What is the recommended treatment for scabies crusted (Norwegian scabies)?

Treatment of Crusted (Norwegian) Scabies

The recommended treatment for crusted (Norwegian) scabies is combination therapy with oral ivermectin (200 μg/kg) and topical permethrin 5% cream, with multiple doses of ivermectin required for effective treatment. 1, 2

First-line Treatment Regimen

• Oral ivermectin: 200 μg/kg (0.2 mg/kg) with food

  • Multiple doses required (typically 2-3 doses)
  • Doses should be given 14 days apart
  • Food increases bioavailability and enhances epidermal penetration 1

• Topical permethrin 5% cream:

  • Apply from neck down to entire body
  • Leave on for 8-14 hours before washing off
  • May need repeated applications 1

Treatment Protocol Based on Severity

1. For severe crusted scabies:

   • Three doses of oral ivermectin (days 1,2, and 8)
   • Combined with daily topical permethrin applications for 7 days
   • Then twice weekly until resolution 2

2. For moderate cases:

   • Two doses of oral ivermectin (days 1 and 8)
   • Combined with topical permethrin applications 1

Special Considerations

• Immunocompromised patients (transplant recipients, HIV patients, those on immunosuppressive therapy) are at higher risk for crusted scabies and require more aggressive treatment 1, 2

• Diagnosis confirmation:

  • Skin scrapings from crusted lesions are essential
  • Skin biopsy may be necessary in atypical presentations 2

• Treatment failure signs:

  • Persistence of symptoms beyond 2 weeks
  • Observation of live mites
  • Appearance of new lesions 1

Environmental Control Measures

• All bedding and clothing must be washed in hot water or dry cleaned
• Items that cannot be washed should be removed from body contact for at least 72 hours
• All household members and close contacts should be treated simultaneously, even if asymptomatic 1

Monitoring and Follow-up

• Evaluate treatment effectiveness after 2-4 weeks
• Be aware that persistent pruritus may continue for up to 2 weeks after successful treatment
• Consider retreatment if symptoms persist 1

Common Pitfalls

1. Misdiagnosis: Crusted scabies is frequently overlooked due to atypical presentations, especially in immunocompromised patients 3, 2

2. Insufficient treatment: Single-dose ivermectin is inadequate for crusted scabies; multiple doses are necessary 4, 5

3. Neglecting environmental decontamination: Failure to treat the environment and close contacts leads to reinfestation 1

4. Inadequate follow-up: Recurrence is common (observed in at least half of cases), requiring vigilant monitoring 4

While older literature supported lindane as treatment 3, more recent guidelines favor ivermectin and permethrin due to their superior safety profile and efficacy 1, 2. The combination of oral ivermectin and topical permethrin has demonstrated excellent clinical outcomes in recent cases 2.