Scabies Treatment
First-Line Therapy
Permethrin 5% cream is the recommended first-line treatment for scabies in all patient populations, applied to the entire body (neck down in adults, scalp-to-toes in infants and young children) for 8-14 hours, then washed off. 1, 2
- A single application is generally curative for uncomplicated scabies. 1, 2
- Oral ivermectin 200 μg/kg (repeated in 2 weeks) is an equally effective alternative first-line option, particularly useful when topical application is impractical or during institutional outbreaks. 1, 2
- Ivermectin must be taken with food to ensure adequate bioavailability and epidermal penetration. 1, 2
Age-Specific Application Guidelines
Infants and Young Children (≤2 years)
- Apply permethrin to the entire body including scalp, hairline, forehead, temples, and neck because mites commonly infest these areas in young children. 1
- Oral ivermectin is contraindicated in children weighing <15 kg or younger than 10 years due to risk of blood-brain barrier penetration and neurotoxicity. 1
Older Children and Adults (≥10 years or ≥15 kg)
- Apply permethrin from the neck down only, unless the patient is immunocompromised. 1
- Oral ivermectin becomes a safe alternative in this age group. 1
Special Populations
Pregnant or Lactating Women
- Permethrin 5% cream is the preferred treatment because ivermectin lacks sufficient safety data in pregnancy and lactation. 1, 2
- Ivermectin is classified as "low-risk" based on limited human data but should be avoided when permethrin is available. 1
Elderly Patients
- Standard permethrin 5% cream applied neck-down is appropriate. 2
- Consider scalp-to-toes application if head involvement is suspected, as elderly patients may have atypical presentations. 3
Crusted (Norwegian) Scabies
Crusted scabies requires aggressive combination therapy with both topical and oral medications plus specialist consultation. 1, 2
- Topical permethrin 5% cream applied daily for 7 days, then twice weekly until cure. 1, 2
- Oral ivermectin 200 μg/kg on days 1,2,8,9, and 15. 1, 2
- Single-application permethrin or single-dose ivermectin will fail due to the massive mite burden (thousands to millions of mites). 2
- Remove thick crusts and cut nails to improve medication penetration. 4
Alternative Topical Treatments (when permethrin unavailable or fails)
- Sulfur 6% ointment applied nightly for 3 consecutive nights (wash off before each reapplication). 1
- Crotamiton 10% cream applied nightly for 2 nights, washed off 24 hours after the second application—shows ~60% cure rate versus ~89% for permethrin. 1
- Benzyl benzoate 25%—~87% cure rate but causes burning sensation in ~43% of patients. 1
Contact and Environmental Management
All household members, close contacts, and sexual partners within the prior month must be treated simultaneously, even if asymptomatic. 1, 2
- Failure to treat contacts simultaneously is the most common cause of treatment failure and reinfection. 2, 5
- Machine-wash and dry all bedding, clothing, and towels on hot cycles, or dry-clean, or isolate from skin contact for ≥72 hours. 1, 2
- Scabies mites cannot survive off-host for longer than 72 hours. 1
- Fumigation of living areas is not required. 1, 2
Expected Post-Treatment Course
Pruritus and rash may persist for up to 2 weeks after successful therapy due to allergic dermatitis, not treatment failure. 1, 2
- Do not retreat based solely on persistent itching within the first 2 weeks. 1
- Retreatment is indicated only after 2 weeks if live mites are observed, symptoms persist beyond 2 weeks, or new lesions continue to appear. 1, 2
- Use an alternative regimen (switch between permethrin and ivermectin) if retreatment is needed. 2
Treatments to Avoid
Lindane should never be used in children <10 years, pregnant or lactating women, or patients with extensive dermatitis due to high risk of seizures, neurotoxicity, and aplastic anemia. 1, 2
- Applying lindane after bathing increases systemic absorption and toxicity. 2, 5
- Lindane has the highest toxicity profile among scabicidal agents despite being inexpensive. 1
Common Pitfalls
- Failing to treat asymptomatic sexual partners and household contacts is the most frequent cause of reinfection. 1, 5
- Not repeating the ivermectin dose at 2 weeks allows surviving mites to repopulate. 2, 5
- Inadequate application of topical permethrin—must apply under nails and to all body folds. 5
- Premature retreatment within 2 weeks based on persistent itching alone leads to unnecessary medication exposure. 1
- Using corticosteroids during active treatment can suppress inflammatory responses that help identify active infestation and may allow mites to proliferate. 2