Topical Corticosteroid Classification by Potency
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, 2
Complete Classification System
Class 1 (Ultra-high/Superpotent)
Class 2 (High/Potent)
Class 3-4 (Medium/Mid-strength)
- Triamcinolone acetonide 0.1%
- Fluticasone propionate 0.05%
- Mometasone furoate 0.1%
- Prednicarbate 0.1% 3
- Efficacy range: 68%-72% 1, 2
Class 5-7 (Low/Mild)
- Hydrocortisone 1% and 2.5%
- Desonide 0.05%
- Alclometasone dipropionate 0.05%
- Fluocinolone acetonide 0.01%
- Efficacy range: 41%-83% 1, 2
Clinical Application Based on Potency
Appropriate Use by Anatomical Location
- Class 1 (Ultra-high potency): Use for thick, chronic plaques on glabrous skin, palms, and soles 1
- Class 2-5 (Moderate to high potency): Recommended as initial therapy for most adult plaque psoriasis not involving sensitive areas 1
- Class 5-7 (Low potency): Appropriate for face, intertriginous areas, genitals, and areas susceptible to steroid atrophy 1, 2
Duration of Treatment
- For class 1-5 corticosteroids: Use for up to 4 weeks for plaque psoriasis 1
- For long-term use (>12 weeks): Only under careful physician supervision 1
Formulation Considerations
- Creams: Preferred for weeping or oozing lesions, intertriginous areas, and when cosmetic acceptability is important 2
- Ointments: Preferred for dry, lichenified lesions 2
- Lotions/Solutions: Preferred for hairy areas like the scalp 2
Potential Risks and Monitoring
- Common local adverse effects include skin atrophy, striae, folliculitis, telangiectasia, and steroid-induced acne or rosacea 1, 2
- Higher potency steroids carry greater risk of HPA axis suppression when used over large surface areas or under occlusion 3
- Monitor for signs of cutaneous atrophy, telangiectasias, striae, or steroid-induced rosacea with prolonged use 2
Special Considerations
- For children: Use lowest potency and shortest duration possible due to their larger skin surface area to body mass ratios 3
- 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
- The "fingertip unit" can be used to measure appropriate amounts: the amount that covers from the tip of the index finger to the first crease covers approximately 2% of body surface area in an adult 2
Common Pitfalls to Avoid
- Using high-potency steroids on thin skin areas (face, intertriginous areas) increases risk of adverse effects 2
- Using low-potency steroids on thick plaques may result in treatment failure 2
- Lack of clear potency labeling on packaging can lead to patient confusion and dosing errors 4
- Prolonged use of any potency on the face can lead to rosacea and perioral dermatitis 2
Understanding the potency classification of topical corticosteroids is essential for optimizing treatment efficacy while minimizing potential adverse effects.