Acne is a common inflammatory skin condition that affects the hair follicles and sebaceous glands, primarily during adolescence, though it can persist into adulthood. It typically appears on the face, chest, shoulders, and back and can cause both physical discomfort and emotional distress.
Causes
Acne is caused by several factors acting together:
- Increased production of sebum (an oily substance) by the sebaceous glands
- Blockage of hair follicles by dead skin cells and sebum
- Proliferation of Cutibacterium acnes (formerly Propionibacterium acnes) bacteria within follicles
- Inflammation triggered by bacterial overgrowth and blocked follicles
- Hormonal changes, especially androgens, play a major role in increasing sebum production.
Pathophysiology
Acne begins when the opening of a hair follicle becomes blocked. Excess sebum and dead skin cells accumulate, forming comedones (whiteheads or blackheads). If bacteria such as Cutibacterium acnes are present, they multiply within the blocked follicle, leading to inflammation. This results in papules, pustules, nodules, or cysts depending on severity.
Signs and Symptoms
- Non-inflammatory lesions: open comedones (blackheads), closed comedones (whiteheads)
- Inflammatory lesions: red papules, pustules (pus-filled spots), nodules, cysts
- Pain or tenderness in nodulocystic acne
- Skin hyperpigmentation or scarring in severe or untreated cases
Risk Factors
- Adolescence and puberty
- Hormonal changes (e.g., menstruation, pregnancy, polycystic ovary syndrome)
- Use of certain cosmetics or oily products
- Family history of acne
- Medications (e.g., corticosteroids, lithium, androgens)
- Emotional stress
- Poor skincare routines or excessive skin washing
Investigations
In most cases, acne is diagnosed clinically based on appearance and distribution. However, further investigation may be required in specific circumstances:
- Hormonal testing (e.g., testosterone, LH, FSH) in suspected PCOS or endocrine abnormalities
- Bacterial culture in resistant or recurrent cases to check for antibiotic resistance
- Ultrasound or imaging if underlying PCOS is suspected in women
- Routine imaging is not usually needed unless another diagnosis is being considered.
Management
1. Non-Pharmacological
- Gentle skin cleansing with mild, non-comedogenic products
- Avoid picking or squeezing lesions to reduce scarring
- Use of oil-free cosmetics and sunscreens
- Healthy diet and hydration: While evidence is mixed, a low glycaemic index diet may help
- Psychosocial support for individuals experiencing distress due to acne
2. Pharmacological
NICE recommends a stepwise approach based on severity:
- Mild acne: Topical retinoids (e.g., adapalene), benzoyl peroxide, or azelaic acid
- Moderate acne: Combination of topical agents plus oral antibiotics (e.g., doxycycline, lymecycline) for a maximum of 3 months
- Severe acne or scarring: Referral to dermatology for oral isotretinoin, a powerful vitamin A derivative (requires careful monitoring due to teratogenicity and mental health risks)
- Hormonal treatments: Co-cyprindiol for women with moderate to severe acne, particularly if associated with PCOS
3. Surgical/Procedural
- Comedone extraction: Performed by dermatologists for persistent comedones
- Intralesional steroid injections: For large nodules or cysts
- Laser and light therapies: Limited evidence but may help in selected cases
- Chemical peels or microdermabrasion: Cosmetic procedures for post-acne scarring
Complications
- Post-inflammatory hyperpigmentation
- Permanent scarring (atrophic or hypertrophic)
- Psychological impact: Depression, anxiety, social withdrawal, and low self-esteem
- Antibiotic resistance: Due to long-term or inappropriate antibiotic use
- Isotretinoin side effects: Dry skin, teratogenicity, mood changes
References
- NICE Clinical Guidelines: Acne vulgaris: management (NG198, published 2021)
- British Association of Dermatologists: Acne treatment pathways
- Royal College of General Practitioners: Dermatology module
- General Medical Council (GMC): Good Clinical Practice standards
- NHS: Acne overview and management strategies