There is a good website on this topic at


Lice are blood-sucking insects. They are gray bugs that are about 1/16 of an inch long and move really quickly.


The life cycle of lice is important to know so that we can understand why we treat them the way that we do. The female adult louse lives on the scalp and lays eggs at the base of hair shafts. They may lay 7 to 10 eggs per day, which hatch approximately 8 to 10 days later. These eggs are cemented to the hair in egg casings (nits)  and unlike dandruff, sand, mousse and other hair products, the nits can’t be shaken from hair shafts. . Eggs that have hatched are white, whereas newly formed nits are brown. Nymphs emerge from hatched eggs and mature into the adult form over a period of 8 to 15 days


They are transmitted by hair-to-hair contact and by fomites (e.g., hair accessories, hairstyling tools, and clothing). Hygiene does not seem to have a role in getting the lice, in fact, cleaner hair is easier to infect than dirty hair.


Clinical Features

The kids usually have an itchy scalp, and the lymph nodes on the back of the neck may swell.  Pus, open scabs and sores on the scalp are not part of the infection and should be evaluated in the office.



The treatment takes advantage of the life cycle of the louse.  So remember, the louse is blood-sucking.  That means, in order to get its food to stay alive, the lice have to be within reach of the source of blood, the scalp.  Anything more than 5mm away from the scalp has no source of food and is NOT alive and therefore does not need to be treated. 


We use a lice shampoo to try to treat living lice.  None of the available treatments completely kill all the eggs, so a repeat application 1 week (and no sooner!) following the initial application is really important.  The eggs take a week to hatch so daily treatment is NOT necessary and can really irritate the scalp. This is not a problem we see in the office, but the home part isn’t too hard.


How to Use Lice Shampoo


1.     Buy Nix 1% anti-lice crème rinse (This is over the counter)


2.     Pour 2 ounces of the shampoo into dry hair. Add a little water and work up into a lather.  Be sure to work the shampoo into all the hair down to the roots.  Leave it on for TWENTY minutes. Note: The box may say to leave it on for ten minutes, but I recommend you leave it on for 20! Then rinse and dry.


3.     Don’t use any crème rinse shampoos or conditioner during the treatment time (that would be a two-week period) because it coats the hair shaft and the medication doesn’t work as effectively.


4.     Do it again in a week.



Now comes the hard part: nit removal (nit-picking!). Wait 3 or more hours after the NIX treatment is completed and then loosen the nits from the hair shafts using half vinegar and half water applied for 30 minutes under a towel wrap.   Then backcomb them out or get them one by one.  I’ve heard about a device called a LiceMeister that works for nit removal as well.  (See


If the Nix doesn’t work, you can try olive oil or mayonnaise.  The idea is to smother the lice.  The mayo must be the full fat option (no dieting for these guys!)


If you use olive oil/mayo then apply it at bedtime, cover the hair with a shower cap and leave it this way for 8 hours,   Then try combing out the nits in the morning, BEFORE you wash the hair.


Preventing Repeat Infection


1.     Check everybody in the house and treat them too.

2.     Notify the school nurse or day care center director so they can check the other children for infection—the most common reason for treatment not to work is re-infection. 

3.     Vacuum everything.

4.     Soak combs and brushes for 1 hour in a solution containing anti-lice shampoo.

5.     Wash anything your child has worn for the past 3 days and all blankets, pillows and such in really hot water (140 degrees) and if you can’t wash it, stuff it.  In a sealed bag that is, for 2 weeks.