Head Lice – That Lousy Louse!

That Lousy Louse!


No, Lice does not constitute a medical emergency… you know that… I know that… but parents will freak out if they are concerned that their child might have lice.  So, that will, inevitably, lead them to the nearest care-provider possible.  In turn, that usually makes us all itch as well.  So, before we all excoriate our scalps, let’s see what needs to be done.

a)    Louse Hysteria leads to poor decisions! People have used dangerous methods to rid their children of lice:
i)    Bleach, acetone, WD-40, … gasoline!
ii)    Shaving the kids head… this is actually effective, but drastic.

b)    Head Lice is not a health hazard!
c)    Head Lice is not a sign of poor hygiene!
d)    Head Lice do not spread disease (unlike body lice).
e)    Children should not be restricted from attending school!

f)    Adult head lice are 2-3 mm long (size of sesame seed) and are tanish in color. They have 6 legs.
g)    Female can lay 10 eggs per day at the base of the hair shaft, often in the posterior hairline.

h)    Transmission (this will make you feel less itchy!)
i)    Lice cannot hop or fly!
ii)    Lice crawl.
iii) Transmission most often occurs by direct contact with the affected individual’s head or that individual’s personal belongings (hats, combs, carseats, etc)

i)    Treatment
i)    Resistance to over the counter treatments is increasing.  It is best to treat based on your resistance patterns in your community.
(1) Permethrin 1%
(a) Most studied in the US.
(b) Least toxic pediculicide.
(c) Retreatment recommended in 1 week.
(d)  Available over the counter.
(2) Malthion 0.5%
(a) This is an organophosphate!
(b) Available only by prescription.
(c) High ovicidal activity.
(d) Single application is adequate for most patients.
(e) Reapplication is live lice are seen in ~1 week.
(f)     Contraindicated in kids <2yrs of age!
(g) Highly flammable (as it has a 78% isopropyl alcohol content!)
(3) Pyrethrins plus Piperonyl Butoxide
(a) Neurotoxic to lice, but low mammalian toxicity.
(b) Derived from chrysanthemums (so don’t use if pt allergic to them)
(c) Recommended treatment at Days 0, 7, 13, and 15 (as ova don’t have nervous systems)
(4) Benzyl Alcohol 5%
(a) For kids >6months
(b) Kills by asphyxiation (sweet!)
(c) Treatment on Days 0, 7, 13 and +/- 15).
(5) Lindane
(a) Is toxic to humans! Enough said.
ii)    There are many other products used “off-label”… but let’s stick with on label for now.
iii) There are also many other “home-remedies” using petroleum products to suffocate the adult louse.  Feel free to peruse the vast array of those on the internet.
iv) Don’t forget the fomites!
(1) Any item that comes in contact with the patient’s head should be cleaned.
(2) Washing, soaking, or drying items at tempertures >130 degrees F will kill stray lice or nits.
(3) Furniture, carpet, car seats, etc should be vacuumed.
(4) Although rarely necessary, items that cannot be washed can be bagged for 2 weeks – long enough for any nits to hatch and then die of starvation!
(5) IT IS NOT NECESSARY TO PROMOTE A FULL HOME REMODLE in order to rid the house of the louse!

Frankowski BL, Bocchini JA, Council on School Health and Committee on Infectious Diseases. Head Lice. Pediatrics: Vol. 126(2); Aug. 1, 2010. Pp.392-403.


Sean M. Fox
Sean M. Fox
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