Classification of Topical Corticosteroid Potency for Treating Skin Conditions
Topical corticosteroids are classified into 7 classes based on potency, with Class I being the most potent (superpotent) and Class VII being the least potent (very mild). 1
Standard Potency Classification System
Class I (Superpotent)
- Clobetasol propionate 0.05% (cream, ointment, foam, solution)
- Halobetasol propionate 0.05% (cream, ointment)
- Betamethasone dipropionate 0.05% (optimized vehicle)
Class II (Potent)
- Desoximetasone 0.25% (cream, ointment)
- Fluocinonide 0.05% (cream, ointment, gel)
- Halcinonide 0.1% (cream, solution)
Class III (Upper Mid-Strength)
- Fluticasone propionate 0.005% (ointment)
- Triamcinolone acetonide 0.5% (cream, ointment)
- Betamethasone valerate 0.1% (ointment)
Class IV (Mid-Strength)
- Betamethasone valerate 0.1% (cream, foam)
- Fluocinolone acetonide 0.025% (cream, ointment)
- Triamcinolone acetonide 0.1% (cream, ointment)
Class V (Lower Mid-Strength)
- Hydrocortisone butyrate 0.1% (cream)
- Fluticasone propionate 0.05% (cream)
- Hydrocortisone valerate 0.2% (cream)
Class VI (Mild)
- Desonide 0.05% (cream, lotion)
- Fluocinolone acetonide 0.01% (oil, solution)
- Alclometasone dipropionate 0.05% (cream, ointment)
Class VII (Very Mild)
- Hydrocortisone 1%, 2.5% (cream, ointment, lotion)
- Dexamethasone 0.1% (cream)
Clinical Considerations for Potency Selection
Anatomical Site Considerations
When selecting topical corticosteroid potency, consider the anatomical site of application:
- Face, neck, genitals, and body folds: Use lower potency agents (classes V-VII) due to increased risk of skin atrophy 1
- Trunk and extremities: Medium potency (classes III-IV) can be used for longer courses 1
- Thick, lichenified areas: Higher potency agents (classes I-II) may be needed for short courses 1
Efficacy Based on Potency
Efficacy rates vary by potency class:
- Class I (superpotent): 58%-92% improvement
- Class II (potent): 68%-74% improvement
- Classes III-IV (midstrength): 68%-72% improvement
- Classes V-VII (lower potency): 41%-83% improvement 1
Duration of Use Based on Potency
- Class I (superpotent): Limit to 2-4 weeks of continuous use 1
- Classes II-IV (potent to midstrength): Can be used for up to 12 weeks 2
- Classes V-VII (lower potency): No specified time limit for low-potency agents 2
Common Pitfalls and Caveats
Patient Understanding of Potency
- Only 17% of patients/caregivers know how many potency levels exist for topical corticosteroids 3
- 31% of patients misclassify hydrocortisone (mild) as strong or very strong 4
- 72.5% of patients worry about using topical corticosteroids, with 24% admitting to non-compliance due to these concerns 4
Avoiding Adverse Effects
Risk of adverse effects (skin thinning, striae, telangiectasias) increases with:
- Higher potency
- Prolonged use
- Occlusion
- Application to thin-skinned areas
- Large surface area application 2
For children, use lower potencies and shorter durations 2
For localized mild disease, very potent topical steroids applied to lesional skin only can be effective 1
Inconsistency Between Classification Systems
Be aware that different classification systems exist:
- US system (7 categories)
- UK/Cochrane system (4 categories)
- ATC system (4 categories)
These systems show only moderate agreement but strong correlation between them, which may lead to confusion in clinical practice 5.
Application Guidelines
- One fingertip unit (amount from fingertip to first crease) covers approximately 2% body surface area 2
- Apply once or twice daily for best results 6
- For maintenance therapy to prevent flares, consider weekend therapy (twice weekly application) which reduces relapse rates from 58% to 25% 6
By understanding the potency classification of topical corticosteroids and applying appropriate agents based on anatomical location and disease severity, clinicians can optimize efficacy while minimizing adverse effects in treating skin conditions like eczema.