Topical Corticosteroid Potency Classification
Topical corticosteroids are classified into 7 categories based on their skin vasoconstrictive activity, ranging from ultra-high potency (class 1) to low potency (classes 6-7), with class 1 being the most potent and classes 6-7 being the least potent. 1
Potency Classification System
| Class | Potency Level | Examples | Relative Potency | Appropriate Use |
|---|---|---|---|---|
| 1 | Ultra-high/Superpotent | Clobetasol propionate 0.05%, Halobetasol propionate 0.05% | 600-1000× hydrocortisone | Thick, hyperkeratotic lesions; limited to 2-4 weeks |
| 2 | High/Potent | Betamethasone dipropionate 0.05%, Fluocinonide 0.05% | 100-500× hydrocortisone | Moderate-severe dermatoses; trunk and extremities |
| 3-4 | Medium/Mid-strength | Triamcinolone acetonide 0.1%, Fluticasone propionate 0.05% | 10-100× hydrocortisone | Moderate dermatoses; trunk and extremities |
| 5-7 | Low/Mild | Hydrocortisone 1-2.5%, Desonide 0.05%, Alclometasone 0.05% | 1-10× hydrocortisone | Face, intertriginous areas, children |
Efficacy Range by Potency Class
- Class 1 (Ultra-high): 58%-92% efficacy
- Class 2-3 (High-Medium): 68%-74% efficacy
- Class 4-7 (Medium-Low): 41%-83% efficacy 1
Anatomical Considerations for Potency Selection
Face, groin, axillae: Use Class 5-7 (low potency) steroids only
Trunk and extremities: Can use Class 1-4 depending on severity
- Higher potency steroids are appropriate for thicker skin areas
Intertriginous areas: Use Class 5-7 (low potency) only
- Increased absorption in these areas increases risk of side effects
Vehicle Selection Based on Condition
- Creams: Preferred for weeping/oozing lesions, intertriginous areas, and when cosmetic acceptability is important 1
- Ointments: Preferred for dry, lichenified lesions; more occlusive and generally more potent
- Lotions/Solutions: Preferred for hairy areas like the scalp 1
Duration of Use Guidelines
- Class 1-2 (Ultra-high/High potency): Limit to 2-4 weeks of continuous use
- Class 3-5 (Medium potency): Limit to up to 12 weeks of continuous use
- Class 6-7 (Low potency): No specific time limit, but regular monitoring is still recommended 2
Safety Precautions
- Monitor for signs of skin atrophy, telangiectasias, striae, or steroid-induced rosacea 1
- Systemic absorption can occur with high-potency steroids, especially when:
- Applied to large surface areas
- Used with occlusive dressings
- Used for prolonged periods 3
- Clobetasol propionate has been shown to suppress the HPA axis at doses as low as 2g per day 3
Special Populations
Children: Use the lowest effective potency and shortest duration possible
Pregnant/Lactating patients: Topical corticosteroids can work safely and effectively with appropriate monitoring 2
Application Technique
- Use the "fingertip unit" method: amount that covers from the tip of the index finger to the first crease of the finger
- One fingertip unit covers approximately 2% of body surface area in an adult 1, 2
Common Pitfalls and Caveats
Potency labeling confusion: Studies show only 17% of patients know how many potency levels exist, and 45% incorrectly identify the potency of their prescribed steroid 4
Inappropriate use on sensitive areas: Never use ultra-high potency steroids on the face, groin, or axillae due to increased risk of atrophy, striae, and other adverse effects 1, 3
Duration errors: Using high-potency steroids for too long can lead to tachyphylaxis (decreased effectiveness) and increased risk of side effects 2
Steroid phobia: Underdosing due to fear of side effects can lead to treatment failure; proper education on appropriate use is essential 4
By understanding the potency classification of topical corticosteroids and following appropriate guidelines for their use, clinicians can maximize therapeutic benefits while minimizing adverse effects.