Severe forms of scabies (crusted scabies and profuse scabies) require a specific treatment. Ivermectin is a recommended treatment in common forms of scabies and represents a promising treatment in crusted scabies in case reports. However, response to ivermectin remains variable among studies, and there is no consensus on the schemes to adopt (dosages and administrations). Ivermectin at 400 µg/kg has already been used, without showing toxicity (in head lice treatment in particular). Investigators propose to demonstrate that 400µg/kg ivermectin dosage will show better efficacy than a 200µg/kg in patients with severe forms of scabies (crusted and profuse).

Inclusion Criteria:

Patients ≥ 18 years old, diagnosed with severe forms of scabies

1. clinical criteria : cutaneous lesions of scabies

   • crusted scabies: at least two sites of hyperkeratosis will define crusted scabies and/or
   • profuse scabies : spreading lesions with erythematous scaly eruption of the neck, face or trunk without hyperkeratosis

2. paraclinical criteria:

   • Positive parasitological test
   • and/or dermoscopic exam with signs of scabies

Effective contraception for women in age of pregnancy Written consent from patient or his/her legal representant, trustworthy person or family member Affiliated to a social security scheme

Exclusion Criteria:

• Pregnant and/or breastfeeding women
• Intolerance to ivermectin or topical treatment (permethrin 5% cream) or emollient cream
• Use of anti parasitic drug (ivermectin or albendazole) within the past 7 days
• Abnormal liver test results: ALT and/or AST >3N within the past 7 days (within 6 months if no hepatic history)
• Participation in other biomedical drug research
• Patient deprived of freedom
• Any psychological, familial, sociological or geographical condition potentially hampering compliance with the study protocol and follow-up schedule