What are the recommended topical and systemic treatments for scabies, and how do they differ in efficacy?

Recommended topical treatments for scabies in the UK include permethrin 5% cream, which is the first-line treatment licensed for use from 2 months of age onwards. Malathion aqueous 0.5% liquid is an alternative if permethrin is contraindicated, for example due to allergy, but it is currently unavailable. Benzyl benzoate 25% emulsion is generally no longer recommended due to lower efficacy and higher skin irritation risk compared to permethrin and malathion ¹.

Systemic treatment involves oral ivermectin, which was licensed in the UK in March 2024 for human scabies treatment. Ivermectin is effective, especially in cases of permethrin-resistant scabies or crusted scabies, but its failure rates vary widely (7-70%) and it has been found inferior to permethrin in some randomized controlled trials ¹.

Comparative efficacy of treatments shows that permethrin has a significantly higher cure rate than malathion, benzyl benzoate, crotamiton, and lindane/sulfur. Combination treatment with permethrin and oral ivermectin may have a non-significantly higher cure rate than permethrin alone. A Cochrane review found no significant difference in efficacy between topical permethrin and systemic or topical ivermectin, with few and mild adverse events reported overall ¹.

For persistent or resistant scabies, a second dose of ivermectin within 2 weeks may be considered if new lesions appear or parasitological examination remains positive. For profuse or crusted scabies, combination topical and systemic treatment may be necessary, and specialist referral is advised for nodular scabies ¹.