BY RICK VOAKES, MD
What To Do About Headlice
Headlice is a common school-acquired problem. Once lice get established in the hair, it can be very challenging to get them out. Most common insecticides are no longer effective in killing them. Just like resistant bacteria, the "resistant" headlice are the ones who live on and have more lice-babies who are resistant just like their parents.
Headlice lay eggs, called nits, on the hair shaft. They are attached so strongly, the only way to get them off is to slide them off the end of each hair shaft. Use your fingernail against your thumb while holding the hairshaft with your other hand. Once removed, they can be dropped on the floor where they will die in a few days. Lice live off your blood, and must be close to the scalp to get more blood for food. Headlice cannot fly or jump, so they are spread only by direct contact with hair or shared caps or combs.
Most nits are laid close to the scalp, so look there first, especially around the ears and nape of the neck. They look like tiny oval grains of sand, firmly attached to the hair. If they fall off, they are not nits. The adult lice look like tiny furry brown or beige bugs. They crawl through the hair quickly, and come in various sizes.
The most important part of treatment is getting all the nits out, which means 100% of them! I usually treat with an insecticide the first time, then work hard on removing all the nits. A magnifying glass can be helpful, and be sure to have good light. If bugs come back, they might be resistant to the insecticide, but is often a re-infestation from school, or just not getting 100% of the nits out.
Nix (permethrin) is usually about 90-95% effective in killing lice, while the other over-the-counter products are generally less effective, in the 50-75% range. A new prescription insecticide called Ovide contains malathione, and is also quite effective. Ulesfia is a less toxic new treatment.
An interesting article a few years ago, tested several toxic substances on nits, including insecticides, WD-40, oven cleaner, hydrochloric acid, among others. Nothing killed them, and the hydrochloric acid dissolved the hair, and left the nits to hatch into healthy new lice.
Another often used treatment is putting mayonaise on the hair for 3-4 hours, holding it on with a plastic shower cap. Then rinse it out and start working on the nits. The mayonaise suffocates the live bugs, and softens the nits, making it easier to remove them. But it does not kill the nits! Vaseline can also be used, but is much more difficult to remove from the hair. Mayonaise is high in protein and is a good hair conditioner.