Acne vulgaris

Overview

•Affects face, upper chest, upper back (highest density of pilosebaceous units)

•Comedones - open (blackheads) or closed (whiteheads); non-inflammatory; presence of comedones distinguishes acne vulgaris from rosacea

•Papules - small (<5mm), raised, red inflammatory lesions

•Pustules - papules containing visible pus

•Nodules - larger (>5mm), deeper, firmer; extend into dermis; more likely to scar

•Cysts - fluctuant, deep, pus-filled; most severe; prone to rupture and scarring

•Always assess psychosocial impact - anxiety, depression, school/work attendance

Differential diagnosis

Key differentials
FeatureAcne vulgarisAcne rosaceaImpetigo
ComedonesYes - key featureNo comedonesNo comedones
AgeAdolescents/young adultsAdults 30-50+School-aged children
Key featuresComedones, papules, pustules, nodulesErythema, flushing, telangiectasia, papulopustulesHoney-coloured crusts around mouth

Feature	Acne vulgaris	Acne rosacea	Impetigo
Comedones	Yes - key feature	No comedones	No comedones
Age	Adolescents/young adults	Adults 30-50+	School-aged children
Key features	Comedones, papules, pustules, nodules	Erythema, flushing, telangiectasia, papulopustules	Honey-coloured crusts around mouth

Management

•Treatments take 6-8 weeks to show effect; full course is 12 weeks before escalating

•First-line (mild-moderate) - topical combination:

•Adapalene 0.1%/0.3% + benzoyl peroxide 2.5% - once daily in the evening (preferred)

•Tretinoin 0.025% + clindamycin 1% - alternative retinoid + antibiotic combination

•Benzoyl peroxide 3%/5% + clindamycin 1% - if retinoid not tolerated

•Second-line (moderate-severe) - add oral antibiotic:

•Doxycycline 100mg OD for maximum 3 months (lymecycline 408mg OD is an alternative) - combined with topical non-antibiotic agent; do not exceed 100mg OD

•COCP (e.g. co-cyprindiol) - alternative to oral antibiotics in females only; contraindicated in migraine with aura (UKMEC4)

•Third-line (severe/treatment failure) - secondary care only:

•Isotretinoin (oral) - prescribed and monitored by specialist dermatologist only; Pregnancy Prevention Programme required (highly teratogenic); side effects include dry skin/lips/eyes, elevated triglycerides, mood changes, suicidal ideation

⚠️
Never prescribe topical and oral antibiotics together - no additional benefit and drives antibiotic resistance. Always pair an oral antibiotic with a topical non-antibiotic agent (BPO or retinoid).

Referral to dermatology

•Mild-moderate acne not responding to two completed treatment courses

•Moderate-severe acne not responding to a course that includes an oral antibiotic

•Acne with scarring

•Acne with persistent pigmentary changes

•Acne (any severity) causing persistent psychological distress or a mental health disorder

🎯
Isotretinoin cannot be initiated in primary care - refer to dermatology first. If a patient has failed oral antibiotics and has scarring or severe disease, the correct answer is referral to dermatology, not prescribing isotretinoin yourself.