Acne is caused primarily when hair follicles (tiny holes in the skin where hairs grow) become clogged with a combination of excess oil (sebum) produced by sebaceous glands and dead skin cells. This clogging creates plugs called comedones, which can either be closed (whiteheads) or open (blackheads). The main factors that contribute to acne development include:
- Excess oil (sebum) production by sebaceous glands
- Hair follicles clogged by oil and dead skin cells
- Bacterial growth, especially by the normally harmless skin bacteria Propionibacterium acnes (C. acnes), which can infect clogged follicles and cause inflammation
- Inflammation of the clogged follicles
Acne commonly appears on areas with more sebaceous glands, such as the face, forehead, chest, upper back, and shoulders. Hormonal changes are a major trigger for increased sebum production and acne formation, particularly during puberty due to increased androgens (e.g., testosterone). Hormonal fluctuations during menstrual cycles, pregnancy, or conditions like polycystic ovary syndrome (PCOS) can also worsen acne. Other factors that may trigger or worsen acne include certain medications (like corticosteroids, testosterone, lithium), some cosmetic products, diet (particularly high glycemic index foods and dairy for some people), stress (which can exacerbate existing acne), heavy sweating, and friction or irritation from touching or rubbing the skin. Acne is also influenced by genetics, with a strong hereditary component observed. In summary, acne results from a combination of excess oil production, clogged hair follicles with dead skin cells, bacterial infection, and inflammation, often triggered or worsened by hormonal changes and other factors like medications, diet, and stress. This explanation integrates information from sources such as Mayo Clinic, Penn Medicine, NHS, Healthline, and Wikipedia that detail the causes and contributing factors of acne.
