Therapy for head lice based on life cycle, resistance, and safety considerations.
The timing of head lice maturation most favorable to their survival in the presence of anti-lice agents is the maximum time as an ovum (12 days) and the shortest possible time of maturing from newly hatched nymph to egg-laying adult (8.5 days). Pediculicides that are not reliably ovicidal (pyrethroids and lindane) require 2 to 3 treatment cycles to eradicate lice. Ovicidal therapies (malathion) require 1 to 2 treatments. Treatment with an agent to which there is genetic resistance is unproductive. In the United States, lice have become increasingly resistant to pyrethroids and lindane but not to malathion. Treatment with malathion has favorable efficacy and safety profiles and enables the immediate, safe return to school. Nit combing can be performed adjunctively. No-nit policies should be rendered obsolete.
Lebwohl
Mark
M
Department of Dermatology, Mount Sinai School of Medicine, New York, NY 10029, USA.
Clark
Lily
L
Levitt
Jacob
J
D000818:Animals; D006801:Humans; D007305:Insecticide Resistance / Q000187:drug effects / Q000502:physiology*; D007306:Insecticides / Q000009:adverse effects* / Q000494:pharmacology / Q000627:therapeutic use; D010373:Lice Infestations / Q000188:drug therapy* / Q000503:physiopathology; D008018:Life Cycle Stages / Q000187:drug effects / Q000502:physiology*; D008294:Malathion / Q000009:adverse effects / Q000494:pharmacology / Q000627:therapeutic use; D010374:Pediculus / Q000187:drug effects / Q000254:growth & development*; D026023:Permethrin / Q000009:adverse effects / Q000494:pharmacology / Q000627:therapeutic use
D007306:Insecticides; D026023:Permethrin; D008294:Malathion