Acne is a skin condition where hair follicles become clogged with oil and dead skin cells, leading to pimples, blackheads, and deeper lumps on the face, chest, back, and shoulders. It affects roughly 85% of people between ages 12 and 25, making it one of the most common skin conditions in the world. While it peaks during the teenage years, acne persists into adulthood for many people, affecting up to 20% of women and 8% of men well past their twenties.
How Acne Forms
Four things happen inside a pore to create an acne breakout. First, skin cells lining the hair follicle start multiplying too quickly and don’t shed the way they normally would. This creates a tiny plug deep in the pore, invisible to the naked eye. Second, oil glands attached to the follicle ramp up production and fill the space behind that plug. Third, a bacterium that naturally lives on your skin thrives in this oily, low-oxygen environment and begins multiplying. Fourth, your immune system reacts to the bacterial overgrowth, triggering redness, swelling, and tenderness.
Every acne lesion starts with that microscopic plug. Whether it turns into a small blackhead or a painful cyst depends on how much oil accumulates, how aggressively the bacteria multiply, and how strongly your body’s inflammatory response kicks in.
The Role of Hormones
Hormones are the main reason acne surges during puberty and why it can flare around menstrual cycles, pregnancy, or times of stress. Androgens, a group of hormones that includes testosterone, stimulate oil glands to grow larger and produce more oil. The key player is a potent form of testosterone called dihydrotestosterone (DHT), which binds directly to receptors on oil-producing cells and triggers them to churn out excess oil and store more fat within the gland.
Insulin and a related growth signal called insulin-like growth factor (IGF-1) also play a role. When insulin levels spike, they can amplify the effect androgens have on oil glands, which is one reason diet sometimes enters the conversation around acne management.
Types of Acne Lesions
Acne lesions fall into two broad categories: non-inflammatory and inflammatory.
Non-inflammatory acne includes whiteheads and blackheads, both of which are types of clogged pores called comedones. A whitehead is a closed plug where the contents aren’t exposed to air. A blackhead is an open plug where the material inside oxidizes and turns dark. Despite the color, blackheads have nothing to do with dirt.
Inflammatory acne is what most people think of when they picture a breakout:
- Papules are small red or tender bumps without a visible center of pus.
- Pustules are similar bumps that fill with whitish or yellowish pus.
- Nodules are larger, deeper, and more painful lumps that sit well below the skin’s surface.
- Cysts are deep, fluid-filled lesions that can cause significant pain and are most likely to leave scars.
Most people experience a mix of these at any given time. Mild acne typically involves comedones with a few papules, moderate acne adds more widespread papules and pustules, and severe acne includes nodules or cysts.
What Makes Acne Worse
Genetics are the strongest predictor. If both of your parents had acne, your chances of developing it are significantly higher. Beyond that, several factors can trigger or worsen breakouts.
Hormonal shifts are a major driver, which is why many women notice flares in the days before their period. Stress raises cortisol levels, which can increase oil production. Friction from helmets, tight clothing, or resting your face on your hands can push bacteria and oil deeper into pores. Certain cosmetics and hair products, especially oil-based ones, can block follicles.
Diet is frequently discussed, but the evidence is weaker than many people assume. A large meta-analysis examining high-glycemic diets (foods that spike blood sugar quickly, like white bread and sugary drinks) found only a tiny, statistically insignificant effect on acne severity. The same analysis found no meaningful link between dairy consumption and acne risk. That doesn’t mean diet is irrelevant for every individual, but it’s unlikely to be the primary cause of most breakouts.
Common Treatments
Treatment depends on acne severity, but the core goal is the same: unclog pores, reduce oil, kill bacteria, and calm inflammation.
For mild acne, over-the-counter products are often enough. Benzoyl peroxide kills acne-causing bacteria, reduces inflammation, and helps clear clogged pores. It comes in concentrations ranging from 2.5% to 10%, but research shows the lower concentrations work nearly as well with less irritation and dryness. You can find it in cleansers, gels, and spot treatments.
Retinoids, which are vitamin A derivatives, work by normalizing the way skin cells grow and shed inside the follicle, preventing the tiny plugs that start the whole process. Over-the-counter retinol is milder, while prescription-strength retinoids are more potent. Both can cause peeling and sensitivity when you first start using them, but this typically settles within a few weeks.
For moderate to severe acne, a dermatologist may add prescription options. These can include stronger topical treatments, oral antibiotics to reduce bacterial levels and inflammation, or hormonal therapies for women whose breakouts are closely tied to their menstrual cycle. A newer option is a topical cream that works by blocking androgen receptors directly on the skin, reducing oil production at the source without affecting hormone levels throughout the body. It’s approved for people 12 and older.
For the most severe, scarring acne, there are stronger systemic treatments available through a dermatologist that require close monitoring but can produce long-lasting clearance.
Scarring and Dark Spots
Acne can leave marks behind even after the breakout heals, and the two main types are quite different.
Dark spots, known as post-inflammatory hyperpigmentation, are flat discolored patches that appear after a pimple heals. They’re not true scars and will fade on their own over weeks to months, especially with consistent sun protection. They’re more common and more noticeable in darker skin tones. Picking at acne or letting severe inflammation go untreated makes them more likely.
True acne scars involve actual changes to the structure of your skin. Atrophic scars are flat, shallow depressions where the skin lost tissue during healing. These are the most common type and include the “ice pick” and “boxcar” patterns many people recognize. Hypertrophic and keloid scars go in the opposite direction: the body overproduces scar tissue, creating raised, firm bumps where the acne used to be. Nodular and cystic acne carry the highest risk of permanent scarring, which is one reason early treatment of severe breakouts matters.
Why Acne Persists Into Adulthood
Many people expect acne to disappear after their teenage years, but adult acne is remarkably common. It tends to look different from adolescent acne. Teenagers often get widespread breakouts across the forehead, nose, and cheeks. Adults, particularly women, are more likely to see deeper, tender bumps concentrated along the jawline and chin, often tied to hormonal fluctuations.
Adult acne can also be more stubborn because the skin is simultaneously dealing with dryness or sensitivity, making aggressive treatments harder to tolerate. Products that worked at 16 may be too harsh at 35, and finding the right balance between treating breakouts and maintaining skin comfort often requires adjusting your approach.