Acne is a skin condition that starts in the hair follicles — the tiny openings most people call pores. It is extremely common: the American Academy of Dermatology (AAD) describes it as the most common skin condition in the United States, affecting up to 50 million Americans every year. Nearly everyone gets at least a few breakouts as a teenager, and plenty of people deal with it well into adulthood.
Understanding what is actually happening in your skin makes it much easier to pick a treatment that fits — and to recognize when acne needs a professional.
What happens inside a pore
Each hair follicle is connected to a sebaceous (oil) gland. Normally, the gland’s oil — sebum — travels up the follicle and out onto the skin, and dead skin cells shed away. According to the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), acne develops when sebum and dead skin cells stick together and plug the follicle instead.
That plug creates an environment where bacteria that normally live on the skin (mainly Cutibacterium acnes, formerly called Propionibacterium acnes) can multiply. The result is inflammation: redness, swelling, heat and tenderness. If the wall of a plugged follicle breaks, its contents spill into the surrounding skin and form a deeper, more inflamed spot.
So there are four overlapping processes behind acne:
- Excess oil production by the sebaceous glands.
- Clogging of the follicle by skin cells that don’t shed normally.
- Bacteria multiplying inside the blocked follicle.
- Inflammation — the body’s response to all of the above.
Diagram with four cross-sections of skin. Normal pore: a hair follicle with an oil gland, open to the surface, with oil flowing out. Whitehead: a plug of oil and skin cells fills the follicle under a thin layer of closed skin. Blackhead: the plug reaches an open pore and its exposed top is dark. Inflamed spot: the follicle is swollen, surrounded by redness, with a pus-filled top.
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Normal pore
Oil flows out
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Whitehead
Plug under closed skin
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Blackhead
Open plug darkens in air
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Inflamed spot
Papule or pustule
This is why different treatments target different things. Benzoyl peroxide mainly reduces bacteria, salicylic acid and retinoids like adapalene help unclog follicles, and prescription options can reduce oil or inflammation. It’s also why combining treatments that work on different processes is common in dermatology guidelines.
Types of acne spots
Acne isn’t one kind of bump. The AAD groups acne lesions into these main types:
| Type | What it looks like | Inflamed? | Scarring risk |
|---|---|---|---|
| Whitehead (closed comedone) | Small, flesh-colored or white bump; the pore is closed over | No | Low |
| Blackhead (open comedone) | Small bump with a dark center; the pore is open | No | Low |
| Papule | Small, red, tender bump with no visible head | Yes | Moderate |
| Pustule | Red bump with a white or yellow, pus-filled top | Yes | Moderate |
| Nodule | Large, firm, painful lump deep under the skin | Yes | High |
| Cyst | Deep, painful, pus-filled lump that can feel soft | Yes | High |
A blackhead’s dark color is not dirt. The pore is only partly blocked, and the material inside darkens when it’s exposed to air.
Most people have a mix of spot types. Very broadly, acne made up mostly of blackheads and whiteheads with a few papules or pustules is considered milder, while acne with many inflamed spots — or any nodules and cysts — is more severe and more likely to scar.
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What causes or worsens acne
According to the AAD and NIAMS, the main factors are:
- Hormones. Androgens (hormones present in everyone) increase oil production, which is why acne often starts at puberty and can flare around periods, pregnancy or menopause.
- Family history. You may be more likely to get acne — and acne scars — if your parents had it.
- Certain medicines. The AAD lists medicines that contain hormones, corticosteroids and lithium among those that can cause acne. Don’t stop a prescribed medicine on your own; talk to the prescriber.
- Stress. Stress doesn’t cause acne on its own, but studies suggest it can make existing acne worse.
- Friction and pressure. The AAD notes that anything that rubs against your skin — helmet straps, backpack straps, tight collars — can irritate it and make acne flare in those areas.
- Pore-clogging products. Heavy, greasy skin care, hair products or makeup can contribute for some people; look for products labeled “non-comedogenic” or “won’t clog pores.”
What about diet?
This is one of the most debated topics in acne. Some studies suggest certain foods may make acne worse, and research continues. But the evidence is still limited. The AAD’s 2016 acne guidelines said high-glycemic diets and dairy (especially skim milk) may play a role, yet recommended no specific dietary changes, and small trials of chocolate have pointed in different directions. Our guide to acne myths vs evidence walks through the dairy, sugar and chocolate studies one by one.
In practice: you don’t need to cut out whole food groups to treat acne. If you notice a consistent pattern with a particular food, that’s worth discussing with a clinician — but proven topical and prescription treatments should come first.
Myths worth dropping
- “Acne means you’re not washing enough.” Acne starts beneath the surface. Over-washing and scrubbing can irritate skin and make it look worse. Gentle cleansing twice a day and after sweating is usually enough.
- “Popping pimples helps them heal faster.” Squeezing can push material deeper and increase the risk of dark marks and scars.
- “Acne is just a teenage thing.” Adult acne is common — see below.
Acne in adults
It’s possible to get acne for the first time as an adult. The AAD calls this adult-onset acne and notes it is most common in women going through menopause, and that women get adult acne more often than men. Hormonal fluctuations and stress are thought to contribute.
Adult acne often appears around the lower face, jawline and chin, and adult skin can be more easily irritated by strong acne products. Sudden, severe acne in an adult — especially alongside irregular periods, excess hair growth or thinning scalp hair — can occasionally point to an underlying hormonal condition and is worth checking with a doctor.
How acne is treated
Treatment depends on what kind of spots you have, how many, how deep they are, and your own circumstances. The 2024 AAD guidelines strongly recommend benzoyl peroxide, topical retinoids, topical antibiotics and oral doxycycline, with other options — including isotretinoin — for more severe or stubborn acne.
For mild acne, many people start with over-the-counter products. In the US, the FDA’s acne drug monograph (M006) sets which active ingredients non-prescription acne drugs can contain, and at what strength:
| Active ingredient | Allowed OTC strength | Regulatory basis |
|---|---|---|
| Benzoyl peroxide | 2.5% to 10% | FDA monograph M006 |
| Salicylic acid | 0.5% to 2% | FDA monograph M006 |
| Sulfur | 3% to 10% | FDA monograph M006 |
| Sulfur + resorcinol | Sulfur 3% to 8% with resorcinol 2% (or resorcinol monoacetate 3%) | FDA monograph M006 |
| Adapalene | 0.1% gel | Approved for OTC use in 2016 through an Rx-to-OTC switch (not the monograph) |
A few practical points apply to almost every treatment:
- Give it time. The AAD says that if a treatment is working, you should notice some improvement in 4 to 6 weeks; clearing can take two to three months or longer.
- Expect some irritation at first. Dryness, peeling and stinging are common with benzoyl peroxide, salicylic acid and retinoids. Starting every other day and using a gentle moisturizer can help.
- Keep going once it works. Acne often returns when treatment stops, so many people need an ongoing maintenance routine.
- Treat early to prevent scars. The AAD recommends treating acne when breakouts first appear, especially if a close relative has acne scars.
When to see a dermatologist
Over-the-counter treatment is a reasonable place to start for mild acne, but it isn’t enough for everyone. See a dermatologist or your doctor if:
- you have deep, painful nodules or cysts;
- acne is leaving scars or dark marks;
- over-the-counter products haven’t helped after two to three months of consistent use;
- acne is affecting your mood, confidence or daily life;
- you’re pregnant, breastfeeding or trying to conceive — several acne medicines aren’t safe in pregnancy, so get advice before starting anything;
- you’re under 18 — a parent or guardian can help arrange care with a pediatrician or dermatologist;
- acne came on suddenly as an adult, or comes with other symptoms such as irregular periods or excess hair growth.
Prescription treatments — from topical retinoids and combination gels to oral medicines — are far more effective for moderate and severe acne than anything on a drugstore shelf, and treating it properly early is the best way to prevent permanent scarring.