What is the first‑line treatment for scabies and how should it be managed in pregnant or lactating women, infants, young children, and severe crusted scabies?

First-Line Treatment for Scabies

Permethrin 5% cream is the recommended first-line treatment for scabies in all populations, applied from the neck down (entire body including scalp in infants and young children ≤2 years), left on for 8-14 hours, then washed off. 1, 2

Standard Treatment Protocol

General Population

• Apply permethrin 5% cream to the entire body from the neck down, including under fingernails, between fingers and toes, and all body folds 1, 2
• Leave on for 8-14 hours (typically overnight), then wash off 1, 2
• A single application is generally curative in uncomplicated cases 1, 2

Oral Alternative

• Oral ivermectin 200 μg/kg is an equally effective alternative, repeated after 2 weeks 1, 2, 3
• Must be taken with food to ensure adequate bioavailability and epidermal penetration 1, 2
• Recent evidence confirms ivermectin is as effective and safe as topical permethrin 4, 3

Special Populations

Pregnant and Lactating Women

Permethrin 5% cream is the only recommended treatment for pregnant or lactating women 1, 2, 5

• Ivermectin lacks sufficient safety data in pregnancy and should be avoided 1, 5
• Permethrin can be safely used during lactation 1

Infants and Young Children

Infants and children ≤2 years require whole-body application including scalp, hairline, forehead, temples, and neck 1

• Permethrin is safe even in infants <2 months old 1, 4
• Oral ivermectin is absolutely contraindicated in children weighing <15 kg or younger than 10 years due to potential blood-brain barrier penetration and neurotoxicity 1, 5
• Children ≥10 years (or ≥15 kg) may use neck-down application only, unless immunocompromised 1

Crusted (Norwegian) Scabies

Crusted scabies requires aggressive combination therapy with specialist consultation 1, 2:

• Topical permethrin 5% 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
• Single-agent therapy will fail due to massive mite burden (thousands to millions of mites) 2

Contact and Environmental Management

Simultaneous Treatment of Contacts

All household members, close contacts, and sexual partners within the prior month must be treated simultaneously, even if asymptomatic 1, 2, 5

• Failure to treat asymptomatic contacts is the most common cause of treatment failure and reinfection 1, 5

Environmental Decontamination

Machine-wash and dry all bedding, clothing, and towels on hot cycles 1, 2, 5

• Alternatively, dry-clean or isolate items from skin contact for ≥72 hours (mites cannot survive off-host longer than this) 1, 2, 5
• Fumigation of living areas is not required 1, 2, 5

Post-Treatment Course and Retreatment

Expected Symptoms

Pruritus and rash may persist for up to 2 weeks after successful therapy due to allergic dermatitis, not treatment failure 1, 2, 5

• This does not indicate need for immediate retreatment 1, 2

Retreatment Criteria

Retreatment is indicated only after 2 weeks if:

• Live mites are observed on examination 1, 2, 5
• Symptoms persist beyond 2 weeks 1, 2, 5
• New lesions continue to appear 1
• Use an alternative regimen (switch between permethrin and ivermectin) if retreatment is needed 1

Treatments to Avoid

Lindane

Lindane should never be used in 1, 2, 5:

• Children <10 years (high risk of seizures and neurotoxicity) 1, 2, 5
• Pregnant or lactating women 1, 2, 5
• Persons with extensive dermatitis 1, 2, 5
• Never apply lindane after bathing, as this increases systemic absorption and toxicity 1, 2

Alternative Agents (When Permethrin Unavailable or Fails)

Recent evidence suggests benzyl benzoate 25% may be superior to permethrin, with an 87% cure rate versus 27% for permethrin in a 2024 head-to-head trial 6, 3

• Applied daily for 3 consecutive days 3
• Causes burning sensation in 14-43% of patients but is otherwise well-tolerated 6, 3

Sulfur 6% ointment applied nightly for 3 consecutive nights (wash off before each reapplication) 1, 5

Common Pitfalls to Avoid

• Not treating asymptomatic contacts simultaneously leads to reinfection 1, 5
• Premature retreatment within 2 weeks based solely on persistent itching is unnecessary 1
• Forgetting to repeat ivermectin dose at 2 weeks allows incomplete eradication 2, 5
• Inadequate application (missing under nails, body folds, or scalp in young children) 1