Why does acne occur?

What happens inside a blocked pore?

A hair follicle is a small tube in the skin that holds a hair. Oil glands empty into follicles, producing sebum, the oil that helps protect your skin. Dead skin cells normally shed, but they can get stuck inside a follicle. When enough material builds up, a plug forms. Inflammation around the blockage causes swelling, pain and changes in skin colour.4

The resulting spots can take several forms:

• Blackheads and whiteheads are blocked pores without obvious inflammation.
• Papules are raised bumps; pustules are raised bumps containing pus.
• Nodules and cysts are deeper lumps that can be painful and leave scars.

Why do hormones and family history matter?

During puberty, hormones called androgens enlarge the skin's oil glands and increase oil production. That extra oil can clog pores, which helps explain why acne is so common in teenagers. Hormonal changes around periods, pregnancy and menopause can also contribute to breakouts.15

Acne can begin in adulthood, continue from the teenage years or return after years without breakouts. A parent or close blood relative with deep, painful acne increases your risk of developing that type. Family history raises the risk; it cannot predict exactly how severe your acne will become.5

What can trigger or worsen breakouts?

Oily skincare, makeup and hair products can worsen acne. Skincare and hair products both belong on the checklist, even if the bottles live in separate departments. Tight clothing and sports headgear can also contribute, as can high humidity. Some medicines, including steroids and certain hormone treatments, can provoke breakouts.245

Stress does not cause acne by itself, but it can worsen existing acne. Too little sleep can also make breakouts worse. These are possible aggravating factors, not reasons to blame yourself for having acne.35

Food is not a universal explanation. Chocolate and greasy foods are often blamed, but there is little evidence that food has a large effect on acne for most people. Some studies link acne with skim milk, whey protein and diets high in sugar; diets high in dairy and high glycaemic foods can provoke flares. Those links do not make every breakout a reason to ban the same foods.234

Where does hormonal acne occur?

Hormonal acne often appears on the cheeks, but it can also affect other parts of the face, neck, back, shoulders and chest. It develops when hormonal changes increase oil production, which contributes to clogged pores. Hormonal acne affects both men and women, although it is more common in women. Breakouts around periods, after stopping birth control, during pregnancy or during menopause are useful details to discuss with a clinician.6

Why does acne occur on the chin?

Chin acne follows the same general process as acne elsewhere on the face: follicles become blocked and can become inflamed. Location alone is not enough to identify a hormonal cause. A clinician also considers your cycle, medicines, products and other changes in your health. Breakouts around the mouth can sometimes be perioral dermatitis rather than acne, which requires a different treatment approach.167

Why does acne occur on the back?

The upper back is a common acne site because it has many oil glands. The same oil, dead skin cells and inflammation involved in facial acne can affect back follicles. Tight clothing can contribute to breakouts. Wear loose, breathable clothing, especially while exercising or sweating, and avoid scrubbing or squeezing back spots.14

Why does acne occur on the chest?

The chest also has many oil glands, making it another common place for blocked follicles and acne. Hormonal acne can affect the chest too. Chest breakouts are not automatically acne: folliculitis, an inflammation or infection involving hair follicles, can look similar. Persistent or worsening bumps deserve an examination rather than repeated changes of acne products.467

What should you do about acne?

• Wash gently twice a day with a gentle cleanser. Do not scrub.
• Remove makeup at the end of the day.
• Choose skincare and makeup labelled noncomedogenic, meaning formulated not to clog pores.
• Ask a pharmacist about a suitable acne treatment, such as benzoyl peroxide or salicylic acid, and follow its directions.
• Avoid picking or squeezing spots, which can cause scars.

A noncomedogenic label helps you choose products, not assemble the entire matching shelf. Check hair products as well as products applied directly to your face.15

Treatments address different parts of the process. Benzoyl peroxide reduces bacteria; salicylic acid helps prevent follicles from clogging; retinoids clear blocked pores. Lower concentrations of benzoyl peroxide and wash formulations are less irritating. Retinoids are generally applied across the affected area rather than only to individual spots, to help prevent new breakouts.47

Prescription retinoids are often used in the evening. Follow your prescriber's instructions and protect exposed skin with broad spectrum, water resistant sunscreen of SPF 30 or higher. If irritation develops, discuss changes to the amount, frequency or moisturizer order with your dermatologist rather than changing a prescribed routine yourself. Topical antibiotics are used with benzoyl peroxide to reduce antibiotic resistance, where bacteria stop responding to treatment.7

During pregnancy, ask your healthcare provider to choose a suitable acne treatment before starting one. Topical retinoids and isotretinoin should be avoided during pregnancy.6

How long does treatment take?

Plan on at least 6 to 8 weeks before seeing fewer breakouts, with some retinoid treatments taking several months to show results. Acne treatment works over weeks, a less convenient schedule than the skincare aisle's enthusiasm suggests. Applying more prescription combination medication than directed will not clear acne faster and can increase unwanted effects such as dryness, peeling and burning.47

When should you see a doctor?

See a doctor if treatment is not helping, you have many spots, deep painful lumps or scarring, or acne is affecting your mental health. Hot, swollen skin with redness can signal infection; redness can be harder to see on brown and black skin. Sudden, severe adult breakouts can also warrant checks for an underlying condition. Seek urgent assessment if severe acne comes with fever, joint or bone pain, or ulcerated skin lesions.124