore:

Increased sebum: the oil glands produce more oil than the skin needs, usually under hormonal drive.
A blocked pore: dead skin cells stop shedding evenly, pile up, and plug the pore opening.
Bacterial growth: the skin's normal bacteria multiply inside the sebum-rich, blocked pore.
Inflammation: the immune system responds, and you see redness, swelling, and tenderness.

Disturb any one of these steps and it sets off the rest. That is why effective treatment works on more than one front: reducing oil, unblocking the pore, controlling bacteria, and calming inflammation. The diagram below shows how the triggers feed into that chain:

graph TD
  A[Triggers: hormones, genetics, stress, products] --> B[Excess sebum]
  A --> C[Pore blocked by dead cells]
  B --> D[Bacteria-friendly environment]
  C --> D
  D --> E[Inflammation inside the pore]
  E --> F[A pimple appears]

Hormones sit behind much of this sequence — especially androgens, which enlarge the oil glands and raise sebum output. That is why acne so often starts at puberty and fluctuates with the menstrual cycle and pregnancy. When that factor becomes the primary driver — deep lumps along the jawline that follow the rhythm of the month — hormonal acne and how to recognise it becomes a pattern in its own right, with a different plan behind it. Genetics plays a parallel role in deciding how active those glands are and how quickly pores block, which is why acne patterns sometimes run in families. Understanding both makes clear that part of the cause is outside your control — the goal is to manage it, not to blame yourself for it.

Acne on the face and its triggers

Once you understand the mechanism, the triggers become clearer: they are simply the things that push one or more of those four steps along. Among the biggest drivers of facial acne are the hormonal swings that activate the oil glands, and the inherited tendency that sets how active those glands are. On top of that sit daily factors you can adjust:

Trigger	How it worsens acne	What you can do
Comedogenic products	Block the pore opening	Choose non-comedogenic products
Over-washing and scrubbing	Damage the skin barrier and raise oil	Cleanse gently twice a day
Stress and poor sleep	Raise the hormones that drive oil	Regular sleep and stress relief
Touching the face and phone	Transfer bacteria and dirt	Clean the phone, touch less
High sugar intake	May worsen it for some people	An individual dietary balance

These factors do not create acne out of nothing, but they pour fuel on the fire in skin that is already prone to it. Managing them lowers both the number and the severity of spots, and it is part of any plan for understanding what causes acne in your skin specifically. If your breakouts cluster in particular zones, the pattern of pimples on your face by area can tell you which habit to target first.

Causes of chin acne

Chin acne differs a little from the rest of the face because it is the most hormone-linked. The chin and jawline are sensitive to the hormonal shifts around the menstrual cycle, so deep, recurring spots often appear there in the days before a period. Face-touching and resting the chin on a hand while working or studying add to it — a habit that carries bacteria to the area.

If chin acne comes back on a monthly rhythm as painful lumps, that is a hormonal pattern that may benefit from a medical assessment, because some cases need prescribed treatment that addresses the hormonal root.

Causes of pimples under the skin

Pimples under the skin come from deep inflammation inside the oil gland that finds no opening to the surface. When a pore blocks deep down and fills with sebum and bacteria, the immune system attacks it and a firm, painful lump forms with no head. This type is more likely in very oily skin, in people with a genetic tendency, and where hormonal swings are pronounced.

When pimples under the skin recur in the same place, it suggests a chronically blocked pore or a deeper, hormonally driven pattern. Squeezing never helps here — it pushes inflammation deeper and leaves scars.

Things wrongly blamed for acne

As important as knowing the real causes is correcting a few common ideas that get blamed for breakouts unfairly:

Poor hygiene: acne is not a sign of being dirty. Over-washing harms the skin more than it helps, and the cause starts inside the pore, not on its surface.
Chocolate alone: there is no firm evidence that one single food causes acne for everyone; any dietary effect is individual and tied to the overall pattern, not one treat.
Water alone: drinking water is good for general health, but it does not treat the inflammatory mechanism of acne by itself.
Squeezing speeds healing: the opposite is true. Squeezing drives inflammation deeper, prolongs the spot, and leaves a mark that is harder to treat later.

Fixating on these myths distracts from the real causes that deserve attention, and it leads people to blame themselves needlessly instead of directing effort towards the factors that make a genuine difference.

Frequently asked questions

What are the main causes of acne?

Acne comes from four factors interacting inside the pore: increased sebum, a pore blocked by dead skin cells, skin bacteria growing in that blockage, and then inflammation. Hormones, genetics, stress, and some products push that reaction along. Because the cause is internal at its core, surface cleansing alone is never enough on its own.

Why does chin acne appear specifically?

Chin acne is often hormonal. The chin and jawline are sensitive to the hormonal swings around the menstrual cycle that switch the oil glands into a higher gear. Frequent face-touching and resting the chin on your hand add bacteria. A monthly, deep, recurring pattern is a classic sign of a hormonal origin.

Does food cause acne?

Food is not the root cause, but some patterns can worsen acne for certain people — a lot of sugar, high-glycaemic foods, and possibly dairy. The effect is individual and varies from person to person. A balanced diet helps, but it does not replace a suitable topical treatment when acne is clearly active.

What causes recurring pimples under the skin?

Pimples under the skin come from deep inflammation inside the oil gland with no opening to the surface, usually linked to heavy oil production, hormonal swings, and a genetic tendency. When they recur in the same spot, it suggests a hormonal factor or a chronically blocked pore — cases that benefit from a medical assessment.

When to see a dermatologist

Understanding the causes of acne is a first step, but when breakouts are widespread, deep, or recurring despite you managing the daily factors, it means the root is deeper than a home routine — usually hormonal or genetic. See a clinician if your skin has not improved after two months of a steady routine, or if the spots are starting to leave marks. At InJasmine we begin by identifying the dominant cause in your case before suggesting treatment, because treating the cause works better than chasing the symptoms.