Many head lice treatments come as lotions that a person applies to their hair and scalp. Some people may refer to these treatments as “lice shampoo.”

Head lice are insects that primarily live on the human scalp and consume blood several times daily. While lice do not spread disease, they can cause itching and irritation.

This article explains how lice shampoo works, how to use it, and how to prevent lice. It lso answers some common questions about lice shampoo.

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Over-the-counter (OTC) head lice treatments contain pyrethrins or permethrin.

Pyrethrins are natural compounds from the chrysanthemum flower, and permethrin is a synthetic version of these compounds. These treatments are pediculicides, which means that they kill lice.

However, OTC lice treatments do not kill nits, which are unhatched lice eggs.

For this reason, the Centers for Disease Control and Prevention (CDC) recommends retreating hair about 9–10 days after using a pyrethrin or permethrin lice shampoo for the first time. This is to kill any new lice that have hatched from nits since the first treatment.

Prescription treatments

A doctor can prescribe a stronger medication if OTC head lice treatments do not work.

Prescription treatments may include lotions or topical suspensions that contain the following ingredients:

  • malathion
  • benzyl alcohol
  • ivermectin
  • spinosad

Some of these treatments kill nits as well as adult lice.

Lindane shampoo

Lindane is only available as a shampoo. It is a potent medication that may be toxic if a person swallows it. Lindane is not available in California due to its potential toxicity.

According to a 2018 review, Lindane is no longer an acceptable head lice therapy due to the risks of use. However, the CDC still lists Lindane as a second-line option for treatment.

The CDC advises that Lindane is not suitable for:

  • infants and children
  • older adults
  • anyone who has extremely irritated skin or sores where they will apply the shampoo
  • pregnant people or individuals who are breastfeeding
  • people with HIV
  • people with a seizure disorder
  • anyone who weighs under 110 pounds

It is important for people to only use lice shampoo in cases where they have noticed live lice crawling in the hair or are otherwise certain that the person receiving the treatment has head lice.

Treatment with lice shampoo typically involves four stages.

The first treatment

People will need to read the instructions carefully before using a lice shampoo.

Many lice shampoos are available, each with slightly different methods. It is important that people familiarise themselves with their chosen product’s treatment process. Often, this will involve lathering the shampoo into the hair, leaving it on for several minutes, then rinsing.

People will also need to do the following when using lice shampoo:

  • Limit the amount of skin the product touches: Some lice treatments may irritate the skin. A person having lice shampoo treatment should be fully dressed to minimize contact with the skin. People should not use lice shampoo in the shower or bath.
  • Use a single product: Combining products may lead to harmful interactions between medications. People can speak with a doctor or pharmacist about treatments that are safe to use together.
  • Only use the amount stated on the bottle: Using more than the recommended amount does not increase the likelihood of killing more lice and may be unsafe.
  • Use a lice comb: Many lice treatments come with a lice comb, which has closer teeth than a regular comb. This makes them more effective at removing lice and nits from the hair.

Checking the hair

It is best to check the hair and scalp around 8–12 hours after using lice shampoo.

The lice should be less active. If they are still moving around as much as before the treatment, people can speak with a healthcare professional about trying a different treatment.

What to do the next day

People will need to avoid washing their hair for 48 hours after lice treatment. This allows the medication to continue working.

Guidelines also suggest a person comb through the hair with a lice comb once a day for 2–3 weeks to make sure that the lice leave the scalp.


Instructions for OTC shampoos may recommend completing another treatment 7–9 days after the first. This is because lice shampoos mainly kill adult lice, so the extra week allows any nits to hatch.

After the second treatment, a person will complete the same steps as after the first treatment, including:

  • combing the hair through with a lice comb
  • avoiding washing the hair for 2 days
  • continuing to comb the hair with a lice comb daily for 2–3 weeks

Methods to prevent lice include avoiding the following:

  • head-to-head contact
  • sharing stuffed animals, towels, or clothes, especially hats and scarves
  • sharing hair accessories, brushes, and combs
  • lying down on beds, pillows, carpets, and couches that a person with lice has recently used

It is also best to machine wash and dry clothes and bed linens that a person with lice has used in the 2 days leading up to treatment. The cycle should run at 130° Fahrenheit.

People can store nonwashable items in a sealed plastic bag for 2 weeks to allow the lice to die. Alternatively, they can take them for dry cleaning.

Below are some common questions and answers about lice shampoo.

How long does it take for lice shampoo to kill lice?

Lice shampoo should start killing hatched lice within 8-12 hours. However, many lice shampoos do not kill lice eggs, also called nits.

Are the nits dead after using lice shampoo?

Some prescription-strength lice treatments may also kill some nits.

However, many lice treatments do not kill nits. Most lice shampoo manufacturers recommend retreatment about 9 days after the initial treatment to kill the remaining nits after they have hatched into lice.

A person can speak with a doctor if they are unsure about how to use lice shampoo.

Can lice go away on their own?

Lice do not go away without treatment. Even if they die naturally, they may have laid nits that will hatch and continue feeding on the scalp.

OTC lice shampoos kill lice but not their eggs, which people call nits. Some prescription-strength lice treatments may also kill some nits. People typically need to apply lice treatments on two separate occasions to kill all the lice.

Lice shampoos usually come with a lice comb and always come with instructions for safe use. It is best to speak with a healthcare professional about other options if treatment is ineffective. People can also consult a healthcare professional if they are unsure how to use lice treatments.