Pediculosis humanus capitus infestations are common and classically present with intense pruritus of the scalp. Although many treatment options are available, lice are becoming more resistant to conventional therapies and severe clinical presentations are bound to become more prevalent. We present a case of treatment-resistant pediculosis capitus resulting in diffuse autoeczematization of the torso and extremities and severe crusting and scaling of the scalp, which we called “crusted lice.” This eruption differs from the well-described id reaction known as “pediculid” and represents a more dramatic manifestation of rampant infestation. This paper provides an up-to-date review of treatment options available for pediculosis humanus capitus, including newer medications like the ones that eventually led to resolution of our patient’s extreme infestation.

Ivermectin (IVM) is a broad-spectrum anti-parasitic drug with significant anti-inflammatory properties. The emergence of treatment resistance to lindane, permethrin, and possibly malathion complicates the global strategy for management of common parasitic skin diseases such as scabies and head lice. In this regard. IVM has been safely and effectively used in the treatment of these common human infestations. In addition, IVM may be useful in inflammatory cutaneous disorders such as papulopustular rosacea where demodex may play a role in pathogenesis. Herein, we review the current applications of topical IVM in dermatology.