Research does not suggest that the chlorine in some swimming pools kills head lice. However, many over-the-counter (OTC) and prescription treatments can kill them.

Head lice are small insects that live on a person’s scalp, where they consume blood. They may cause itchiness and discomfort. Additionally, they can crawl from person to person through direct contact and shared items, such as hats and hairbrushes. However, they do not transmit disease to humans.

This article explores chlorine and lice, whether people can use chlorine on their skin, and treatments that kill lice. It also discusses how individuals can help prevent lice and also answers some common questions about lice and chlorine.

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Chlorine is a chemical element present in some household and industry cleaners. The water in many swimming pools also contains chlorine, which people use to kill germs.

However, the Centers for Disease Control and Prevention (CDC) highlights that chlorine does not kill lice at the levels present in swimming pool water.

While head lice can survive in chlorinated pool water, they are unlikely to transmit to other swimming pool users while someone with lice is using the pool.

However, head lice may rarely transmit through several swimming-related activities and items. For example, this can occur when children share towels and hair brushes.

Chlorine can harm the skin in gas form and in higher concentrations, so a person should not use it to kill lice.

Learn about how to identify a chlorine rash.

Additionally, exposure to chlorine may lead to the following symptoms in humans, depending on the level and duration of exposure:

Read more about chlorine poisoning.

Only OTC and prescription treatments kill head lice. Some lice medications, or pediculicides, only kill lice, while others also kill lice eggs, which are known as nits.

OTC lice treatments include pyrethrins, in combination with piperonyl butoxide, and permethrins. Both of these treatments can kill live lice but not nits.

A doctor can prescribe higher-strength lice treatments, which may include:

  • malathion
  • ivermectin
  • spinosad
  • benzyl alcohol
  • lindane shampoo, which is a second-line treatment

People can speak with a healthcare professional about which treatment may be best for them and how to use it correctly. Some treatments require a person to comb the hair through with a nit comb.

Supplemental measures

Head lice typically die within around 24 hours if they do not feed on a human scalp. Additionally, people can take some measures to kill any lice that may have fallen off the hair and onto clothes, items, surfaces, and furniture.

These measures may include:

  • vacuuming the home, especially any floor and furniture upon which a person with lice has sat or laid
  • machine washing and drying clothing, bedspreads, and other items a person has worn within 2 days of treatment at 130°F (54.4°C)
  • soaking brushes and combs in water for 5–10 minutes at a temperature of 130°F (54.4°C) or more

A person can reduce the risk of lice transmission by avoiding hair-to-hair or head-to-head contact, which may occur among children while playing in particular.

They should also avoid sharing:

  • clothing or accessories, such as hats, hair ribbons, or scarves
  • hair care items, including brushes, combs, or towels
  • other items, such as pillows and stuffed animals

Below are answers to common questions about chlorine and lice.

Can chlorine interfere with lice treatment?

The CDC advises avoiding getting the hair wet through swimming or hair-washing for 1–2 days after undergoing treatment with certain lice medicines, as it may lessen its effectiveness.

How long can lice live on a hairbrush?

According to the CDC, adult lice can only live for about 24 hours when it leaves the human head, while young lice die after a few hours without feeding.

Chlorine in swimming pools does not kill head lice. Furthermore, chlorine can have irritating or even toxic effects in high levels and in its gas form.

Lice is still transmissible in a swimming environment, particularly if people share items such as swimming hats and towels.

The best way to treat lice is with OTC or prescription medication. A healthcare professional can advise which treatments may work best for someone and how to use them correctly.