Acne Explained: Causes, Types, and What Actually Helps

From excess oil and clogged pores to hormones and the microbiome, here is an informed look at why acne develops and how to navigate it.

What Causes Acne and How to Improve It

The skin’s structure is built around tiny hair follicle units, each pairing a follicle with its own oil gland. A pore is simply the opening of this system at the surface. Inside the follicle, the walls are lined with keratinocytes, living cells that move upward, flatten, and eventually become the corneocytes we naturally shed. In a healthy rhythm, sebum flows upward through the follicle and carries these spent cells with it, keeping the passage open and clear.

 

When the skin begins producing more oil than the follicle can comfortably handle, or when the shedding of dead cells becomes irregular or too cohesive, this clearing process slows. The combination of excess sebum and accumulated corneocytes begins to build inside the follicle. Eventually, the narrow opening of the pore becomes crowded and congested. Bacteria accumulates and infection can set in. 

 

It is the skin’s version of a traffic jam. Too much activity inside, not enough exit on the outside.

The Four Root Biological Processes Behind Acne

Acne does not appear for one reason alone. It forms through four interconnected biological processes inside the follicle that together create clogged pores, breakouts, and inflammation.

Excess Sebum Production

Hormones, genetics, and stress can stimulate the sebaceous glands to produce more sebum than the follicle can effectively release. This oil buildup makes the skin more prone to pore congestion and breakouts.

Abnormal shedding of dead skin cells

Inside the follicle, dead keratinocytes should shed in a smooth rhythm. In acne-prone skin, these cells become stickier and accumulate rather than release. This process, known as hyperkeratinization, is the earliest step in forming a clogged pore.

Microbiome imbalance in acne-prone skin

The follicle naturally contains a range of bacteria, including Cutibacterium acnes, which is an essential part of healthy skin. Acne does not develop because there is too much bacteria, but because the balance between strains shifts. There are more than one hundred known variants of C. acnes, grouped into types I, II, and III. Type I strains are more often linked to acne, while types II and III tend to appear in non-acneic skin.

 

When type I strains dominate, the microbiome becomes less diverse and the follicle becomes more reactive. Acne-prone skin often has fewer protective strains, more inflammatory strains, and a stronger immune response to the bacteria present rather than a higher amount overall. Acne is not a bacterial overload, but a shift in the bacterial community and the skin’s response to that shift.

Inflammation

Inflammation is present at every stage of acne, often before a clogged pore becomes visible. It influences how red, swollen, or sensitive a breakout appears and whether it leaves a mark behind. Stress, hormonal changes, UV exposure, harsh skincare, and a disrupted skin barrier can all amplify inflammation and make breakouts more noticeable.

What Causes My Acne

Genetics

Genetics influence how active the sebaceous glands are, how easily dead cells accumulate inside the follicle, our hormones, and how strongly the immune system reacts to congestion. Some people inherit oil glands that produce more sebum, or a follicular lining where cells cling rather than shed. Others inherit a microbiome that is more prone to imbalance or an inflammatory pathway that responds quickly to changes inside the follicle.

Genetics do not guarantee acne, but they create the background conditions where acne forms more readily. 

Lifestyle Triggers

Lifestyle is not the root cause of acne, but it can influence how often breakouts occur or how inflamed they become. The skin responds to everyday patterns such as stress, sleep, environment, friction, and products.

 

Harsh cleansers and aggressive skincare can strip the barrier and disrupt the microbiome, making the skin more reactive. Stress increases cortisol, which can raise androgen activity and stimulate the oil glands. Sleep loss amplifies inflammation and slows repair. Sweat is not harmful on its own, but when combined with friction from clothing, equipment, or accessories, it can clog pores on the back, chest, and hairline.

Heavy makeup, occlusive balms, thick sunscreens, and certain hair oils can migrate into pores and contribute to congestion. Even small habits, like touching your face or pressing your cheek against your phone, can trap heat and bacteria against the skin.

Diet can play a role for some people. High-glycemic foods, sugary drinks, and skim milk may influence oil production and inflammation, although responses vary widely. These factors do not create acne from nothing. They simply tilt an already sensitive follicle toward congestion.

What Causes My Acne

Genetics

Genetics influence how active the sebaceous glands are, how easily dead cells accumulate inside the follicle, our hormones, and how strongly the immune system reacts to congestion. Some people inherit oil glands that produce more sebum, or a follicular lining where cells cling rather than shed. Others inherit a microbiome that is more prone to imbalance or an inflammatory pathway that responds quickly to changes inside the follicle.

Genetics do not guarantee acne, but they create the background conditions where acne forms more readily. 

Lifestyle Triggers

Lifestyle is not the root cause of acne, but it can influence how often breakouts occur or how inflamed they become. The skin responds to everyday patterns such as stress, sleep, environment, friction, and products.

 

Harsh cleansers and aggressive skincare can strip the barrier and disrupt the microbiome, making the skin more reactive. Stress increases cortisol, which can raise androgen activity and stimulate the oil glands. Sleep loss amplifies inflammation and slows repair. Sweat is not harmful on its own, but when combined with friction from clothing, equipment, or accessories, it can clog pores on the back, chest, and hairline.

Heavy makeup, occlusive balms, thick sunscreens, and certain hair oils can migrate into pores and contribute to congestion. Even small habits, like touching your face or pressing your cheek against your phone, can trap heat and bacteria against the skin.

Diet can play a role for some people. High-glycemic foods, sugary drinks, and skim milk may influence oil production and inflammation, although responses vary widely. These factors do not create acne from nothing. They simply tilt an already sensitive follicle toward congestion.

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Microbiome imbalance in acne-prone skin

The follicle naturally hosts a range of bacteria, including Cutibacterium acnes, which is an essential part of healthy skin. Acne does not develop because there is too much bacteria, but because the balance between strains shifts. There are more than one hundred known variants of C. acnes, grouped into three main types: I, II, and III. Type I strains are more often associated with acne, while types II and III tend to appear in non-acneic skin. When type I strains begin to dominate, the equilibrium of the microbiome changes and the follicle becomes more prone to inflammation.

What matters is not the quantity of bacteria but the proportions. In acne-prone skin, certain strains flourish, protective strains decline, and the follicle becomes a low-oxygen environment where inflammatory subtypes thrive. Research shows that people experiencing breakouts often have less microbial diversity, more inflammatory strains, fewer calming or protective strains, and a heightened immune response to the bacteria present rather than a higher number overall.

Lifestyle is not the root cause of acne, but it can influence how often breakouts occur or how inflamed they become. The skin responds to everyday patterns such as stress, sleep, environment, friction, and products.

Hormonal Acne and Why It Appears on the Chin and Jawline

Harsh cleansers and aggressive skincare can strip the barrier and disrupt the microbiome, making the skin more reactive. Stress increases cortisol, which can raise androgen activity and stimulate the oil glands. Sleep loss amplifies inflammation and slows repair. Sweat is not harmful on its own, but when combined with friction from clothing, equipment, or accessories, it can clog pores on the back, chest, and hairline.

 

Heavy makeup, occlusive balms, thick sunscreens, and certain hair oils can migrate into pores and contribute to congestion. Even small habits, like touching your face or pressing your cheek against your phone, can trap heat and bacteria against the skin.

Diet can play a role for some people. High-glycemic foods, sugary drinks, and skim milk may influence oil production and inflammation, although responses vary widely. These factors do not create acne from nothing. They simply tilt an already sensitive follicle toward congestion.

Hormonal Acne and Why It Appears on the Chin and Jawline

Hormones act like the volume dial on your skin’s oil production. When androgens such as testosterone or DHT increase, the sebaceous glands respond quickly with more sebum and faster buildup inside the follicle. This creates the ideal conditions for clogged pores and breakouts.

Hormonal acne often aligns with menstrual cycles, periods of stress, puberty, pregnancy, postpartum shifts, perimenopause, menopause, and PCOS. Because the lower face contains a higher concentration of androgen receptors, the chin, jawline, and lower cheeks are usually the first places hormonal acne appears - but it can appear anywhere. For more information on hormones and skin, read our Hormones page. 

Where Acne Appears and What It Means

Where Acne Appears and What It Means

Chin and jawline

Breakouts in this area are often influenced by hormonal shifts, which increase sebum activity and create deeper, recurring congestion.

Cheeks

Cheek acne often reflects external factors. Microbiome imbalance, makeup, phone contact, pillowcases, and touching your skin with your hands can disrupt this area, especially where sebum production is lower and the barrier is more reactive.

Forehead

Forehead breakouts can follow stress, poor sleep, or the migration of haircare products. Sweat and sebum can mix easily along the hairline, creating quick congestion.

Back and chest

These areas respond strongly to occlusion and heat. Sweat, sebum, tight fabrics, and sports gear can trap buildup against the skin, leading to clogged pores on the body.

Treatments That Work for Acne-Prone Skin

Treatments That Work for Acne-Prone Skin

A blend of skincare actives, OTC drugs, prescription options, and in-office laser treatments.

Retinoids

Retinoids help keep pores clear by supporting natural shedding. They refine texture, reduce the look of visible redness, and create a smoother appearance.

Salicylic acid

An oil-soluble OTC acne ingredient that helps sweep away buildup inside the follicle and clears up blackheads and pimples.

Azelaic acid

Helps visibly reduce the look of surface redness, soften the look of post-blemish marks, and calm the appearance of irritation. Suitable for sensitive or reactive skin.

Niacinamide

Supports the skin barrier, balances oil, calms the look of visible redness, and enhances skin resilience.

Microbiome-balancing ingredients

Fermented ingredients help support a balanced-looking microbiome by providing bioactive compounds that soothe the skin, reinforce barrier harmony, and encourage a diverse, more resilient microbial environment.

Zinc PCA and zinc gluconate

Help balance excess oil, reducing the look and feel of shiny skin.

Lactic acid and other AHAs

AHAs complement acne care by brightening and refining the surface of the skin.

Moisturizers for acne-prone skin

Hydration supports a healthy barrier and prevents the rebound effect commonly seen in stripping or drying out oily skin (which can cause a rebound of excess oil production). Lightweight, water-based formulas are best.

Prescription options

Dermatologists may recommend prescription antibiotics, retinoids, or hormonal medications, like birth control, when necessary.

In-office acne treatments

Dermatology offices offer light-based and laser treatments that can improve the look of lingering redness, uneven tone, and visible texture changes. Blue light, VBeam, and IPL can help soften visible redness, while fractional lasers such as Fraxel, Clear + Brilliant, or Halo refine texture and post-blemish marks. Photodynamic therapy uses a light-activated solution for skin that looks persistently congested. More intensive CO₂ or erbium lasers may be used for deeper irregularities.

What to Avoid if You Have Acne

Some habits can make acne more noticeable. Avoid harsh scrubs, reusing washcloths, infrequent pillowcase changes, over-washing, stripping the barrier, heavy occlusives, and picking or squeezing. Acne improves when the skin is supported rather than stressed.

Morning Skincare Routine for Acne-Prone Skin 

Evening Skincare Routine for Acne-Prone Skin 

Acne FAQ

What causes acne?

Acne forms through excess oil, dead skin cell buildup, microbiome imbalance, and inflammation inside the pore. Hormones, genetics, and lifestyle patterns can intensify these processes.

Why am I breaking out?

Breakouts can appear due to hormonal shifts, increased oil, clogged pores, stress, disrupted sleep, or heavy products. A weakened barrier or unbalanced microbiome can also make the skin more reactive.

What is the best skincare routine for acne?

In our opinion, a good routine includes a gentle cleanser, niacinamide, salicylic acid or azelaic acid, lightweight hydration, and sunscreen in the morning. At night, cleanse, support the microbiome, use a retinoid, and finish with a light moisturizer.

Which Sunday Riley cleanser is best for acne?

Breakout Breakup Cleanser is designed for acne-prone skin. It removes oil, buildup, sunscreen, and makeup without stripping the barrier.

Do I need to double cleanse?

No. Breakout Breakup Cleanser is formulated to remove sunscreen and daily impurities in a single cleanse.

What should I use after cleansing?

Follow cleansing with Detox Darling Pro-Microbiome Balancing Essence to support the microbiome and help curb excess oil.

Do moisturizers make acne worse?

Lightweight moisturizers like Tidal Deep Hydration + Plumpling Serum or UFO Ultra Clarifying Face Oil help maintain barrier health and gently moisturize the skin.

How do I fade acne dark spots?

Use retinoids, azelaic acid, AHAs like lactic acid, vitamin C, and daily sunscreen. These help improve the appearance of post-acne marks over time.

What is fungal acne?

Fungal acne, or Malassezia folliculitis, is an overgrowth of yeast rather than bacteria. It appears as small, uniform bumps that worsen with sweat or humidity and responds best to antifungal care.

How do hormones cause acne?

Increases in androgens raise oil production and speed up buildup inside the pore. This often leads to clogged pores and breakouts along the chin and jawline.

When should I see a dermatologist?

If you would like an expert medical opinion, or experience cystic acne, nodules, scarring, frequent breakouts, or acne that does not improve with consistent routine care, a dermatologist can offer prescription options and/or in-office treatments.

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Disclaimer:
This information is for general educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider or dermatologist with any questions about your skin or a medical condition, and seek professional care if your symptoms persist or worsen.