What is the recommended treatment regimen for scabies, including first‑line therapy, alternative options, dosing for adults, children, pregnant or lactating women, management of close contacts, and treatment of crusted (Norwegian) scabies?

Scabies Treatment

First-Line Therapy

Permethrin 5% cream is the recommended first-line treatment for scabies across all age groups. 1, 2, 3 Apply from the neck down to the soles of the feet, leave on for 8-14 hours, then wash off. 2, 3 One application is generally curative. 1, 3

Age-Specific Application Differences

• Infants and children ≤2 years require whole-body application including scalp, hairline, forehead, temples, and neck because scabies commonly infests these areas in young children. 1, 3
• Children ≥10 years and adults apply from neck down only, unless immunocompromised. 1
• Approximately 30 grams is sufficient for an average adult. 3

Alternative First-Line Option: Oral Ivermectin

Oral ivermectin 200 μg/kg is an effective alternative, repeated in 2 weeks. 1, 2 This option is particularly useful for institutional outbreaks or patients unable to comply with topical therapy. 1, 4

Critical Ivermectin Considerations

• Must be taken with food to ensure adequate bioavailability and epidermal penetration. 1, 2
• Contraindicated in children <15 kg or <10 years old due to potential blood-brain barrier penetration and neurotoxicity. 1
• No dosage adjustment needed for renal impairment. 2

Treatment of Special Populations

Pregnant and Lactating Women

Permethrin 5% cream is the only recommended treatment for pregnant or lactating women. 1, 2 Ivermectin lacks sufficient safety data in pregnancy and should be avoided. 1

Crusted (Norwegian) Scabies

Crusted scabies requires aggressive combination therapy with specialist consultation. 1, 2 The regimen includes:

• Topical permethrin 5% 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-application permethrin or single-dose ivermectin alone will fail due to the massive mite burden (thousands to millions of mites). 2

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 This is the most common cause of treatment failure when not followed. 2

Environmental Decontamination

• Machine wash and dry bedding, clothing, and towels on hot cycles, or dry-clean. 1, 2
• Alternatively, isolate items from skin contact for ≥72 hours because mites cannot survive off-host longer than this period. 1, 2
• Fumigation of living areas is not required. 1, 2

Post-Treatment Course and Retreatment Criteria

Pruritus and rash may persist for up to 2 weeks after successful therapy due to allergic dermatitis, not treatment failure. 1, 2, 3 This is rarely a sign of treatment failure and is not an indication for retreatment. 3

When to Retreat

• 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
• Demonstrable living mites after 14 days indicate that retreatment is necessary. 3
• Use an alternative regimen if retreatment is needed. 1

Alternative Topical Agents (When Permethrin Unavailable or Fails)

• Crotamiton 10% cream: Apply nightly for 2 nights, wash off 48 hours after the second application. 5 Shows ~60% cure rate at 4 weeks versus ~89% for permethrin. 1
• Sulfur 6% ointment: Apply nightly for 3 consecutive nights, washing off before each reapplication. 1, 2
• Benzyl benzoate 25%: ~87% cure rate but causes burning sensation in ~43% of patients. 1

Contraindicated Therapies

Lindane should never be used in children <10 years, pregnant or lactating women, or persons with extensive dermatitis due to high risk of seizures and neurotoxicity. 1, 2 If used in adults, never apply after bathing as this increases absorption and toxicity risk. 2

Institutional Outbreak Management

During outbreaks, treat the entire at-risk population concurrently. 1 Mass oral ivermectin is recommended for ease of administration. 1 Outbreak response should involve specialist consultation to coordinate treatment and control measures. 1

Common Pitfalls to Avoid

• Failing to treat all close contacts simultaneously is the most common cause of treatment failure. 2
• Not repeating ivermectin dose at 2 weeks leaves residual infestation. 2
• Expecting immediate symptom resolution—remember that post-treatment pruritus lasting up to 2 weeks is normal. 1, 2
• Using topical corticosteroids during active treatment can suppress inflammatory response and allow mites to proliferate; only consider after treatment completion if pruritus persists beyond 2 weeks and live mites are absent. 2