Health Debunked: Are Head Lice More Attracted to Clean Hair?

If you’re like most people, just the thought of head lice might have you reaching up to reflexively scratch your scalp and shudder. But head lice have been around for as long as humans have been alive.

In fact, we have coexisted since ancient times — which is why even mummies from ancient Egypt have been found to have lice! So, chances are at some point you or someone you know is going to have a run-in with these little critters.

While some people have wondered if hygiene contributes to catching lice, others have heard the rumor that lice actually prefer clean hair. So, which is it? Read below to find out what the science says.

What are head lice?

Head lice, or Pediculus humanis capitus, are tiny insects that attach to the base of the hair shaft on your head and neck. They feed on blood several times a day, which is why they stay close to the scalp. Without an active source of blood, an adult louse will die within 1 to 2 days.

There are three stages to the life cycle:

• Eggs: These are known as nits. They are attached to the hair shaft near the base at the scalp and can often be confused with dandruff or hair spray droplets. They are yellow to white and located within half a centimeter of the scalp.

• Nymphs: Nymphs hatch from the egg and look like an adult louse, but they are very hard to see. Typically, they’re about the size of a pinhead.

• Adults: The adult louse is the size of a sesame seed and has six legs, each with a small claw. They are tan to grayish white, but they often appear darker in people with dark hair. Adult lice can live up to 30 days on a person’s head and female lice can lay up to 10 eggs per day.

Why do people think they like clean hair?

Some people think that lice prefer clean hair because they are attracted to the smell of shampooed hair. Others believe that a clean hair shaft allows them to attach more firmly to the base of the skull because the oil from greasy hair acts as a repellent.

Claim: Head lice are more attracted to clean hair

The idea is that head lice are attracted to clean hair more than dirty hair. And so, they’re more likely to be found in the scalp of those who keep their hair squeaky clean. But is there any evidence to support this idea? Here’s what the science and leading experts have to say.

What does the science say?

Most cases of lice happen in preschool- and elementary school-aged children and their household contacts. It’s estimated that about 6 to 12 million lice infestations occur each year in the U.S. among children 3 to 11 years of age.

Lice cannot jump or fly, so they need close contact for transmission. They need to crawl from one head of hair to another. It turns out that they don’t have a preference for clean versus dirty hair. They just need to be close to move from one head of hair to another.

One study from Norway looked at other factors of hair to see if they might change transmission rates — it turns out there is no difference in transmission based on thickness, color, or type (curly or straight). What did seem to affect rates was the length of hair. Children with short hair were less likely to have lice than children with longer hair.

Anything that makes it more likely for a person’s hair to come into contact with another person’s hair can raise the chances of catching lice. Other factors that are associated with head-to-head contact and a greater chance of transmission may include:

• Young age

• Female gender

• A history of previous lice infection

• Many people living in household

• Sharing of combs

What do the experts say?

The American Academy of Pediatrics (AAP) recently published updated guidelines about diagnosing and managing lice. Dawn Nolt, MD, MPH, FAAP and lead author of the report states, “Head lice are an unpleasant part of the human experience, but they can be successfully managed and are no reason for a child to miss school.”

The AAP states that head lice screening programs in schools don’t actually work to lower the number of head lice cases. The best way to avoid getting head lice is to avoid sharing personal items, like combs or hats. Regular checks by a parent can also help with early detection and treatment.

How are lice diagnosed?

Lice are most often diagnosed by visually inspecting the scalp and seeing either the eggs, adult lice, or both. But, it can be difficult to see the live lice. This is because they tend to avoid light and can crawl quickly. So, it may be easier to diagnose lice with a specific louse comb.

Some experts recommend wetting the hair first and/or using conditioner to “slow down” the movement of the lice. This also gets rid of any static electricity, which can move the louse around. In fact, one study showed that combing dry hair that has lice could create enough static electricity to move the louse up to 1 meter!

If you are unsure if you are seeing lice eggs or something like dandruff or hairspray particles, you can reach out to your healthcare provider for more guidance.

How are lice treated?

There are various topical treatments for lice. The most commonly used is permethrin 1%. This is the main ingredient in most over-the-counter (OTC) treatments for lice. But, it’s important to wash the hair with nonconditioning shampoo first since conditioner can attach to the hair shaft and interfere with the medication.

If any live lice are seen, you should repeat the dose around 9 days after the original use. Resistance to permethrin has been reported, but it is not clear how common this is.

Other treatment options include:

• Pyrethrins plus piperonyl butoxide: These compounds are neurotoxic to lice but have low toxicity to mammals. They are becoming less effective due to higher rates of resistance.

• Prescription-strength medications: There are several newer prescription-strength topical treatments that your healthcare provider can prescribe. These are usually used in cases where OTC treatment didn’t work. The most commonly used is benzyl alcohol 5%.

Manual removal of lice can also be very effective for treatment of lice. And it is most effective when it is used after a topical treatment.

Wet the hair and start at the scalp, combing through small chunks of hair at a time to remove all nits and lice. The process is tedious but generally effective. Electronic nit combs are also available. But there’s no good research on whether or not they are more effective than regular fine-toothed combs.

Keep in mind that lice can survive outside of the scalp for 1 to 2 days, so you should clean any items that could have come into contact with hair on high-heat settings. For example, hats, scarves, and pillowcases should be washed on high-heat water and air settings. Items that can’t be washed on high-heat settings (like hairbrushes and combs) can be sealed in an air-tight container or bag for several days.

All household contacts should be checked for the presence of lice. Some experts feel that all household contacts should do one treatment for lice just to be on the safe side.

So, do lice like clean hair?

Yes and no. Turns out that lice like clean hair and dirty equally.

While they are more likely to be found on long hair, lice do not have any preference for hair based on cleanliness, color, thickness, or type (curly or straight). The truth is that exposure to lice is a fact of life and largely unavoidable. This is especially true for young children and their household contacts.

And the best way to limit the spread is to check children in the home regularly and start treatment quickly when diagnosed.

Why trust our experts?

Written by:

Karen Hovav, MD, FAAP

Karen Hovav, MD, FAAP, has more than 15 years of experience as an attending pediatrician in a variety of clinical settings. She has worked in a large academic center in an urban city, a small community hospital, a private practice, and an urgent care clinic.

Edited by:

Kelsey Abkin

Kelsey Abkin has been working as a journalist since 2016. She has held many titles throughout her career, including editor, content strategist, digital strategist, and writer.

Reviewed by:

Patricia Pinto-Garcia, MD, MPH

Patricia Pinto-Garcia, MD, MPH, is a medical editor at GoodRx. She is a licensed, board-certified pediatrician with more than a decade of experience in academic medicine.

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