What is Permethrin? Uses, warnings & side effects

Follow the doctor’s directions and the medicine label when using prescription permethrin.

If using permethrin without a prescription, read and follow the instructions carefully.

Use permethrin only on the skin. Do not let it get in your mouth or eyes. Flush the eyes if any medicine gets in them.

Do not put permethrin on a cut, scrape, or open sore. Flush the area if any of the medicine gets on a cut, scrape, or open sore.

How to use permethrin cream:

• Permethrin cream is used to treat scabies.

• Massage the cream into cool, dry skin from the head to the soles. 

• Leave the medicine on the skin for 8–14 hours.

• Take a bath or shower to wash it off.

• Retreatment is rarely necessary unless mites are evident 14 days after treatment.

What to do before using permethrin lotion or rinse:

• Over-the-counter permethrin lotions and rinses treat head lice.

• For treatment to be successful, there are a few things you must do first to prevent reinfection. 

• Check all family members for head lice using a comb or two pencils to part the hair and locate lice and nits (eggs) near the scalp. Start with the scalp near the back of the neck and behind the ears.

• All family members with lice or nits must be treated.

• Remove the nits first with a nit comb.

• Wash all headgear, coats, scarves, towels, and bed linens in hot water and dry at the hottest setting for at least 20 minutes. 

• Soak all combs and hairbrushes for 10 minutes in hot water (130˚ or hotter).

• Anything that comes in contact with the hair or scalp that cannot be washed should be dry-cleaned, sealed in a plastic bag for four weeks, or disinfected with permethrin spray.

How to use permethrin lotion or rinse:

• Permethrin lotions and rinses should be applied to the scalp only. Do not apply to other parts of the body.

• Do not use permethrin lotion or rinse unless you or a healthcare provider have found head lice or nits in your hair.

• Wash the hair with shampoo alone, no conditioner.

• Towel dry the hair so that it’s still damp. Do not use this towel again until it has been washed in hot water.

• Shake the permethrin bottle well.

• Be very careful not to get permethrin in your eyes. Put a washcloth or towel over your eyes to protect them before applying this medicine.

• Saturate the hair with permethrin. Start at the neck and behind the ears.

• Leave the medicine on the hair for 10 minutes.

• Rinse it out with warm water.

• Towel dry the hair with a towel that has been washed in hot water.

• A second treatment is only necessary if lice or nits reappear in seven days.

Store permethrin cream, lotion, or rinse at room temperature.

Permethrin is only used once. 

Whether using prescription or nonprescription permethrin, apply a missed dose at any time.

Do not apply a second dose of permethrin cream without a prescription from a doctor.

Do not apply a second dose of permethrin lotion for at least seven days. Do not apply that second dose unless you can see lice or nits in the hair or scalp.

This medicine is not right for everyone. 

Do not use it if you have had an allergic reaction to permethrin or to similar insecticides that contain phenothrin (sumithrin) or pyrethrin.

Before using permethrin, talk to a doctor if you are pregnant, breastfeeding, or have asthma or allergies, particularly ragweed allergy.

When using permethrin, immediately wash it off and stop use if you experience an allergic reaction. Contact a doctor.

Do not use this medicine on an infant younger than 2 months of age.

Do not use this medicine on your eyebrows or eyelashes. Talk to a doctor or pediatrician.

If permethrin is swallowed, get emergency medical attention.

Permethrin lice-killing spray IS NOT FOR USE ON PEOPLE but can be used to disinfect household items that cannot be washed like mattresses and couches. 

It’s important to keep all medicine and insecticides out of the reach of children. Be extra careful to make sure no child has access to permethrin products.

Topical permethrin has no known drug interactions.

Keep all medicine out of the reach of children. Never share your medicine with anyone.