Treatments and drugs

By Mayo Clinic Staff

Your doctor will likely recommend an over-the-counter (OTC) medication that kills lice and some of the eggs. 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 the ninth day 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.

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. Side effects may include redness and itching of scalp.
  • Pyrethrin with additives (Rid, A-200 Lice Killing). In this OTC medication, pyrethrin is combined with another chemical that enhances its toxicity. 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:

  • Benzyl alcohol (Ulesfia). This product is not toxic to lice but kills them by depriving them of oxygen. Side effects may include redness and itching of the scalp. The use of benzyl alcohol to disinfect medical devices has been shown to cause seizures and other severe reactions in newborn infants. Therefore, lice treatment with benzyl alcohol is not approved for use in children less than 6 months of age.
  • Malathion (Ovide). Malathion is approved for use with people age 6 or older. The medicated shampoo 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.
  • Lindane. This medicated shampoo has a risk of severe side effects, including seizures, and is used only when other treatments have failed. It is not recommended by the American Academy of Pediatrics for use on children. The Food and Drug Administration (FDA) warns that it should not be used on anyone who weighs less than 110 pounds (50 kilograms), is pregnant or breast-feeding, has a history of seizures, or has HIV infection.
Jun. 18, 2014

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