Nix (Permethrin 1%) - Topical

What Is Nix?

Nix (permethrin 1%) treats head lice (Pediculus humanus capitis). It is an over-the-counter (OTC), topical pediculicide medicine (kills pests on skin and hair). 

Nix works by preventing sodium (salt) from entering the cells of head lice, leading to their paralysis and death.

Nix is available as a solution, shampoo, creme rinse, and spray.

Drug Facts

Generic Name: Permethrin 1%

Brand Name(s): Nix

Administration Route(s): Topical

Drug Availability: Over the counter (OTC)

Therapeutic Classification: Pediculicide

Available Generically: Yes

Controlled Substance: N/A

Active Ingredient: Permethrin

Dosage Form(s): Cream, liquid, lotion

What Is Nix Used For?

According to a review of U.S. consensus guidelines, permethrin 1% lotion or shampoo (Nix) is suggested as a first-choice medication to treat head lice. Permethrin 5% strength is typically used to treat scabies

Head lice are common in preschool and elementary school-age children. In the United States, the Centers for Disease Control and Prevention (CDC) estimates that about 6 million to 12 million cases of head lice occur every year in children between 3 and 11 years old.

Nix (Permethrin 1%) Drug Information - Illustration by Zoe Hansen

Verywell / Zoe Hansen

How to Use Nix

Since directions might vary for each OTC product and formulation, carefully read the labeling and the information on the package or container. In general, don’t use Nix products near the eyes, eyebrows, eyelashes, mouth, nose, or vagina. The following are typical steps to use Nix:

Nix Ultra Solution or Nix Shampoo 

  1. Before using, make sure to remove nearby hot objects. Don’t use Nix Solution or Nix Shampoo near open fire or flames. Don’t smoke when using this product. 
  2. Completely cover dry hair and scalp with Nix Solution or Nix Shampoo product. Make sure to use Nix behind the ears and at the nape (back of the neck).
  3. Leave the solution or shampoo in the hair for only 10 minutes. Don’t cover up the hair, such as with a cap or wrapped foil.
  4. Protect the eyes with a towel.
  5. Thoroughly wash the hair.
  6. If using Nix Solution, thoroughly wash hair with regular shampoo. Don’t use conditioner or shampoo that has conditioner. 
  7. If you’re using Nix Shampoo, however, you don’t need to use more regular shampoo. After rubbing some water into the hair to create a lather or foam, rinse out the foam with warm—not hot—water. Hot water may increase permethrin’s absorption through the skin. Rinse over a sink instead of in the shower or bath, if possible. If necessary, for long or curly hair with tangles, you may use conditioner.
  8. Dry hair with a towel but keep hair damp.
  9. Part hair into four sections.
  10. Start at the top of the head.
  11. Remove lice and nits (eggs) by combing through 1–2 inches of hair at a time in each section. Place the teeth of the fine-tooth comb close to the scalp and use a firm and even motion from the scalp to the end of the hair.
  12. Use clips to pin back each section of combed hair.
  13. Repeat steps 10 and 11 for additional sections.
  14. Every now and then, clean your comb by wiping lice and nits onto a clean tissue or a dry paper towel.
  15. Place the used tissue or paper towel in a sealable bag before sealing and throwing it in the trash.
  16. After combing through all four sections of hair, recheck the entire head for missed lice or nits.
  17. Don’t rewash hair for another one to two days after using the Nix product.
  18. Check hair again in seven days. If lice and nits are still present, repeat steps 1–17.

Nix Creme Rinse

  1. Wash hair with regular shampoo. Don’t use conditioner or shampoo that has conditioner.
  2. Use a towel to dry hair. Hair should be damp but not too wet.
  3. Shake the bottle of Nix Creme Rinse before completely covering the hair and scalp with the product. Make sure to use the creme rinse behind the ears and at the nape.
  4. Protect eyes with a towel.
  5. Leave the creme rinse in the hair for only 10 minutes. Don’t cover up the hair, such as with a cap or wrapped foil. After 10 minutes, rinse hair with warm—not hot—water. Hot water may increase permethrin’s absorption through the skin. Rinse over a sink instead of in the shower or bath, if possible. 
  6. Dry hair with a towel.
  7. Part hair into four sections.
  8. Follow steps 11–18 of the directions for Nix Ultra Solution or Nix Shampoo above.

Nix Lice Killing Spray

  1. Wash the following items in hot water—at least 130 degrees—before drying them in the dryer on the hottest cycle for a minimum of 20 minutes: hats, hair ribbons and any other items that are worn in the hair, scarves, coats, towels, or bed linens.
  2. Soak personal brushes and combs—including nit combs—in hot water that is at least 130 degrees.
  3. Vacuum all carpets, mattresses, soft-padded furniture, and car seats. Throw away vacuum bags in trash.
  4. For items that cannot be washed (including certain clothes, blankets, pillows or stuffed animals), use one of the following options: A) Dry-clean. B) Place items in tightly sealed plastic bags. After two weeks, remove and shake items outside before using again. C) Use Nix Lice Killing Spray. More detailed directions in step 5 below.
  5. For some items mentioned in step 4, you may use Nix Lice Killing Spray with the following directions:
  • Before spraying, wear a long-sleeve shirt, long pants, socks, shoes, and a mask, if possible.
  • Before spraying, remove all food and cooking utensils. If utensils were not removed, wash them after spraying.
  • Cover all food-handling surfaces—like dining tables and kitchen islands—before spraying.
  • Shake the spray bottle well.
  • Spray on a small area of the item—like the bedding—to test for potential staining or discoloration.
  • After the spray dries on the item, inspect the test spot before spraying the entire item from a distance of 8–10 inches away. 
  • Permethrin can be toxic to animals, plants, and living things in waterways. Avoid spraying it into drains or gutters that will lead into sewers and large bodies of water. 
  • Wait until all sprayed items are dry before allowing people and pets to reenter the house and reuse the items.
  • If the spray gets onto your clothes, immediately remove and wash clothes, and change into clean clothes, if available.
  • After you are done spraying, make sure to wash your hands before eating, drinking, chewing gum, smoking, or using the toilet.

Storage

Since Nix is available as an OTC product, you can usually buy this item without a prescription. After bringing Nix home, store it at room temperature, between 68 degrees and 77 degrees. Keep the bottle standing upright.

If you are planning to travel with Nix, take time to familiarize yourself with the regulations of your final destination. In general, however, keep Nix in its original container and packaging.

Off-Label Uses

The CDC recommends the off-label use of Nix Creme Rinse as an alternative treatment option for pubic lice (Pediculosis pubis).

How Long Does Nix Take to Work?

After eight to 12 hours of using Nix, you should notice that the medication is starting to work. You may still notice a few slow-moving live lice. If so, use a nit comb to remove any dead and remaining live lice from hair. 

If you find no dead lice and only normal-moving live lice after eight to 12 hours of using Nix, then notify a healthcare provider to discuss next steps.

What Are the Side Effects of Nix?

Although Nix is an OTC product, side effects are possible with this medication.

This is not a complete list of side effects and others may occur. A medical professional can advise you on side effects. If you experience other effects, contact your pharmacist or a medical professional. You may report side effects to the FDA at www.fda.gov/medwatch or 800-FDA-1088.

Common Side Effects

Common side effects are usually limited to the scalp and may include:

  • Itching
  • Redness

Severe Side Effects

If you experience the following serious side effects, seek immediate medical attention.

  • Breathing difficulties
  • Eye irritation
  • Infection
  • Skin or scalp irritation that doesn’t go away

Long-Term Side Effects

If used as the labeling or packaging instructions recommend, Nix can be safe and nontoxic, even with a second treatment.

Using Nix too many times, however, may lead to resistant lice. This means Nix may no longer work on or treat the head lice.,

Report Side Effects

Nix may cause other side effects. Call your healthcare provider if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your provider may send a report to the FDA's MedWatch Adverse Event Reporting Program or by phone (800-332-1088).

Dosage: How Much Nix Should I Take?

Drug Content Provided and Reviewed by IBM Micromedex®

The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

  • For topical dosage forms (cream and lotion):
    • For head lice:
      • Adults and children 2 years of age and older—Apply to the hair and scalp one time.
      • Children up to 2 years of age—Use and dose must be determined by your doctor.
    • For scabies:
      • Adults and children 2 months of age and older—Apply to the skin one time.
      • Children up to 2 months of age—Use and dose must be determined by your doctor.

Modifications

Children

Some Nix products shouldn’t be used on children at certain ages, including:

  • Nix Ultra Solution is not recommended for children younger than 2 years old.
  • Nix Ultra Shampoo is not advised for infants younger than 12 months of age.
  • Nix Creme Rinse should not be used in infants under 2 months of age.

Pregnant or Nursing Parents

While CDC has authorized permethrin to be used during pregnancy or nursing,9 speak with a healthcare provider first. Ask any questions and bring up any concerns you may have before using the product. Studies suggest that nursing parents may use permethrin products designed to be used on the skin.

Missed Dose

Nix products are typically used one time. After the first use, some people may need to use the medication again after seven days. If this second treatment is necessary and you missed it, then you or your child will likely still have live head lice.

If you still notice live head lice after two uses of Nix, get in touch with a healthcare provider to discuss next steps.

Overdose: What Happens If I Use Too Much Nix?

If you use Nix too much, the head lice may become resistant to the medication, meaning it will no longer work as well. If you or your child still have live lice after two uses of Nix, inform your healthcare provider.,

You or your child should never drink Nix to treat head lice. If you or your child accidentally drank Nix, seek immediate medical attention or call the Poison Control Center at 800-222-1222.

What Happens If I Use Too Much Nix?

If you think you or someone else may have overdosed on Nix, call a healthcare provider or the Poison Control Center (800-222-1222).

If someone collapses or isn't breathing after taking Nix, call 911 immediately.

Precautions

Drug Content Provided and Reviewed by IBM Micromedex®

To prevent reinfection or spreading of the infection to other people, good health habits are required. These include the following:

  • Machine wash all clothing (including hats, scarves, and coats), bedding, towels, and washcloths in very hot water and dry them by using the hot cycle of a dryer for at least 20 minutes. Clothing or bedding that cannot be washed should be dry cleaned or sealed in an airtight plastic bag for 2 weeks.
  • Shampoo all wigs and hairpieces.
  • Wash all hairbrushes and combs in very hot soapy water (above 130 °F) for 5 to 10 minutes and do not share them with other people.
  • Clean the house or room by thoroughly vacuuming upholstered furniture, rugs, and floors.
  • Wash all toys in very hot soapy water (above 130 °F) for 5 to 10 minutes or seal in an airtight plastic bag for 2 weeks. This is especially important for stuffed toys used on the bed.

What Are Reasons I Shouldn’t Use Nix?

If the following applies to you or a child in your care, talk to a healthcare provider before using Nix:

  • Children: If the child is younger than 2 years old, please carefully check the Nix container and packaging instructions. The manufacturer does not recommend certain Nix products on children under a certain age.
  • Irritated or injured scalp: If the scalp is already irritated or injured, don’t use Nix.
  • Mineral oil allergy: If there is an allergy to mineral oil, Nix Ultra Shampoo and solution are not recommended.
  • Pubic lice: If pubic lice are present, talk with a healthcare provider.
  • Ragweed allergy: If the person using Nix has a ragweed allergy, Nix Creme Rinse may not be the best Nix product.
  • Silicone allergy: If a silicone allergy is present, don’t use Nix Ultra Solution.

What Other Medications Interact With Nix

Drug interactions between Nix and other medications are lacking.

What Medications Are Similar?

In addition to Nix, there are other medications used to treat lice. The following are other topical over-the-counter (OTC) products that treat lice:

  • Pyrethrin/piperonyl butoxide: Pyrethrin/piperonyl butoxide is commonly known as RID Shampoo or LiceMD Gel. This combination medication may also be available as A-200 or Pronto. If used appropriately, this OTC product works. Due to resistance, however, it is not as effective against head lice. Additionally, if you, your child, or other family member has a chrysanthemum or ragweed allergy, avoid this combo product. Pyrethrin-based medications are also not recommended in children under 2 years old. 
  • Ivermectin: Ivermectin lotion goes by the brand-name Sklice. It can be used in children who are at least 6 months old. Sklice is effective for many people after a single use of the lotion on dry hair without nit-combing, but nit-combing raises the chance of success. This medication may also prevent newly hatched lice from surviving. It shouldn’t be used more than once, however, without discussing with a healthcare provider.,

Compared to other topical OTC medications, Nix Creme Rinse can be used in infants as young as 2 months of age and older. Additionally, U.S. guidelines suggest permethrin 1% lotion or shampoo (Nix) as a first-choice treatment for head lice.

Since each of these topical products are used to treat head lice, they are usually not used together. If you have any questions, please talk with a healthcare provider or pharmacist.

Frequently Asked Questions

  • Are head lice due to poor hygiene?

    No, head lice are not due to poor hygiene.

  • Can I prevent head lice with frequent hair brushing or shampooing?

    The amount brushing or shampooing isn’t linked to a higher or lower likelihood of head lice.

  • Can head lice spread disease?

    No, head lice do not spread disease.

  • Can pets spread head lice?

    No, pets don’t spread head lice.

  • How long can head lice survive away from the scalp?

    Head lice can only live for one to two days away from the scalp. Their eggs cannot hatch at temperatures below scalp temperatures.

  • Why is a nit comb necessary?

    Experts recommend a fine-toothed comb to effectively remove head lice.

How Can I Stay Healthy While Using Nix?

While head lice don’t spread disease, they can be the cause of anxiety for adults who get head lice, children who get head lice, and children’s guardians. Many people may also experience worsening anxiety due to misinformation and myths surrounding head lice.

To lessen your anxiety, learn more about head lice to feel more in control, to understand how to get rid of lice, and to prevent these pests from becoming resistant to treatment options. If you have questions on how to use Nix, talk with a healthcare provider or pharmacist. 

Due to the negative stigma surrounding head lice, many people tend to keep quiet about it. If you discover that your child has head lice, however, notify your child’s daycare and school nurse to stop the spread of these pests.

Work with the school to prevent children from missing too many days of school. Also, teach your child about habits to limit head-to-head contact. For example, encourage your child to not share combs, brushes, hair ribbons, hats, and helmets.

Since effective treatment options with nit-combing exist to get rid of head lice, don’t immediately resort to shaving your child’s head. Experts don’t recommend shaving a child’s head because it can be traumatic for the child. Instead, find ways to help the child relax and put things in a positive light.

Medical Disclaimer

Verywell Health's drug information is meant for educational purposes only and is not intended as a replacement for medical advice, diagnosis, or treatment from a healthcare professional. Consult your doctor before taking any new medication(s). IBM Watson Micromedex provides some of the drug content, as indicated on the page.

9 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Gunning K, Kiraly B, Pippitt K. Lice and scabies: treatment update.

  2. PDR. Permethrin - Drug Summary.

  3. CDER. Approval Package for Nix Cream Rinse.

  4. CDC. Parasites: Epidemiology & Risk Factors.

  5. Devore CD, Schutze GE, Okamoto J, et al. Head Lice.

  6. CDC. Parasites: Treatment.

  7. US EPA. Permethrin Facts (Reregistration Eligibility Decision (RED) Fact Sheet).

  8. CDC. Sexually Transmitted Diseases Treatment Guidelines.

  9. National Library of Medicine (US). Drugs and Lactation Database (LactMed): Permethrin.

By Ross Phan, PharmD, BCACP, BCGP, BCPS
Ross is a writer for Verywell with years of experience practicing pharmacy in various settings. She is also a board-certified clinical pharmacist and the founder of Off Script Consults.