What is the treatment for scabies?

Treatment of Scabies

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

First-Line Treatment Options

• Permethrin 5% cream is the most effective topical treatment for scabies, with higher cure rates compared to other agents 1, 4
• Apply permethrin thoroughly to the entire body from the neck down in adults (including scalp, temple, and forehead in infants and elderly), leave on for 8-14 hours, then wash off 3
• Approximately 30 grams is sufficient for an average adult 3
• Oral ivermectin (200 μg/kg, repeated in 2 weeks) is an effective alternative first-line treatment for uncomplicated scabies 1, 2
• Ivermectin should be taken with food to increase bioavailability and penetration into the epidermis 1

Special Populations

• Permethrin is particularly recommended for:
  • Infants and young children 1, 2
  • Pregnant or lactating women due to limited safety data for ivermectin 1, 2
• Ivermectin is not recommended for children weighing less than 15 kg due to potential neurotoxicity 2
• Alternative treatments include:
  • Crotamiton (applied for 2 consecutive days, with bathing 48 hours after the last application) 5
  • Sulfur 6% ointment (considered safe but less effective than permethrin) 6
  • Lindane 1% (avoid in children <10 years, pregnant/lactating women, and persons with extensive dermatitis due to neurotoxicity risk) 1, 2

Management of Crusted (Norwegian) Scabies

• Combination therapy is recommended for crusted scabies: 1, 2
  • Topical permethrin 5% cream applied daily for 7 days, then twice weekly until cure
  • PLUS oral ivermectin 200 μg/kg on days 1,2,8,9, and 15

Management of Contacts and Environment

• All persons who have had sexual, close personal, or household contact with the patient within the preceding month should be examined and treated simultaneously, even if asymptomatic 1, 2
• Decontaminate bedding and clothing by: 1
  • Machine washing/drying using hot cycle
  • Dry cleaning
  • Removing from body contact for at least 72 hours
• Fumigation of living areas is unnecessary 1

Follow-Up and Treatment Failure

• Rash and pruritus may persist for up to 2 weeks after successful treatment (this is rarely a sign of treatment failure) 1, 2, 3
• Consider retreatment after 2 weeks if: 1, 2
  • Symptoms persist beyond 2 weeks
  • Live mites are observed
• Common reasons for treatment failure include: 1
  • Failure to treat all close contacts simultaneously
  • Inadequate application of topical treatments
  • Using lindane after bathing or in contraindicated populations
  • Not repeating ivermectin dose after 2 weeks

Treatment Efficacy Comparison

• Permethrin has shown superior efficacy compared to oral ivermectin in direct comparisons (92.5% vs 85.9% cure rate at 2 weeks) 7
• Permethrin is more effective than topical crotamiton and lindane in controlled trials 4
• Ivermectin may not be effective against all life cycle stages of the parasite, explaining why a second dose is needed 7
• For immunocompromised patients, closer monitoring is necessary as they are at increased risk for treatment failure 1

Common Pitfalls to Avoid

• Failing to apply permethrin thoroughly to all skin areas, including under fingernails 6
• Not treating all household and sexual contacts simultaneously, leading to reinfection 1, 2
• Expecting immediate resolution of symptoms (itching may persist for up to 2 weeks after successful treatment) 1, 3
• Using lindane in contraindicated populations (children <10 years, pregnant women, extensive dermatitis) 1, 2
• Not repeating ivermectin dose after 2 weeks 1