What is the recommended treatment and management for a patient with scabies?

Treatment and Management of Scabies

Apply permethrin 5% cream from the neck down (or entire body including scalp in infants and young children) for 8-14 hours, then wash off—this single application is generally curative. 1, 2, 3

First-Line Treatment Options

Topical Permethrin 5% Cream (Preferred)

• Permethrin 5% cream is the CDC-recommended first-line treatment for all age groups, including infants, children, pregnant women, and lactating women. 1, 2
• Apply to the entire body from the neck down in adults and older children (≥10 years or ≥15 kg). 1
• In infants and young children (≤2 years), apply to the entire body including scalp, hairline, forehead, temples, and neck—this differs critically from adult application. 1
• Leave on for 8-14 hours (typically overnight), then wash off thoroughly. 1, 2, 3
• Usually 30 grams is sufficient for an average adult. 3
• One application is generally curative; retreatment is only indicated after 2 weeks if live mites are observed or symptoms persist beyond 2 weeks. 1, 2, 3

Oral Ivermectin (Alternative First-Line)

• Oral ivermectin 200 μg/kg is an effective alternative, repeated in 2 weeks. 1, 2
• Must be taken with food to ensure adequate bioavailability and epidermal penetration. 1, 2
• Contraindicated in children weighing <15 kg or younger than 10 years due to risk of neurotoxicity from blood-brain barrier penetration. 1, 2
• Particularly useful when topical application is impractical (e.g., institutional outbreaks, extensive dermatitis, poor adherence). 1, 2

Special Populations

Pregnant and Lactating Women

• Permethrin 5% cream is the preferred treatment due to limited safety data for ivermectin in pregnancy and lactation. 1, 2
• Ivermectin is classified as "low risk" based on limited human data, but permethrin remains the primary recommendation. 2

Infants <2 Months Old

• Permethrin can be considered for off-label use in infants <2 months. 1
• Ivermectin is contraindicated due to potential neurotoxicity. 1
• Apply permethrin to the entire body including scalp, face, and neck. 1

Crusted (Norwegian) Scabies

• Requires aggressive combination therapy: topical permethrin 5% cream applied daily for 7 days, then twice weekly, PLUS oral ivermectin 200 μg/kg on days 1,2,8,9, and 15. 1, 2
• Mandatory specialist consultation is required. 2
• Occurs most frequently in immunocompromised, debilitated, or malnourished patients and harbors thousands to millions of mites. 2
• Single-application permethrin or single-dose ivermectin alone will fail. 2
• Affected patients should be isolated. 2

Contact and Environmental Management

Simultaneous Treatment of Contacts

• All household members, sexual partners, and close contacts within the preceding month must be treated simultaneously, even if asymptomatic. 1, 2
• Failure to treat asymptomatic contacts is the most common cause of treatment failure and reinfection. 1, 2
• Scabies has a 4-6 week incubation period during which infected persons remain contagious despite being asymptomatic. 2

Environmental Decontamination

• Machine-wash and dry all bedding, clothing, and towels using hot cycles, or dry-clean them. 1, 2
• Alternatively, remove items from body contact for at least 72 hours (mites cannot survive off-host beyond 48-72 hours at room temperature). 1, 2
• Fumigation of living areas is unnecessary and not recommended. 1, 2

Expected Post-Treatment Course

Normal Post-Treatment Symptoms

• Pruritus and rash may persist for up to 2 weeks after successful treatment due to allergic dermatitis—this does NOT indicate treatment failure. 1, 2, 3
• Approximately 75% of patients with persistent pruritus at 2 weeks will have complete resolution by 4 weeks. 3
• Do not retreat based solely on persistent itching within the first 2 weeks. 1, 2

When to Retreat

• Retreatment is indicated only after 2 weeks if:
  • Live mites are observed on examination 1, 2, 3
  • Symptoms persist beyond 2 weeks 1, 2
  • New lesions continue to appear 1
• When retreating, switch to an alternative regimen (permethrin ↔ ivermectin). 2

Treatments to Avoid

Lindane

• Never use lindane in children <10 years, pregnant or lactating women, or patients with extensive dermatitis due to high risk of neurotoxicity (seizures) and aplastic anemia. 1, 2
• Applying lindane after bathing increases systemic absorption and toxicity—must be avoided. 1, 2
• Lindane has the highest toxicity profile among scabicidal agents. 1

Topical Corticosteroids During Active Treatment

• Do not apply triamcinolone or other topical corticosteroids during the permethrin or ivermectin treatment phase. 2
• Corticosteroids suppress the inflammatory response that helps identify active infestation and may allow mites to proliferate. 2
• Consider topical corticosteroids only after treatment completion if pruritus persists beyond 2 weeks AND live mites are confirmed absent. 2

Institutional Outbreak Management

• Treat the entire at-risk population simultaneously. 1, 2
• Mass oral ivermectin administration is recommended for ease of delivery in nursing homes, hospitals, and residential facilities. 1, 2
• Coordinate outbreak response with a scabies specialist. 1, 2

Common Pitfalls to Avoid

• Incomplete application of permethrin (missing under nails, between toes, in body folds, or genital areas). 1
• Treating only the symptomatic index case while leaving asymptomatic household contacts untreated. 1, 2
• Not repeating the ivermectin dose at 2 weeks. 2
• Premature retreatment within 2 weeks based solely on persistent itching. 1, 2
• Incomplete environmental decontamination of bedding and clothing. 2
• Using lindane in contraindicated populations or after bathing. 1, 2