Permethrin for Lice

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Permethrin for Lice


Permethrin is available in both nonprescription and prescription strengths.

Generic NameBrand Name
permethrin 1%Nix
permethrin 5% Elimite

Permethrin 1% (such as Nix) is a nonprescription creme rinse used to treat lice. Here are general instructions for treating head lice:

  • Wash and towel-dry the hair. Do not use any hair conditioner.
  • Apply enough of the nonprescription creme rinse to the hair to saturate the hair and scalp.
  • Leave the creme rinse on for 10 minutes.
  • Rinse the creme rinse off with water.
  • Avoid getting permethrin in the eyes. Although the product is not known to be harmful to the eyes, rinse the eyes well with water if the creme rinse gets into them.

Some doctors advise a second treatment 7 to 10 days after the first treatment if a person still has live lice on himself or herself.

Permethrin 5% (Elimite) is a prescription cream that is applied to the skin or hair, left on for 8 to 14 hours, and then rinsed off.

How It Works

Permethrin kills lice and, in many cases, their eggs (nits). Permethrin continues to kill lice and eggs for at least 2 weeks after it has been rinsed off.

Why It Is Used

Nonprescription permethrin creme rinse (such as Nix) is a common first choice for treating head lice.

Elimite may be used to treat cases of lice that persist after treatment with other nonprescription products.

How Well It Works

Permethrin is very safe and effective. But resistance to permethrin has been reported in many countries (such as the United Kingdom and the United States). If resistance to permethrin is noted, your doctor can recommend other treatment (such as malathion or pyrethrin).

Side Effects

All medicines have side effects. But many people don't feel the side effects, or they are able to deal with them. Ask your pharmacist about the side effects of each medicine you take. Side effects are also listed in the information that comes with your medicine.

Here are some important things to think about:

  • Usually the benefits of the medicine are more important than any minor side effects.
  • Side effects may go away after you take the medicine for a while.
  • If side effects still bother you and you wonder if you should keep taking the medicine, call your doctor. He or she may be able to lower your dose or change your medicine. Do not suddenly quit taking your medicine unless your doctor tells you to.

Call 911 or other emergency services right away if you or your child has:

  • Trouble breathing.
  • Swelling of the face, lips, tongue, or throat.

Call your doctor if you or your child has:

  • Hives.

Side effects of this medicine include:

  • Burning, stinging, or tingling.
  • Itching.
  • Skin redness or rash.
  • Numbness.

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

What To Think About

Itching may last for 7 to 10 days after treatment. But itching is not a reason to use the product again. Overuse of lice products (such as using the product twice when only a single use is prescribed) can irritate the skin and may increase the risk of side effects.

Taking medicine

Medicine is one of the many tools your doctor has to treat a health problem. Taking medicine as your doctor suggests will improve your health and may prevent future problems. If you don't take your medicines properly, you may be putting your health (and perhaps your life) at risk.

There are many reasons why people have trouble taking their medicine. But in most cases, there is something you can do. For suggestions on how to work around common problems, see the topic Taking Medicines as Prescribed.

Advice for women

If you are pregnant, breast-feeding, or planning to get pregnant, do not use any medicines unless your doctor tells you to. Some medicines can harm your baby. This includes prescription and over-the-counter medicines, vitamins, herbs, and supplements. And make sure that all your doctors know that you are pregnant, breast-feeding, or planning to get pregnant.


Follow-up care is a key part of your treatment and safety. Be sure to make and go to all appointments, and call your doctor if you are having problems. It's also a good idea to know your test results and keep a list of the medicines you take.

Complete the new medication information form (PDF)(What is a PDF document?) to help you understand this medication.


ByHealthwise Staff
Primary Medical ReviewerJohn Pope, MD - Pediatrics
Specialist Medical ReviewerSusan C. Kim, MD - Pediatrics
Last RevisedAugust 30, 2012

Last Revised: August 30, 2012

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