Acne Severity Classification (IGA Scale)
Classifies acne vulgaris severity using the Investigator Global Assessment (IGA) scale. Guides topical vs systemic vs isotretinoin prescribing.
Score interpretation
→ Topical benzoyl peroxide, adapalene, or azelaic acid; skincare advice; review in 12 weeks; no antibiotic monotherapy
→ Combined oral antibiotic (doxycycline/lymecycline) + topical retinoid + BPO (max 3 months); consider combined oral contraceptive in females; dermatology referral if no response
→ Urgent dermatology referral; oral isotretinoin (0.5-1mg/kg/day) — pregnancy prevention programme for females; baseline lipids, LFTs, FBC; monthly monitoring; stop oral antibiotics before starting isotretinoin
Interpretation bands for the Acne Severity. Apply clinical judgement and local guidance.
References
Related
Curated clinical cross-links plus same-class fallbacks.
- Isotretinoin · Systemic retinoid (Vitamin A derivative) / Anti-acne
- Methotrexate (Dermatology — Psoriasis) · Disease-Modifying Antirheumatic / Immunosuppressant
- Doxycycline 100mg (Acne / Rosacea) · Oral tetracycline antibiotic (anti-acne / anti-rosacea)
- Lymecycline 408mg (Acne) · Oral tetracycline antibiotic (anti-acne)
- Erythromycin 2% Topical · Topical macrolide antibiotic (anti-acne)
- Adapalene 0.1% Topical · Topical retinoid (anti-acne)
- Suspicious Pigmented Lesion — Melanoma Pathway · NICE NG14 2015 / BAD
- Cellulitis and Erysipelas · NICE NG141 2019 / CREST
- Psoriasis — Severity Assessment and Step-Up Therapy · NICE NG153 2019 / BAD
- Atopic Eczema — Assessment and Step-Up Therapy · NICE NG95 2023
- Urticaria and Angioedema · BSACI / EAACI Guidelines 2022
- Acne Vulgaris — Grading and Treatment · NICE NG198 2021 / BAD
Decision support only — verify against a current formulary, NICE, or your local guideline before clinical use.