Treatment of infestation with Phthirus pubis: comparative efficacies of synergized pyrethrins and gamma-benzene hexachloride.

In recent years there has been a steady increase in the incidence of infestation with Phthirus pubis, a sexually transmitted louse. A recently introduced nonprescription liquid pediculicide, whose major ingredient is 0.3% pyrethrins synergized by 3.0% piperonyl butoxide (RiD), was compared for efficacy and safety with a prescription-only pediculicidal lotion whose major ingredient is 1% gamma-benzene hexachloride (Kwell). Thirty adult man and women with P. pubis infestation were assigned randomly to treatment with either the synergized pyrethrins or gamma-benzene hexachloride. A single 10-min application of the synergized-pyrethrin liquid produced the same results as a single 12-hr application of the gamma-benze hexachloride lotion: total eradication of adult lice and nymphs, cessation of pruritus, and no treatment-induced side effect. A follow-up visit a week after treatment verified all eradications.