What causes acne

Overview of Acne

Acne is a common skin condition affecting over 85% of people between ages 12 and 24. It results from a complex interplay of four main factors: increased oil production, clogged pores, bacterial colonization, and inflammation. These factors combine to create comedones (blackheads and whiteheads) and inflammatory lesions (pimples and nodules). Understanding these causes helps explain why acne develops and how different treatments address different aspects of the condition.

Hormonal Influences

Hormones, particularly androgens, play a central role in acne development. During puberty, hormone levels surge, stimulating the sebaceous glands to produce more sebum (oil). This hormonal influence explains why acne typically begins during adolescence. Women may experience acne flares during menstrual cycles, pregnancy, and menopause due to hormonal fluctuations. Conditions affecting hormone levels, such as polycystic ovary syndrome (PCOS), can trigger or worsen acne significantly.

Excess Oil and Clogged Pores

Sebaceous glands produce sebum to protect and lubricate skin. However, in acne-prone individuals, these glands produce excess oil. Simultaneously, dead skin cells accumulate and fail to shed properly. When dead skin cells mix with excess sebum, they can block hair follicles and pores. This combination creates an ideal environment for acne development. The blocked pores trap oil and bacteria inside, forming comedones that can be seen on the skin's surface.

Bacterial Colonization

The bacterium Cutibacterium acnes (formerly called Propionibacterium acnes) naturally inhabits skin and is part of normal skin flora. However, within blocked pores, this bacterium proliferates rapidly. The bacteria produce substances that trigger the immune system to attack, causing inflammation. Additionally, these bacteria produce fatty acids that further irritate the skin. This bacterial colonization is why antibiotics and antimicrobial treatments can help control acne, though antibiotic resistance is becoming an increasing concern.

Genetic Predisposition

Acne shows strong genetic components. Children of parents with acne history are more likely to develop acne themselves. Genetics influence sebum production, skin cell turnover rate, and immune response to bacterial colonization. If both parents experienced acne, children have approximately an 80% chance of developing it. This genetic predisposition explains why some people develop severe acne while others remain unaffected despite similar environmental factors.

Contributing Dietary and Environmental Factors

While not primary causes, several factors can worsen acne in susceptible individuals. High-glycemic foods and dairy products may trigger acne flares in some people. Environmental factors including high humidity, pollution, and friction from tight clothing can exacerbate acne. Certain cosmetics and skin care products can clog pores. Stress triggers hormonal changes that increase sebum production. Recognizing these secondary factors helps people manage acne more effectively through lifestyle modifications.