What are lice?

The louse (plural: lice) is a parasite that attaches itself to human hair and feeds on human blood. The most prevalent kind of lice is head lice. An infestation with head lice is medically known as Pediculosis capitis. The Centers for Disease Control and Prevention (CDC) estimate that up to 12 million lice infestations occur every year in the United States.

Female adult lice can lay up to six eggs every day. Eggs are laid right onto the shaft of hair. Those that are less than six millimeters from the scalp are most likely to hatch. The eggs are essentially glued on to the hair by secretions from the female louse.

The eggs take about a week to hatch, producing a nymph. The nymphs then go through three successive growth spurts. During these spurts, they molt until they reach adult size.

Adult lice are about the size of a sesame seed and can be very hard to see, because they can be any color from white to tan to brown.

Lice typically feed on blood four to five times each day. They use their mouth parts to bite into the skin and secrete a substance that acts to block clotting.

While it’s important to note that lice infestations can happen to anyone, some people are at a higher risk of coming into contact with lice.

Learn more: What do lice look like? »

Common types of lice include head lice, body lice, and pubic lice.

Head lice

Head lice are obligate parasites. This means that they cannot survive without a human host. This species can live only on human hosts, so you cannot get them from your dog, cat, guinea pig, or any other kind of furry pet you may have.

Lice don’t have wings, so they can’t fly. They have six legs with claws at the ends — that’s how they attach themselves to hair.

Head lice can settle anywhere on the scalp, but they’re commonly found on hairs at the back of the neck and around the ears, where it’s warmest.

Body lice

Body lice are slightly different from head lice because they lay their eggs on clothing instead of on the body. Body lice also live in clothing and only move onto the body to feed. Body lice can carry a number of diseases, such as:

  • louse-borne typhus
  • relapsing fever
  • trench fever

Body lice are the only kind of lice known to spread disease.

Pubic lice

Pubic lice are a species of lice with large front legs, making them resemble crabs underneath a microscope. They are the smallest type of lice. Pubic lice are nicknamed “crabs” and are usually transmitted from one person to another during sexual activity. They live in the hair of their host’s genital area and can cause itching.

Lice infestations can happen to anyone, but they are a particular concern for school-age children. It’s important to emphasize that poor hygiene — such as skipped baths or showers or any other hygiene issue — is not typically the cause of head lice.

Children who live in crowded conditions may have more of a problem with head lice. This is only because they’re living close to one another and may sleep in the same bed. There are only two ways head lice can spread from person to person. One is by direct head-to-head contact, as when children hug or put their heads together to look at the same book. The other way is by sharing hats, caps, hair ties, scarves, or any personal item such as combs or brushes.

Body lice are spread by lice living on unwashed clothing. Unlike other kinds of lice, the spread of body lice can be prevented fairly simply. Clothes should be washed often after wearing, and you should avoid sharing clothing with others.

Pubic lice (“crabs”) are spread through sexual activity. Children that contract pubic lice may be victims of sexual abuse.

There are a number of treatments that can effectively get rid of head lice. These include over-the-counter products, natural remedies, and prescription medications. However, it is important to note that there are no natural or alternative products recommended by the CDC for the treatment of lice.

Getting rid of lice completely involves three steps. No matter what kind of lice you have, the treatment process is essentially the same:

  1. Kill the lice.
  2. Kill and remove the eggs.
  3. Decontaminate any affected areas and clothing.

The most common treatment product for lice involves pediculicide shampoo. After applying this treatment to the affected area, hair should not be washed for up to two days.

You can use a special comb called a “nit comb” to carefully remove the eggs that have attached themselves to the hair shaft.

You should thoroughly vacuum any area of your home where hairs might have fallen. Any bedding or clothing that has been exposed to the lice needs to be machine washed in hot water.

You may wish to avoid the use of lice medications on yourself or your small children. Some natural products promise the same results as pediculicides. However, these “holistic” products are not regulated by the Food and Drug Administration. A natural product that is not regulated may carry its own risks, especially in small children. It’s also important to remember that these products may not be as effective as promised. Some studies have shown that essential oils may have a role in lice treatment. If you have lice, you may find relief with the following oils:

  • tea tree oil
  • eucalyptus oil
  • neem oil
  • lavender oil

“Super lice”

Lice seem to be building resistance to some commonly used products. The American Council of Science and Health reports that in certain areas of the United States, traditional lice treatment products are no longer as effective at getting rid of infestations. There are already products on the market, such as those containing ivermectin, that treat these so-called “super lice.” These stronger products require a doctor’s prescription.

There is no proven product or method that will completely eliminate the spread of lice, but there are steps you can take to lower your chances of getting it. Avoid head-to-head contact with other people whenever possible. Never share personal hygiene products, especially combs or brushes. Try to avoid “hot spots” such as shared locker spaces, coat hooks, and closets in public places. Tell your school-aged children about lice and the steps they can take to help minimize the risk of contracting it.

Occasionally, an allergy to lice feces will lead to a rash and additional discomfort in the affected person. Continuous scratching of an area (to relieve itching) can lead to breaking the skin barrier and, subsequently, an infection in that area. In rare cases, lice living on eyelashes can lead to eye inflammation and pinkeye. Sometimes the very idea of lice can lead to stress and sleepless nights for children and parents.

If lice eggs aren’t destroyed properly during the initial treatment, or if you have repeated contact with a person who has not treated their lice infestation completely, you may find yourself experiencing repeated infestations. If this occurs, you should repeat the entire treatment seven days from your initial treatment date.

Remember that getting lice is not a reflection on a person’s personal hygiene. While treating lice is generally never a pleasant experience, it’s fairly straightforward. Your life will most likely be lice-free again quickly.