How to Kill Lice and Nits Using Insecticidal Shampoo

Through the centuries, treatment of lice has consisted of everything from shaving a person’s head to rubbing mixtures of garlic, olive oil and vinegar on the scalp. Today, however, the common treatment involves using a special shampoo, usually with a lindane base.

Lindane is a pesticide that will kill all adult and immature lice, and most of the nits. If available, parents’ choice for children’s first treatment probably should be either Nix cream rinse (1 percent permethrin) or Ovide lotion (0.5 percent malathion), which smells but also will kill many eggs, as well as adult lice.

The follow-up treatment can be either one of those products or an over-the-counter pyrethrin or resmethrin product. New anti-lice products are effective and fairly easy to use. Doctors recommend a prescription product to be used according to directions.

How to Use Anti-Louse Shampoo 

If you’re infested, you’ll need a louse-killing insecticide shampoo to rid yourself of them. These are available at drug stores. Your family physician may prescribe one, or you may receive the names of these products from your school nurse or public health clinic.

Most drug stores have two or three brands in lotion, cream, gel or shampoo form. It is important in treatment to follow the directions closely and continue the treatment for the prescribed time. Pediculicides (louse killers) are safe products unless used too often or too heavily. If one product doesn’t seem to be working, the solution is to wait a week and try another formulation, not over-apply the one you have.

Remember, you’re dealing not only with lice but their eggs as well. Dead nits may be removed from the hair with a fine comb following proper treatment, which dissolves the tough cement binding the nit to the hair.

Lice Shampoos Containing Pyrethrin

The active ingredient in anti-louse shampoos and body lotions are based on naturally occurring substances called pyrethrins. The shampoo or lotion can be purchased without a prescription at most pharmacies. Over-the-counter medications, most containing pyrethrin, a derivative of chrysanthemums, are available in several strengths.

RID and Triple-X, which are twice as strong as A-200, all contain pyrethrins. The milder solution of A-200 may be advised for a young child or a very minor infestation. Cuprex is a product with a different active ingredient, tetrahydronaphthalene, a derivative of naptha, the basis of mothballs. Prioderm contains a. 5 solution of malathion, a well-known and effective pesticide. 

If used in the amounts recommended, it takes approximately two ounces of the pyrethrin products to treat one person. Many of the products cost around $5 for the amount needed to treat one person.

Lice Shampoos Containing Lindane 

Kwell is a prescription-only shampoo containing lindane, a pesticide being reviewed by the Environmental Protection Agency for the uses under its jurisdiction. Doctors don’t recommend that pregnant women or children under 2 years of age use Kwell shampoo. It is a pesticide, and it has to be harsh to be effective – but it is safe.

According to the EPA, lindane causes cancer in mice and is absorbed readily through the skin. It may be hazardous for pregnant women. The EPA is proposing restriction of its use, including eliminating it from dog shampoo. There also are some strains of lice resistant to lindane.

Some doctors had patients with neurological problems from lindane. In small children, it can be absorbed through the skin. Problems can arise because some parents think if a little bit is good, a lot is better.

Does Lice Shampoo Kill Nits, Too? 

Anti-louse medications are highly effective against living lice, but less effective against nits. Because of this, re-treatment in 7-10 days is recommended to kill any newly hatched lice that might have escaped the first round of treatment.

The second treatment is very effective in killing any newly hatched lice before they can get a chance to lay eggs and continue the infestation. Failing to treat a second time may result in persistence of infestation. A third treatment is not necessary.

For those nits that are close to the scalp, persons should use insecticidal cream rinse and a fine tooth comb. Nits remaining after the combing should be removed one at a time with tweezers. School-aged children can return to school immediately after the first treatment.