Overview

Lice are tiny, wingless, parasitic insects that feed on human blood. Lice are easily spread — especially by schoolchildren — through close personal contact and by sharing belongings.

There are three types of lice:

  • Head lice. These lice are found on your scalp. They're easiest to see at the nape of the neck and over the ears.
  • Body lice. These lice live in clothing and on bedding and move onto your skin to feed. Body lice most often affect people who aren't able to bathe or launder clothing regularly, such as homeless individuals.
  • Pubic lice. Commonly called crabs, these lice occur on the skin and hair of the pubic area and, less frequently, on coarse body hair, such as chest hair, eyebrows or eyelashes.

People can have good personal hygiene and still get lice. Unless treated properly, this condition can become a recurring problem.

Symptoms

Common signs and symptoms of lice include:

  • Intense itching on the scalp, body or in the genital area.
  • Tickling feeling from movement of hair.
  • Lice on your scalp, body, clothing, or pubic or other body hair. Adult lice may be about the size of a sesame seed or slightly larger.
  • Lice eggs (nits) on hair shafts. Nits may be difficult to see because they're very tiny. They're easiest to spot around the ears and the nape of the neck. Nits can be mistaken for dandruff, but unlike dandruff, they can't be easily brushed out of hair.
  • Sores on the scalp, neck and shoulders. Scratching can lead to small red bumps that can sometimes get infected with bacteria.
  • Bite marks especially around the waist, groin, upper thighs and pubic area.

When to see a doctor

See your doctor if you suspect a lice infestation. Things often mistaken for nits include:

  • Dandruff
  • Residue from hair products
  • Bead of dead hair tissue on a hair shaft (hair cast)
  • Scabs, dirt or other debris
  • Other small insects found in the hair

Causes

Lice feed on human blood and can infest the human head, body and pubic area. The female louse produces a sticky substance that firmly attaches each egg to the base of a hair shaft. Eggs hatch in six to nine days.

You can get lice by coming into contact with either lice or their eggs. Lice can't jump or fly. They spread through:

  • Head-to-head or body-to-body contact. This may occur as children or family members play or interact closely.
  • Proximity of stored belongings. Storing infested clothing in closets, lockers or on side-by-side hooks at school, or storing personal items such as pillows, blankets, combs and stuffed toys in proximity at home can permit lice to spread.
  • Items shared among friends or family members. These may include clothing, headphones, brushes, combs, hair decorations, towels, blankets, pillows and stuffed toys.
  • Contact with contaminated furniture. Lying on a bed or sitting in overstuffed, cloth-covered furniture recently used by someone with lice can spread them. Lice can live for one to two days off the body.
  • Sexual contact. Pubic lice usually spread through sexual contact and most commonly affect adults. Pubic lice found on children may be a sign of sexual exposure or abuse.

Prevention

It's difficult to prevent the spread of head lice among children in child care and school settings. There's so much close contact among children and their belongings that lice can spread easily. It's no reflection on your hygiene habits or those of your children, and it's not a failure on your part as a parent if your child gets head lice.

Some over-the-counter products claim to repel lice, but more scientific research is needed to prove their safety and effectiveness.

A number of small studies have shown that ingredients in some of these products — mostly plant oils such as coconut, olive, rosemary and tea tree — may work to repel lice. However, these products are classified as "natural" so they aren't regulated by the Food and Drug Administration (FDA), and their safety and effectiveness haven't been tested to FDA standards.

Until more research proves the effectiveness of head lice prevention products, the best approach is simply to take thorough steps to get rid of the lice — and their eggs — so that you don't have more lice to deal with.

  • Ask your child to avoid head-to-head contact with classmates during play and other activities.
  • Instruct your child not to share personal belongings such as hats, scarves, coats, combs, brushes, hair accessories and headphones.
  • Tell your child to avoid shared spaces where hats and clothing from more than one student are hung on a common hook or kept in a locker.

However, it's not realistic to expect that you and your child can eliminate all the types of contact that may result in the spread of lice.

Your child may have nits in his or her hair but not necessarily develop a case of head lice. Some nits are empty eggs. However, nits that are found within 1/4 inch (6.4 millimeters) of the scalp should be treated — even if you find only one — to prevent the possibility of hatching.

Nits that are farther away from the scalp are probably from an old infestation, but should be removed to prevent a recurrence.

May 23, 2020
  1. Devore CD, et al. Head lice. Pediatrics. 2015; doi:10.1542/peds.2015-0746.
  2. AskMayoExpert. Lice. Mayo Clinic; 2020.
  3. Bennett JE, et al. Lice (Pediculosis). In: Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 9th ed. Elsevier; 2020. https://www.clinicalkey.com. Accessed March 21, 2020.
  4. Goldstein AO, et al. Pediculosis capitis. https://www.uptodate.com/contents/search. Accessed March 21, 2020.
  5. Head lice: Treatment frequently asked questions. Centers for Disease Control and Prevention. https://www.cdc.gov/parasites/lice/head/gen_info/faqs_treat.html. Accessed March 21, 2020.
  6. Lice. Centers for Disease Control and Prevention. https://www.cdc.gov/parasites/lice/index.html. Accessed March, 21, 2020.
  7. Gunning K, et al. Lice and scabies: Treatment update. American Family Physician. 2019. https://www.aafp.org/afp/2019/0515/p635.html. Accessed March 21, 2020.
  8. Imboden A. Effective treatments for head lice. The Nurse Practitioner. 2019; doi:10.1097/01.NPR.0000574668.19239.db.