How are topical corticosteroids classified by potency and what are example agents for each potency category?

Topical Corticosteroid Potency Classification

Seven-Class System

Topical corticosteroids are classified into seven potency categories based on their vasoconstrictor activity, ranging from ultra-high potency (Class 1) to low potency (Classes 6-7). 1

Class 1: Ultra-High Potency

• Clobetasol propionate 0.05% 1, 2
• Halobetasol propionate 0.05% 1, 2
• Efficacy: 58-92% 1
• Maximum duration: 2-4 weeks continuous use, with ≤50 grams per week 1, 2

Class 2: High Potency

• Betamethasone dipropionate 0.05% 1
• Fluocinonide 0.05% 1
• Amcinonide 0.1% 1
• Efficacy: 68-74% 1
• Maximum duration: Up to 4 weeks 1

Classes 3-4: Medium Potency

• Fluticasone propionate 0.005% ointment (Class 3) 1
• Betamethasone valerate foam (Class 4) 1
• Mometasone furoate 0.1% 1
• Efficacy: 68-72% 1
• Can be used for up to 12 weeks under supervision 1

Class 5: Medium-Low Potency

• Hydrocortisone 17-butyrate 21-propionate cream 1
• Fluticasone propionate cream 3
• Efficacy: 41-83% 1

Classes 6-7: Low Potency

• Hydrocortisone 1% 1
• Hydrocortisone 2.5% 3, 1
• Efficacy: 41-83% 1
• No specified time limit for use 1

Site-Specific Selection Algorithm

High-Risk Anatomical Sites (Use ONLY Classes 5-7)

• Face, neck, genitals, and intertriginous areas (axillae, groin, inframammary, intergluteal) require low-potency agents due to increased percutaneous absorption and high atrophy risk 3, 1
• Class 1 steroids are absolutely contraindicated on the face and body folds—all users developed atrophy after only 8 weeks 1

Trunk and Extremities

• Start with Class 2-3 (high potency) for initial control: betamethasone dipropionate 0.05%, fluocinonide 0.05%, or mometasone furoate 0.1% once or twice daily 1
• For chronic plaques, Class 1 may be used for 2-4 weeks maximum 1, 2

Thick Keratotic Lesions (Palms, Soles, Elbows, Knees)

• Require Class 1 ultra-high potency agents (clobetasol propionate 0.05%) due to thick stratum corneum limiting penetration 1, 2
• Low-to-medium potency agents are ineffective in these locations 1

Scalp

• All classes can be used for up to 4 weeks 1
• Betamethasone valerate foam (Class 4) achieved 72% improvement versus 47% placebo 1

Age-Specific Considerations

Pediatric Patients

• Use low-potency agents (Classes 5-7) due to higher skin-surface-to-body-mass ratio and greater systemic absorption risk 3, 1
• Infants and young children have increased risk of adrenal suppression from potent steroids 3
• Prolonged use may cause growth retardation 1

Geriatric Patients

• Thin, sun-damaged skin on forearms and face requires Class 6-7 agents to avoid atrophy 1
• Chronically sun-exposed skin increases adverse effect risk from higher-potency steroids 1

Critical Safety Warnings

Local Adverse Effects

• Skin atrophy, telangiectasia, striae, and purpura occur in only 1% of patients, with just 2 cases linked to Class 4 steroids across 22 trials 1
• Risk increases with higher potency, longer duration, larger areas, and sensitive sites 1

Systemic Effects

• Class 1 steroids can suppress the hypothalamic-pituitary-adrenal axis, especially with >50 grams weekly or occlusive dressings 1, 2
• Never use occlusive dressings with halobetasol or clobetasol—this dramatically increases systemic absorption 2

Occlusion Potency Shift

• Occlusion can elevate a Class 5 agent to Class 1 potency: 0.1% flurandrenolide functions as Class 5 cream but Class 1 tape 3

Tachyphylaxis Myth

A 12-week study found zero evidence of glucocorticoid receptor down-regulation with continuous use—perceived "tachyphylaxis" is actually poor patient adherence, not pharmacologic tolerance. 3, 1 When response diminishes, increase potency or improve adherence rather than switching to lower-potency agents 1

Steroid-Sparing Strategies

Proactive Maintenance Therapy

• Apply low-to-medium potency steroids (fluticasone, mometasone) twice weekly to previously affected areas for up to 16 weeks to prevent relapses in moderate-to-severe disease 3

Combination Therapy

• Combining vitamin D analogs with potent corticosteroids outperforms either agent alone 1, 2
• Fixed combination calcipotriene 0.005% plus betamethasone dipropionate 0.064% achieves 69-74% clear/almost clear status at 52 weeks with no serious adverse events 1
• Maximum vitamin D analog dose: 100 grams per week to avoid hypercalcemia 2

Rotational Strategy

• Start with Class 1 twice daily for initial control, add vitamin D analog twice daily, then shift to weekend-only corticosteroid while maintaining vitamin D analog 5 days per week 2

When to Escalate to Systemic Therapy

Consider systemic treatment if: 2

• No improvement after 4 weeks of appropriate high-potency topical therapy
• Body surface area exceeds what can be safely treated topically
• Quality of life remains severely impacted despite optimal topical management
• Significant psoriatic arthritis requiring systemic treatment