How does this medication work? What will it do for me?

Permethrin 1% belongs to a group of medications called synthetic pyrethroids, which are insecticides. Permethrin 1% works by paralyzing lice, killing them and their nits (eggs). This product works to get rid of lice infestation. Scalp itching may continue for up to 2 weeks after treatment.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are using this medication, speak to your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to use this medication if their doctor or pharmacist has not recommended it.

What form(s) does this medication come in?

Each g of crème rinse contains: permethrin 1% w/w. Nonmedicinal ingredients: balsam Canada, cetyl alcohol, citric acid, FD&C Yellow No. 6, hydrolyzed animal protein, hydroxyethylcellulose, isopropyl alcohol, methylparaben, perfume, polyoxyethylene 10 cetyl ether, propylene glycol, propylparaben, stearalkonium chloride, and water.

How should I use this medication?

Before using this product, wash your hair with conditioner-free shampoo; rinse it, and towel-dry.

Shake the bottle well. Apply enough of the product to ensure that the hair and scalp are completely covered, especially behind the ears and at the base of the neck. Typically, 25 mL to 50 mL is needed. Keep it in your hair for 10 minutes and then rinse with water. Comb your hair with a regular comb to remove tangles. Then, separate a strand of hair no wider than the nit comb and remove nits using the nit comb. Wipe off the comb and repeat until all the hair has been combed with the nit comb. Check the hair and remove nits daily for 7 days after treatment.

Do not apply permethrin cream rinse to mucous membranes (inside of mouth, nose) or near the eyes.

It is unlikely that you will need a second application. However, if you observe lice 7 days after the first treatment, repeat the process again.

Since lice infestations are spread through contact, you should make sure that your family members and sexual partner(s) are examined for lice infestation. If they are infested, they should speak to their doctor or pharmacist immediately about using this product. Also notify your child's school, daycare, or other people who have been in close contact.

To prevent reinfestation, contaminated items such as bedding, clothing, towels, and hats should be washed in hot water and dried in the dryer using the hot cycle for at least 20 minutes. If items cannot be washed and dried this way, dry-clean or seal them in a plastic bag for 2 weeks and wash normally. Combs and brushes should be soaked in hot water above 54°C or in undiluted product for 5 to 10 minutes and rinsed with hot water.

If your doctor or pharmacist has recommended a dose different from the ones listed here, do not change the way that you are using the medication without consulting your doctor. It is important that this medication be used exactly as recommended by your doctor or pharmacist.

Store this medication at room temperature and keep it out of the reach of children.

Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.

Who should NOT take this medication?

Permethrin 1% should not be used by anyone who is allergic or sensitive to permethrin, any synthetic pyrethroid or pyrethrins, ragweed, chrysanthemums, or to any of the ingredients of the medication.

What side effects are possible with this medication?

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is used in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who uses this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

  • itching
  • mild burning or stinging
  • redness, numbness, tingling or rash of the scalp

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Are there any other precautions or warnings for this medication?

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Accidental swallowing: If permethrin cream rinse is swallowed, consult your doctor or a poison control centre immediately.

Eye irritation: If this product gets into your eyes, rinse with clear water immediately to minimize eye irritation.

Pregnancy: This product should not be used during pregnancy unless the benefits outweigh the risks. Talk to your doctor or pharmacist before using this product.

Breast-feeding: It is not known if permethrin passes into the breast milk. If you are a breast-feeding mother and are using this medication, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of using this medication have not been established for children less than 2 years of age.

What other drugs could interact with this medication?

Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications that you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them. Depending on your specific circumstances, your doctor may want you to:

  • stop taking one of the medications,
  • change one of the medications to another,
  • change how you are taking one or both of the medications, or
  • leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. In many cases, interactions are intended or are managed by close monitoring. Speak to your doctor about how any drug interactions are being managed or should be managed.