Acne (Pimples): Causes, Pathophysiology, and Evidence-Based Management

Pathogenesis of Acne Vulgaris

Acne is a chronic inflammatory disease of the pilosebaceous unit driven by four key factors:

1. Excess sebum production (androgen-driven)
2. Follicular hyperkeratinization (abnormal desquamation → microcomedone)
3. Cutibacterium acnes (formerly P. acnes) proliferation
4. Inflammation (innate and adaptive immune response)

Contributing Factors

Factor	Mechanism	Evidence
Hormonal	Androgens ↑ sebum; menstrual cycle flares; PCOS	Strong
Genetics	Heritability ~80%; multiple loci identified	Strong
Diet	High glycemic load, dairy (especially skim milk) ↑ IGF-1 → sebum/inflammation	Moderate (observational)
Stress	CRH, cortisol → sebocyte activation; neuropeptides	Moderate
Medications	Corticosteroids, lithium, androgens, EGFR inhibitors, some OCs	Well-established
Cosmetics	Comedogenic products (occlusive oils, butters)	Variable
Mechanical	Friction, pressure (helmets, straps, picking)	Acne mechanica

Treatment by Severity (Guideline-Based)

Mild (Comedonal / Few Papulopustules)

• Topical retinoid (adapalene 0.1/0.3%, tretinoin 0.025–0.05%) – cornerstone; prevents microcomedones.
• Benzoyl peroxide (BPO) 2.5–5% – bactericidal, anti-inflammatory, prevents resistance.
• Combination (adapalene/BPO, clindamycin/BPO) – superior to monotherapy.

Moderate (Many Papulopustules, Some Nodules)

• Topical retinoid + BPO ± topical antibiotic (clindamycin, erythromycin) – limit antibiotic monotherapy (resistance).
• Oral antibiotics (doxycycline, minocycline, sarecycline) 3–6 months + topical retinoid/BPO.
• Hormonal therapy (females): Combined OCs (EE/drospirenone, norgestimate), spironolactone 50–100 mg/day.

Severe (Nodulocystic, Scarring, Psychosocial Impact)

• Oral isotretinoin: Only curative therapy; 0.5–1 mg/kg/day × 4–6 months (cumulative 120–150 mg/kg). Requires iPLEDGE (US), pregnancy prevention, lipid/LFT monitoring.
• Early referral to dermatologist essential.

Adjunctive / Procedural

• Intralesional Kenalog (triamcinolone) for large nodules.
• Chemical peels (salicylic, glycolic), laser/light therapy – adjunctive.
• Extraction (comedones) by professional.

Maintenance

After clearance: continue topical retinoid ± BPO long-term to prevent recurrence.

See a dermatologist for personalized regimen, especially if scarring, pigmentary changes, or quality-of-life impact.