What is the best treatment option for crusted scabies?

Treatment of Crusted Scabies

For crusted scabies, you must use aggressive combination therapy with both topical 5% permethrin cream applied daily for 7 days then twice weekly until cure, PLUS oral ivermectin 200 μg/kg on days 1,2,8,9, and 15—single-agent therapy will fail. 1, 2

Why Combination Therapy is Essential

Crusted scabies is fundamentally different from ordinary scabies and requires a completely different treatment approach:

• Massive mite burden: The skin harbors thousands to millions of mites (versus 10-15 in ordinary scabies), making single-agent therapy inadequate 1
• Thick crusts: The hyperkeratotic crusts prevent adequate penetration of topical agents alone 1
• High contagiousness: This variant is far more contagious than typical scabies and occurs primarily in immunodeficient, debilitated, or malnourished patients 1

The Specific Treatment Protocol

Topical Component

• Apply 5% permethrin cream daily for 7 consecutive days, then twice weekly until complete clearance 1, 2
• Apply to the entire body including scalp, face, and under nails 1
• Critical pitfall: Do NOT use the single-application regimen recommended for ordinary scabies—this will fail in crusted scabies 1

Oral Component

• Ivermectin 200 μg/kg on days 1,2,8,9, and 15 1, 2
• Take with food to increase bioavailability and epidermal penetration 1
• The multiple-dose schedule addresses ivermectin's limited ovicidal activity and the massive mite burden 1
• Critical pitfall: Do NOT skip the oral component—topical therapy alone is insufficient given the mite burden and thick crusts 1

Why This Regimen Works

• No controlled therapeutic studies exist for crusted scabies, but substantial treatment failure occurs with single-dose topical scabicide or oral ivermectin alone 1
• The combination addresses both the massive surface mite burden (topical) and systemic/deep tissue involvement (oral) 1
• Variable response has been documented with ivermectin monotherapy, with an inverse relationship between treatment response and severity of immunosuppression, crust thickness, and mite burden 3

Additional Management Considerations

Contact Tracing and Environmental Control

• Examine and treat ALL close contacts, household members, and caregivers within the preceding month simultaneously, even if asymptomatic 1, 2
• Decontaminate all bedding, clothing, and towels by machine washing/drying with hot cycles or dry cleaning 1
• Remove items from body contact for at least 72 hours if washing is not possible 1

Medications to Avoid

• Never use lindane in crusted scabies patients—they are often immunocompromised or debilitated, making them highly vulnerable to lindane neurotoxicity 1

Follow-Up Expectations

• Pruritus and rash may persist up to 2 weeks after successful treatment and do not indicate treatment failure 1, 2
• Consider retreatment only if symptoms persist beyond 2 weeks AND live mites are observed 1, 2
• Immunocompromised patients require closer monitoring as they are at increased risk for treatment failure 1