why lice itch

Lice Symptoms, Causes, and Prevention

what causes lice

What causes lice? A friend or coworker gets lice, or your child’s school sends home a note, and suddenly you can’t stop thinking about lice. Do you have them? Does your child? How do you know? How do you prevent them?

 

Familiarizing yourself with symptoms, causes, prevention measures, and treatment options (and learning how to separate lice fact from lice myth) will help you make the best decisions.

 

What are lice?

A louse is a tiny parasite that feeds on human blood. (“Lice” is the plural form of “louse.”) They are wingless insects that spread through close contact and shared personal items. Head lice are the most common type of lice and infect children more often than adults.

 

Types of Lice

There are three types of lice:

 

  • Head lice infest the hair and scalp and are the most common type of lice. Anyone with hair can get head lice, but children are most commonly infested because of frequent, close contact.
  • Body lice live in clothing and bedding, often hiding in seams, and move onto the body to feed. Body lice are easily removed with regular washing, so they tend to infect poor and homeless populations most often.
  • Pubic lice, more commonly referred to as “crabs,” occur on the skin and hair in the pubic region. They can infest other coarse body hair—such as chest hair or eyebrows—but this is less common.

Signs you have lice

  • An Intense itching on the scalp, body, or in the genital area
  • A Tickling feeling from the 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

Why do lice itch?

Lice itch because their bites cause an allergic reaction. Insatiable itching is the most familiar symptom of a lice infestation. Head lice itching occurs on the scalp, around the ears, and along the neck—just below the hairline.

 

How long can you have lice before it itches?

Lice itching may not become noticeable for four to six weeks, especially if the infestation is light or if it is the first time the individual has had lice. If you think you notice a louse, or if the individual feels “tickling” on the scalp or skin, don’t ignore it just because the itching has not (yet) started.

 

How long do lice bites itch?

Each louse bite will itch for several days, so even after lice have been treated and removed, the itching may persist. Doctors often recommend an over-the-counter allergy medication to help ease the itching and reduce scratching.

 

5 Other Lice Symptoms

Itching is the most widely recognized symptom of lice, but it’s not always the first. Catching an infestation early often means being familiar with other lice symptoms as well:

 

  • A tickling sensation on the scalp or skin — Many individuals can feel lice on their skin before itching sets in. If children comment about a tickling or crawling sensation on the scalp, investigate immediately.
  • Sores on the scalp, neck, shoulders, or groin area — Intense scratching can lead to irritation and infection, which present as sores.
  • Bite marks — The allergens in lice bites often create raised, red marks on the skin. Head and pubic lice bites are most noticeable along the hairline. Body lice bites can be anywhere on the body.
  • Nits on hair shafts — Lice eggs are called “nits,” and head and pubic lice nits are glued to the base of hair shafts, near the scalp or skin. They are yellowish in color and extremely small. Head lice nits are often mistaken for dandruff, but they are much harder to remove than dandruff flakes.
  • Live lice — An adult louse is about the size of a sesame seed. Lice in hair are more easily seen by parting hair and investigating near the skin/scalp.

 

What causes lice?

Lice most commonly spread from one person to another by close contact. Head and pubic lice usually spread by hair-to-hair or bodily contact. They can also spread by sharing personal items, such as hats, combs, and pillows. These lice, however, cannot live long off of a host, so spreading via personal items is much less common.

 

Head lice are not easily washed away with normal shampoos and the insects are impartial to clean or dirty hair. Poor hygiene does not cause lice.

 

Body lice do not live on the human body, so they can be more easily spread by sharing clothes, bedding, or upholstered furniture. They are also spread by storing clothes or bedding near infested clothes or bedding.

 

Pubic lice are spread by sexual contact with an infected individual. 

 

Lice cannot jump or fly, so any kind of lice infestation is caused by physical contact between individuals or personal items.

 

Lice only feed on humans, so pets cannot bring them into the house.

 

By becoming informed on what causes lice you can better defend against it.

 

Lice Prevention

The only way to prevent lice is to avoid contact with infested individuals and items. As a lice infestation is often invisible for several weeks, however, it’s almost impossible to completely prevent lice. 

 

Reasonable precautions include:

 

  • Instructing children to avoid head-to-head or hair-to-hair contact as much as possible. 
  • Instructing children to avoid sharing hats, brushes, combs, and other hair accessories. 
  • Laundering all clothes and bedding regularly.

 

Lice Treatment Options

The best form of lice prevention is preventing the spread once you know someone in your family does have lice. 

 

  • Launder any infested clothes and bedding in hot water and dry on high heat for at least 20 minutes.
  • Put any soft items that cannot be washed—such as plush toys, hats, etc.—in the dryer for at least 30 minutes.
  • Soak hard items (that cannot go in the dryer) in hot water for at least 10 minutes.
  • Seal any other infected items in plastic for at least 48 hours.

 

Additional considerations for head or pubic lice:

 

  • Start an over-the-counter lice treatment immediately. Most solutions require a second application after seven to ten days (when existing nits hatch), so a complete treatment will take up to two weeks.
  • Avoid physical or hair-to-hair contact with other individuals until all treatments are completed, itching stops, and all signs of lice are gone.

 

Learn more about removing head lice for good → 

 

Additional considerations for body lice:

 

  • The infected individual should bathe and try to maintain regular hygiene.
  • Clothes should be changed and cleaned at least once each week.

 

When to See a Doctor for Lice

If you think you or a loved one has lice, but you aren’t sure, make an appointment with your doctor. Doctors have ready access to special lights and combs that can make it easier to identify an infestation.

 

Additionally, if over-the-counter lice treatment solutions are ineffective for head lice, you may be dealing with super lice. Most head lice cases in the U.S. are now a strain of super lice that are resistant to permethrin and/or pyrethrin—the two main ingredients in traditional OTC treatments. A doctor can write a prescription for stronger lice medication.

 

Stop Lice Itching

Lice make your head itch because of an allergic reaction to louse bites, but quick and effective treatment can prevent further spreading and ease symptoms as fast as possible.

 

Understanding a full range of lice symptoms, causes, prevention methods, and treatment options is the first step to dealing with lice appropriately. Take symptoms and warning signs seriously, do what you can to prevent lice from spreading, and start treatments quickly.

 

The next step is to keep an over-the-counter treatment option on-hand so that if an infestation does occur in your home, you can deal with it immediately—without running to the pharmacy or making a doctor’s appointment.

Jennifer Andreoli

Jennifer Andreoli is a New York Times bestselling author. She was born and raised in the Bronx and was a bookseller before shifting to children’s publishing and copywriting. She’s worked at a literary development company and a creative writing website for teens and as a book reviewer of children’s and young adult novels. She loves long walks on the beach and traveling to exotic locales and lives in Los Angeles. When she isn’t reading or writing great stories, she’s probably singing or watching racy shows on Netflix.

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