What is the recommended treatment for scabies?

Scabies Treatment

Permethrin 5% cream applied from the neck down (including scalp in infants and elderly) for 8-14 hours is the first-line treatment for uncomplicated scabies, with one application generally being curative. 1, 2, 3

First-Line Treatment Options

Topical Permethrin (Preferred)

• Apply permethrin 5% cream to all areas of the body from the neck down and wash off after 8-14 hours 1, 2, 3
• In infants, young children, and geriatric patients, include the scalp, hairline, neck, temple, and forehead since these areas are commonly infested in these age groups 1, 3
• Approximately 30 grams is sufficient for an average adult 3
• One application is generally curative 3
• Permethrin is the preferred agent for pregnant women, lactating women, infants, and young children 1, 2, 4

Oral Ivermectin (Alternative First-Line)

• Ivermectin 200 μg/kg orally, repeated in 2 weeks 1, 2, 5
• Must be taken with food to increase bioavailability and penetration into the epidermis 1, 2
• Do NOT use in children weighing less than 15 kg due to potential neurotoxicity 4
• No dosage adjustments required for renal impairment, but safety of multiple doses in severe liver disease is unknown 1
• The second dose at 2 weeks is essential because ivermectin has limited ovicidal activity 1

Crusted (Norwegian) Scabies

Combination therapy is mandatory for crusted scabies due to heavy mite burden: 2, 5, 4

• Topical permethrin 5% cream applied daily for 7 days, then twice weekly until cure 2, 5, 4
• PLUS oral ivermectin 200 μg/kg on days 1,2,8,9, and 15 2, 5, 4

Alternative Regimens (Use Only If First-Line Fails or Cannot Be Tolerated)

• Lindane 1% applied for 8 hours, but avoid in children <10 years, pregnant/lactating women, and persons with extensive dermatitis due to neurotoxicity risk including seizures and aplastic anemia 1, 2, 5, 4
• Never apply lindane immediately after bathing as this increases absorption and neurotoxicity risk 1, 5
• Benzyl benzoate 25% lotion, malathion 0.5% aqueous lotion, or sulfur 6-33% ointment are other alternatives 6

Contact and Environmental Management

Contact Tracing and Treatment

• All persons with close personal, sexual, or household contact within the preceding month must be examined and treated simultaneously, even if asymptomatic 2, 5, 4
• Failure to treat all close contacts simultaneously is the most common cause of treatment failure 5
• Look-back period is 2 months for partner management 6

Environmental Decontamination

• Machine-wash and machine-dry bedding and clothing using hot cycle, or dry clean, or remove from body contact for at least 72 hours 1, 2, 5
• Mites survive on clothing for up to 4 days without skin contact but only 1-2 days at room temperature 5
• Fumigation of living areas is unnecessary 1, 2

Follow-Up and Persistent Symptoms

Expected Post-Treatment Course

• Rash and pruritus may persist for up to 2 weeks after successful treatment—this is NOT treatment failure 2, 5, 4
• Approximately 75% of patients with persistent pruritus at 2 weeks have resolution by 4 weeks 3
• This post-treatment pruritus is NOT an indication for retreatment 5, 3

When to Retreatment

• Retreatment is indicated ONLY if symptoms persist beyond 2 weeks AND demonstrable living mites are observed after 14 days 2, 5, 3
• Reasons for true treatment failure include inadequate application, reinfection from untreated contacts, or resistance 2

Critical Pitfalls to Avoid

1. Not treating all close contacts simultaneously—the leading cause of treatment failure 5
2. Inadequate topical application—must include under nails, all body folds, between fingers and toes, and up to edge of all orifices 5
3. Forgetting to treat the scalp in infants and elderly patients 1, 3
4. Using lindane after bathing—increases absorption and neurotoxicity risk 1, 5
5. Not repeating ivermectin dose at 2 weeks—essential for complete eradication due to limited ovicidal activity 1, 5
6. Expecting immediate symptom resolution—pruritus persists up to 2 weeks normally and does not indicate treatment failure 5, 3
7. Retreating too early for persistent symptoms—wait 14 days and confirm living mites before retreating 2, 5, 3

Special Populations

Pregnancy and Lactation

• Permethrin is the preferred treatment 1, 4
• Ivermectin is classified as "human data suggest low risk" in pregnancy and probably compatible with breastfeeding, but permethrin remains preferred 1
• Avoid lindane due to association with neural tube defects and mental retardation 1

HIV/Immunocompromised Patients

• Use the same treatment regimen as HIV-negative patients for uncomplicated scabies 1
• Monitor more closely as they are at increased risk for treatment failure and crusted scabies 2