A risk-benefit assessment of agents used in the treatment of scabies.

Permethrin is probably the most effective topical treatment for scabies. There is little microbial resistance to the drug, and it is highly effective. Toxicity is limited to occasional contact dermatitis. Similarly, oral ivermectin 200 micrograms/kg is extremely effective. Oral administration eliminates the need to be certain that medication has been applied properly. Toxicity has been very limited. It is not available in the US for human use in scabies at this time. The toxicity of most of other treatments that are available has not been studied carefully. Sulphur 6% in petrolatum is recommended as safe, but there are no good studies to confirm this. Sulphur is probably the medication of choice when cost is the overriding concern. Crotamiton and benzyl benzoate are probably safe, but are not as effective as permethrin. Lindane has some potential CNS toxicity if used incorrectly, and must be used carefully on damaged skin to avoid excessive absorption. It is important to stress that all household and sexual contacts must be treated, whether or not they have symptoms. Proper application of topical medications must be achieved, including under the fingernails, and up to the edge of all body orifices.