What is the recommended treatment for scabies?

Scabies Treatment

Topical 5% permethrin cream is the first-line treatment for uncomplicated scabies, applied from the neck down for 8-14 hours, with oral ivermectin (200 μg/kg, repeated in 2 weeks) as an equally effective alternative, except in children <15 kg, pregnant women, and lactating women where permethrin is strongly preferred. 1, 2

First-Line Treatment Options

Topical Permethrin 5% Cream

• Apply to all areas of the body from the neck down, including skin folds and creases 1, 2
• Leave on for 8-14 hours before washing off 1, 2
• One application is generally curative, though a second application 7-10 days later is recommended to ensure eradication 1, 2
• Take the cream directly from refrigerator and apply cold to the entire skin surface for enhanced effectiveness 3
• Pay particular attention to areas under fingernails, between fingers, wrists, axillary folds, abdomen, buttocks, and genitalia 4

Oral Ivermectin

• Dose: 200 μg/kg body weight, repeated in 2 weeks 1, 2
• Must be taken with food to increase bioavailability and epidermal penetration 2
• Equally effective as permethrin based on systematic reviews and meta-analyses 5
• No dosage adjustment needed for renal impairment 2

Special Populations

Pregnant and Lactating Women

• Use permethrin exclusively - it is the preferred and safest option 1, 2, 6
• Avoid ivermectin due to limited safety data in these populations 1, 6

Infants and Children

• Permethrin is safe and effective in children ≥2 months of age 1, 2, 7
• Avoid ivermectin in children weighing <15 kg due to neurotoxicity risk 1, 6
• Recent evidence suggests ivermectin may be safe in children >15 kg 5

Immunocompromised Patients

• Require closer monitoring as they are at increased risk for treatment failure 2
• May benefit from combination therapy similar to crusted scabies 2

Crusted (Norwegian) Scabies

Combination therapy is mandatory for crusted scabies:

• Topical 5% permethrin cream applied daily for 7 days, then twice weekly until cure 1, 2
• PLUS oral ivermectin 200 μg/kg on days 1,2,8,9, and 15 1, 2

Contact and Environmental Management

Contact Tracing and Treatment

• Examine and treat all persons with close personal, sexual, or household contact within the preceding month, even if asymptomatic 1, 2, 6
• Failure to treat contacts simultaneously is the most common cause of treatment failure 6

Environmental Decontamination

• Machine wash and dry bedding and clothing using hot cycle, or dry clean 2, 6
• Alternatively, remove items from body contact for at least 72 hours 2, 6
• Fumigation of living areas is unnecessary 2, 6

Follow-Up and Persistent Symptoms

Expected Post-Treatment Course

• Rash and pruritus may persist for up to 2 weeks after successful treatment - this does NOT indicate treatment failure 1, 2, 6
• In clinical trials, approximately 75% of patients with pruritus at 2 weeks had resolution by 4 weeks 7

When to Retreat

• Consider retreatment only after 2 weeks if symptoms persist AND live mites are observed 1, 2, 6
• Reasons for persistent symptoms include treatment failure, reinfection from untreated contacts, inadequate application, or cross-reactivity with other household mites 2

Secondary Bacterial Infection

• If impetiginization is present, consider adding topical fusidic acid 2% cream to permethrin 5%, which shows significantly higher efficacy (95% vs 35% cure rate at day 14) 8
• Staphylococcus aureus is the most common secondary bacterial pathogen 8

Critical Pitfalls to Avoid

Application Errors

• Do not apply permethrin after bathing - this increases absorption and toxicity risk 2, 6
• Ensure application reaches under fingernails and to the edge of all body orifices 6
• Avoid contact with eyes; flush immediately with water if contact occurs 7

Medication Selection Errors

• Never use lindane in children <10 years, pregnant/lactating women, or persons with extensive dermatitis due to severe neurotoxicity risk 1, 2, 6
• Do not forget to repeat ivermectin dose at 2 weeks - single dose is insufficient 2, 6

Management Errors

• Do not expect immediate symptom resolution - allow up to 2-4 weeks before declaring treatment failure 2, 7
• Do not retreat prematurely based on persistent itching alone without evidence of live mites 1, 2

Alternative Treatments (Less Preferred)

• Crotamiton 10% cream: Less effective than permethrin (60% vs 89% cure rate at 4 weeks), requires application for 2 consecutive nights 9, 10
• Lindane 1%: Should be avoided due to neurotoxicity concerns 2, 6
• Sulfur 6% ointment: Applied for 3 consecutive nights, less cosmetically elegant 6