Easy Guide to Topical Corticosteroid Potencies
Topical corticosteroids are classified into 7 categories based on their skin vasoconstrictive activity, ranging in strength from ultra-high (class 1) to low (class 7), with class 1 being the most potent and classes 6-7 being the least potent. 1
Potency Classification System
| Class | Potency Level | Efficacy Range | Examples |
|---|---|---|---|
| 1 | Ultra-high/Superpotent | 58%-92% | Clobetasol propionate, Halobetasol propionate |
| 2 | High/Potent | 68%-74% | Betamethasone dipropionate, Fluocinonide |
| 3-4 | Medium/Mid-strength | 68%-72% | Triamcinolone acetonide, Fluticasone propionate |
| 5-7 | Low/Mild | 41%-83% | Hydrocortisone 1%, Desonide 0.05% |
Selection Guidelines
- For thick, chronic plaques: Class 1 (ultra-high potency) corticosteroids 1
- For moderate to severe plaque psoriasis: Class 2-5 (moderate to high potency) corticosteroids 1
- For sensitive areas (face, intertriginous areas, genitals):
- For children: Lower potency and shorter duration; consider alternatives like calcineurin inhibitors for prolonged facial use 2
Formulation Selection
- Ointments: Best for dry, lichenified lesions; provide occlusion for maximum penetration 2
- Creams: Suitable for weeping/oozing lesions, intertriginous areas, and when cosmetic acceptability is important 2
- Lotions/Solutions: Preferred for hairy areas like the scalp 2
Application Guidelines
- Apply using the "fingertip unit" method: amount that covers from the tip of the index finger to the first crease of the distal interphalangeal joint 2, 3
- One fingertip unit covers approximately 2% of body surface area in an adult 2, 3
- Apply once or twice daily for:
- Up to 3 weeks for super-high-potency corticosteroids
- Up to 12 weeks for high or medium-potency corticosteroids
- No specified time limit for low-potency topical corticosteroids 3
Duration of Treatment
- For class 1-5 corticosteroids: Use for up to 4 weeks for plaque psoriasis not involving intertriginous areas 1
- For long-term use (>12 weeks): Only under careful physician supervision 1
- Consider proactive maintenance therapy with twice-weekly application of low to medium potency TCS to prevent relapses 2
Common Pitfalls to Avoid
- Steroid phobia: Advising patients to apply "sparingly" may lead to undertreatment and poor clinical response 4
- Prolonged use on sensitive areas: Can lead to skin atrophy, telangiectasia, striae, and steroid-induced rosacea 2
- Inappropriate potency selection: Using high-potency steroids on thin skin areas or low-potency on thick plaques 1
- Occlusion without supervision: Substantially increases percutaneous absorption 5, 6
- Application on infected skin: Should be avoided without concurrent antibiotic treatment 2
Special Considerations
- Approximately 400g of topical agent is required to cover the entire body surface of an average-sized adult when used twice daily for 1 week 1
- For patients requiring continuous topical treatment, use the least potent agent that allows for disease control 1
- Consider topical calcineurin inhibitors as steroid-sparing alternatives for sensitive areas or when prolonged treatment is needed 2
This classification system provides a structured approach to selecting the appropriate topical corticosteroid based on potency, anatomical location, and patient characteristics.