What is the recommended treatment for household contacts of an infant with scabies, including first‑line and alternative options?

Treatment for Household Contacts of an Infant with Scabies

All household members, close contacts, and anyone who has had prolonged skin-to-skin contact with the infant within the preceding month must be treated simultaneously—even if completely asymptomatic—to prevent reinfection and treatment failure. 1, 2

Why Treat Asymptomatic Contacts

• Scabies has a 4–6 week incubation period during which infected persons remain contagious despite having no symptoms, making untreated contacts the most common cause of treatment failure in the index patient. 3
• Treating only the symptomatic infant permits asymptomatic household members to reinfest the baby within days to weeks after successful therapy, creating a transmission cycle that can persist for months. 1, 3
• Failure to treat all close contacts simultaneously is the single most frequent cause of apparent treatment failure. 2, 3

First-Line Treatment for Contacts

Adults and Children ≥10 Years or ≥15 kg

• Permethrin 5% cream applied from the neck down to the soles of the feet, left on for 8–14 hours (overnight), then washed off; one application is generally curative. 1, 2, 4
• Oral ivermectin 200 µg/kg is an effective alternative, especially useful when topical application is impractical (e.g., in institutional settings or for patients with extensive skin disease); repeat the dose in 2 weeks. 1, 2, 3
• Ivermectin must be taken with food to ensure adequate bioavailability. 2, 3

Infants and Young Children <10 Years or <15 kg

• Permethrin 5% cream is the only recommended treatment for infants and young children. 1, 2
• In infants and young children ≤2 years, apply permethrin to the entire body including the scalp, hairline, forehead, temples, and neck—not just neck-down as in adults. 2, 4
• Oral ivermectin is contraindicated in children weighing <15 kg due to potential neurotoxicity from blood-brain barrier penetration. 1, 2

Pregnant or Lactating Women

• Permethrin 5% cream is the preferred treatment due to limited safety data for ivermectin in pregnancy and lactation. 1, 2, 3
• Ivermectin poses a low theoretical risk but lacks sufficient human data to recommend routinely. 1, 2

Alternative Topical Options (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.
• Benzyl benzoate 25% shows ~87% cure rate but causes burning sensation in ~43% of patients.

Treatments to Avoid in Household Contacts

• Lindane should never be used in children <10 years, pregnant or lactating women, or persons with extensive dermatitis due to high risk of seizures, neurotoxicity, and aplastic anemia. 1, 2, 5
• Applying lindane after bathing increases systemic absorption and toxicity. 1, 5

Environmental Decontamination (Essential Adjunct)

• Machine-wash and dry all bedding, clothing, and towels on hot cycles on the same day as treatment, or dry-clean them. 1, 2, 3
• Items that cannot be laundered should be isolated from skin contact for at least 72 hours, as scabies mites cannot survive off-host beyond this period. 1, 2, 3
• Fumigation of living areas is unnecessary. 1, 3

Expected Post-Treatment Course and When to Retreat

• Pruritus and rash commonly persist for up to 2 weeks after successful treatment due to allergic dermatitis—this does NOT indicate treatment failure or ongoing contagion. 1, 2, 3
• Retreatment is indicated only if symptoms persist beyond 2 weeks AND live mites are observed on skin examination. 1, 2, 4
• Premature retreatment within the first 2 weeks based solely on persistent itching should be avoided. 2, 3
• If retreatment is necessary, use an alternative regimen (e.g., switch from permethrin to ivermectin or vice versa). 1

Common Pitfalls to Avoid

• Not treating all household contacts at the same time is the most common cause of reinfection. 2, 3
• Inadequate application of topical permethrin (e.g., missing the scalp in infants, not covering all skin folds). 2, 6
• Not repeating the ivermectin dose after 2 weeks when using oral therapy. 6
• Expecting immediate resolution of symptoms—post-treatment pruritus is normal and expected. 1, 2, 3