Medications

There are both over-the-counter medicines and prescription products to treat head and pubic lice. Most products come as a shampoo, creme rinse, or lotion (topical treatment) that is applied to the affected areas, left on for a period of time, and then rinsed off. Doctors sometimes prescribe the pill ivermectin to treat lice when two or more approved topical medicines have not been effective.

Permethrin 1% creme rinse (such as Nix) is a common first method of treating lice because it is safe and effective and continues to kill lice and their eggs (nits) even after the cream has been rinsed off. This product is available without a prescription.

When treating lice with medicine, keep in mind:

• A second treatment 7 to 10 days after the first treatment is usually recommended to ensure that any newly hatched lice are also killed.
• Itching may persist even after successful treatment. Do not reapply medicated products unless you are advised to do so by a doctor. Excess use of these products may increase the risk of negative side effects such as nausea, headaches, or more serious side effects.

If lice infest the eyelashes, applying petroleum jelly (such as Vaseline) to the eyelashes several times a day for a week can kill the lice.

In general, drugs are not needed to treat body lice—since the lice live in clothing, not on the body—unless the person is severely infested. The most common way to kill body lice and eggs is to wash clothing and bedding in hot water [130°F (54.44°C) or higher] in an automatic washing machine.

Medication Choices

Over-the-counter products for head and pubic lice

• Permethrin creme rinse 1% (Nix) is a common first choice for treating head lice. It kills lice and their eggs for 2 weeks or more after it has been rinsed off.
• Shampoos containing pyrethrins and piperonyl butoxide (Pronto, Rid, A-200) are left on the hair for 10 minutes and then rinsed out. A second treatment is needed 1 week after the first to kill newly hatched lice.

These over-the-counter products are not meant for children younger than age 2.

Prescription products for head and pubic lice

• Permethrin cream 5% (Elimite) is a cream that is applied to the skin or scalp, left on for 8 to 14 hours, and then rinsed off.
• Malathion lotion (Ovide) is applied to hair, left on for 8 to 12 hours, then rinsed off. If lice are still present 7 to 9 days later, a second treatment must be done.
• Lindane (Kwell, G-Well) is a lotion or a shampoo that should only be used when other products fail to get rid of lice or when a person cannot use any of the other products. Lindane contains potentially harmful toxins that can cause negative side effects when it is not used properly.⁴

A pill called ivermectin is sometimes prescribed to treat lice when the person does not respond to two or more topical treatments (treatments applied directly to the affected area).⁵

Antihistamines (both prescription and nonprescription) can treat the itching that often occurs with lice. These medicines may cause drowsiness. Don't give antihistamines to your child unless you've checked with the doctor first.

If there is a serious skin infection, antibiotics may be needed.

Prescription medicines such as thiabendazole, crotamiton, or trimethoprim sulfamethoxazole (Bactrim, Septra) are sometimes used to treat head and pubic lice.⁶

What To Think About

It is not necessary to remove lice eggs from hair after treatment with topical medicines, but some people may wish to remove them for cosmetic reasons.

Most products used to treat lice may cause side effects if they are not used properly. Never use a product more than two times (with less than 7 days between uses) without first consulting a doctor.

There is some concern that lice are becoming resistant to (can no longer be killed by) permethrin or other medicine used to treat lice infestations. It is also possible that lice may persist after treatment because the medicine was not used properly or because the person was reinfected by someone else who was still infected with lice.

In cases where multiple treatments have failed to get rid of lice or where resistance is suspected, some doctors are prescribing combinations of treatments, such as permethrin cream along with trimethoprim sulfamethoxazole (Bactrim, Septra).