Treatment

Your doctor will likely recommend an over-the-counter (OTC) medication that kills lice and some of the nits. These medications may not kill recently laid eggs. Therefore, an appropriately timed second treatment is usually necessary to kill nymphs after they hatch but before they become adult lice.

Some studies suggest that retreating seven to nine days after the first treatment is the ideal time for a second treatment, but other retreatment schedules exist. Ask your doctor for written instructions for a recommended treatment schedule.

Over-the-counter (OTC) products

OTC medications are based on pyrethrin, a chemical compound extracted from the chrysanthemum flower that is toxic to lice. Wash your child's hair with shampoo with no conditioner before using one of these treatments. Rinsing the hair with white vinegar before washing may help dissolve the glue that holds the nits to the hair shafts. Follow directions on the package for how long to leave the medication in the hair, and rinse your child's hair over a sink with warm water.

OTC medications include the following:

• Permethrin (Nix). Permethrin is a synthetic version of pyrethrin. Permethrin does not kill nits, and treatment needs to be repeated nine to 10 days after first application. Side effects may include redness and itching of the scalp.
• Pyrethrin with additives (Rid). In this OTC medication, pyrethrin is combined with another chemical that enhances its effectiveness. This product only kills lice, not nits, and needs to be reapplied nine to 10 days after first treatment. Side effects may include itching and redness of the scalp. Pyrethrin shouldn't be used if your child is allergic to chrysanthemum or ragweed.

Prescription medications

In some geographic regions, lice have developed resistance to OTC medications. Also, OTC treatment may fail because of incorrect use, such as not repeating the treatment at an appropriate time.

If the correct use of an OTC treatment has failed, your doctor may recommend a prescription treatment. These include:

• Ivermectin (Sklice). Ivermectin is toxic to lice. It is approved for use with people age 6 months or older. It can be applied once to dry hair and then rinsed with water after 10 minutes. Ivermectin is also available as a tablet to be taken by mouth to children weighing more than 33 lbs. if other topical treatments do not effectively eliminate a lice infestation.
• Spinosad (Natroba). Spinosad is approved for use with people age 6 months or older. It can be applied to dry hair and rinsed with warm water after 10 minutes. It kills lice and nits and usually doesn't need repeated treatment.
• Malathion. Malathion is approved for use with people age 6 or older. The lotion is applied, left to dry naturally and rinsed out after eight to 12 hours. The drug has a high alcohol content, so it can't be used with a hair dryer or near an open flame. Malathion can be reapplied seven to nine days after the first treatment if necessary.