Lice refer to parasitic insects that can live on the human body. Different types of human lice may be present on people’s heads and bodies and survive by feeding on human blood. Typically, human lice spread from close person-to-person contact.

Health experts can classify human lice into three types:

Each type of human louse is a parasitic insect that cannot hop or fly. As such, human lice commonly spread through close person-to-person contact. It is also possible for people to get lice through contact with clothing, bedding, and grooming tools. Dogs, cats, and other pets do not play a role in spreading lice.

To help prevent the spread of lice, it is advisable to regularly wash and dry clothing and bedding at a high temperature, avoid close physical contact if a person has lice, and avoid sharing personal items.

This article discusses how head lice spread and strategies to prevent them.

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Each type of human louse spreads slightly differently. However, lice spreading involves close physical contact between humans.

Head lice commonly spread from direct head-to-head or hair-to-hair contact. However, it is also possible for them to spread by sharing clothing or belongings that experience contact with lice.

Similarly, body lice usually spread from direct contact with an individual with an infestation or from their clothing or bedding if they have an infestation.

Also known as crabs, pubic lice are a type of sexually transmitted infection (STI). This means that they spread directly from person to person through sexual contact. In rare cases, pubic lice may also spread by clothing, bedding, or a toilet seat.

Evidence notes that in the United States, head lice are most common among:

  • preschool children attending child care
  • elementary school children
  • households with children

In the U.S., infestation with body lice occurs most frequently in individuals who do not have regular access to bathing and changes of clean clothes. For example, those individuals may include people experiencing homelessness or people residing in shelters.

Since pubic lice mainly spread through sexual contact, they are most common in sexually active adults. However, it is important to note that pubic lice present on children may be a sign of sexual exposure or abuse.

The primary symptom of head, body, and pubic lice is itching that occurs due to the presence of the lice. The itching typically occurs due to a person experiencing an allergic reaction to bites from lice. This intense itching can result in sores from scratching that may be at risk of infection with bacteria or fungi.

With head lice, a person may also notice a tickling sensation on their scalp and experience irritability and difficulty sleeping. Heavily bitten areas of skin from body lice may thicken and present with discoloration. A person may also see visible pubic lice eggs or crawling pubic lice around their pubic region.

To treat human lice, it is generally advisable to use a pediculicide. This refers to medication that kills lice. It is available in different formulations, and some also have an ovicidal effect, which means they also kill lice eggs.

For head lice, in addition to using a pediculicide, a person can also use a nit comb to help remove nits and lice from the hair shaft.

Similarly, for pubic lice, a person can apply medication to their pubic area and can use a fine-toothed comb or their fingernails to remove nits. If lice are still present after 7–10 days, it is advisable to reapply the pediculicide.

With body lice, it may not be necessary to use a pediculicide. Instead, a person can treat body lice by:

  • improving personal hygiene
  • assuring a regular change of clean clothes
  • washing and drying clothes, bedding, and towels at a high temperature

Tips for preventing head lice include avoiding:

  • experiencing head-to-head contact
  • sharing clothing, such as hats, scarves, and hair ribbons, and sharing combs, brushes, or towels
  • lying on beds, pillows, or couches that experience contact with a person with head lice
  • using fumigation sprays or fogs, as they can be toxic if a person inhales them or absorbs them through skin

Other prevention tips for head lice include:

  • disinfecting items such as combs by soaking them in hot water
  • washing and drying clothing and other items a person with head lice has used for head-to-head contact
  • dry-cleaning or storing nonwashable items in a plastic bag for 2 weeks
  • vacuuming the floor and furniture

For body lice, the following preventive strategies can help:

  • bathing and changing into properly laundered clothes at least once a week
  • machine-washing and drying clothing and bedding using a hot water laundry cycle and high heat drying cycle
  • dry-cleaning or sealing away nonwashable items in a plastic bag and storing them for 2 weeks
  • avoiding sharing clothing, beds, bedding, and towels with a person with body lice
  • fumigating and using chemical insecticides to manage and prevent lice and diseases, such as epidemic typhus

People can use the following methods to help prevent and manage the spread of pubic lice:

  • receiving treatment if they have pubic lice
  • notifying all sexual contacts if they have pubic lice
  • abstaining from sexual contact until they are clear of lice
  • machine-washing and drying both clothing and bedding in hot water at a temperature of at least 130°F (54°C)
  • dry-cleaning or sealing items that are not washable in a plastic bag and storing them for 2 weeks
  • avoiding sharing clothing, bedding, or towels with an individual with pubic lice
  • refraining from using fumigant sprays or fogs, as they can be toxic to humans
  • testing for other STIs that may be present

Human lice are parasitic insects that feed on human blood. Different types may be present on several human body parts. Generally, lice spread from close physical contact between humans and cause symptoms such as itching.

Medications are available to treat lice infestations. Additionally, people can try to prevent them by limiting physical contact if a person has lice, avoiding sharing personal items, and regularly washing and drying clothing, bedding, and towels at a high temperature.