Treatment of Scabies
Permethrin 5% cream is the first-line treatment for uncomplicated scabies, applied from the neck down to all body areas, left on for 8-14 hours, then washed off, with a single application generally being curative. 1, 2
First-Line Treatment Options
Topical Permethrin 5% Cream
- Apply to the entire body surface from the neck down, including all skin folds, creases, under fingernails, and up to the edge of all body orifices 1
- Leave on skin for 8-14 hours (overnight application is practical), then wash off 1, 2
- One application is typically curative in most cases 2
- Preferred for pregnant/lactating women, infants, and young children due to its safety profile 1, 2
- The FDA label notes that approximately 75% of patients who still have itching at 2 weeks will have complete resolution by 4 weeks 3
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 1
- Contraindicated in children weighing less than 15 kg due to neurotoxicity risk 2
- Avoid in pregnant/lactating women due to limited safety data 2
- No dosage adjustment needed for renal impairment 1
- The second dose at 2 weeks is essential to address ivermectin's limited ovicidal activity 1
Special Populations
Infants Less Than 2 Months Old
- Use permethrin 5% cream only 2
- Do not use ivermectin due to neurotoxicity risk 2
- Avoid lindane completely in this age group 2
Pregnant and Lactating Women
- Permethrin 5% cream is the exclusive recommended treatment 2, 4
- Ivermectin should be avoided due to insufficient safety data 2
Crusted (Norwegian) Scabies
- Requires aggressive combination therapy due to massive mite burden (thousands to millions of mites) 1
- Regimen: Topical permethrin 5% 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 1, 2
- Single-application permethrin or single-dose ivermectin alone will fail 1
- This population is often immunocompromised, making them particularly vulnerable to treatment failure 1
Alternative Treatments (When First-Line Options Unavailable)
- Lindane 1%: Apply for 8 hours, but has significant limitations 4
- Sulfur 6% ointment: Apply for 3 consecutive nights 4
- Benzyl benzoate 25% lotion: Alternative option 5
Critical Management of Contacts and Environment
Contact Treatment
- Examine and treat ALL persons with close personal, sexual, or household contact within the preceding month 1, 2
- Treat contacts simultaneously, even if asymptomatic - failure to do this is the most common cause of treatment failure 4
Environmental Decontamination
- Machine wash and dry all bedding, clothing, and towels using hot cycles 1, 2
- Alternatively, dry clean items or remove from body contact for at least 72 hours 1
- Fumigation of living areas is unnecessary 1, 4
Follow-Up and Expected Course
Normal Post-Treatment Symptoms
- Pruritus and rash may persist for up to 2 weeks after successful treatment - this does NOT indicate treatment failure 1, 2
- Approximately 75% of patients with persistent itching at 2 weeks will have complete resolution by 4 weeks 3
When to Retreat
- Consider retreatment only after 2 weeks if symptoms persist AND live mites are observed 1, 2
- Reevaluate at 1-2 weeks, but avoid premature retreatment 2
Common Pitfalls to Avoid
- Failing to treat all close contacts simultaneously - the leading cause of treatment failure 4
- Inadequate application of topical permethrin - must cover entire body from neck down, including under nails and all body folds 1
- Not repeating ivermectin dose at 2 weeks - essential for complete eradication 1
- Using lindane after bathing - dramatically increases absorption and neurotoxicity risk 1, 4
- Expecting immediate symptom resolution - itching can persist 2 weeks after successful treatment 1, 2
- Using single-dose therapy for crusted scabies - will invariably fail given the massive mite burden 1
- Premature retreatment - wait at least 2 weeks before considering treatment failure 1, 2