Understanding Head Lice: What You Need to Know

What Are Head Lice and How to Identify Them

Lice, though not a serious health threat, are a significant nuisance, especially for school-aged children. These tiny parasites thrive on human blood, making human scalps their ideal environment. “While they don't transmit diseases, lice infestations can lead to discomfort, itching, and frustration for both children and adults,” says Amy Silverio, DO, a pediatrician at Lurie Children’s Primary Care: Chicago Area Pediatrics. 

Lice have three stages in their life cycle: egg, nymph and adult:

1. Eggs are oval and usually yellow/white in color and are the size of a knot in thread. Nits are empty egg castings that are white in color.
2. Nymphs are young lice and look like adult lice but are much smaller in size (the size of a pinhead).
3. Adult lice are tan to grayish-white in color and the size of a sesame seed with six legs that have claw. 

An adult female louse will lay and attach eggs (up to eight eggs per day) to the hair shaft close to the hair follicle. “Eggs need to be close to the scalp to be at an ideal temperature for survival,” said Dr. Silverio.  The eggs hatch into nymphs within seven-12 days of being laid. Nymphs become adults about nine-12 days after hatching. An adult louse can live on a human head for 30 days if left untreated. 

“A common myth is that lice jump and that makes them highly contagious. In fact, lice cannot jump, hop or fly but crawl,” said Dr. Silverio. “Infestation is most common among preschool and elementary school-aged children (most common between the ages of three-11). Kids get lice from head-to-head contact with a person who has head lice. Contact is common during play. It is not a sign of poor hygiene, and all socioeconomic groups are affected.” Adults are also susceptible to lice. Dr. Silverio said, “Lice can attach to the hair of anyone's head. It doesn't matter if the hair is clean or dirty and does not depend on hair length or texture. Adults can get head lice. Household members and caretakers of children with lice are at higher risk.” 

How to Check for Lice

It’s best to wet hair prior to inspection. Use a bright light, wear gloves and part hair to visualize the scalp. “Look for lice crawling on the scalp where the hair is parted or on the hair shaft. Look for eggs/nits near the hair follicle about ¼ inch from the scalp. Look behind both ears and near the back of the neck to look for lice, eggs or evidence of bites,” advised Dr. Silverio.  

Head Lice Symptoms and Treatment 

Itching is the most common symptom. It may take four-six weeks after an infestation for itching to appear. “Oftentimes, I hear that it can feel like a tickly sensation on the head,” shared Dr. Silverio.  

There are over-the-counter and prescription treatments available. Some lice have become resistant to over-the-counter treatments, and you may need to treat with a prescription. Costs and recommended age ranges vary by product. Retreatment may be needed.  

“Treatment should only be initiated if there is a diagnosis of active head lice infestation,” said Dr. Silverio. “The presence of nits alone does not justify treatment as nits may just be empty eggshells. 

Lice Prevention Tips 

• Regularly inspect household members or close contacts for lice if someone in the home is infested. 

• Avoid hair-to-hair contact during play and other activities.  

• Do not share clothing, combs, brushes or towels.  

• Do not lie on beds, couches, pillows, carpets or stuffed animals that have recently been in contact with an infested person.  

• Disinfect combs and brushes used by infested person by soaking in hot water (at least 130F) for 5-10 minutes.  

• Launder items that an infested person wore or used during the two days before treatment. Use hot water (at least 130F) and high heat drying cycle. If something can’t be washed, seal it in a plastic bag for two weeks.  

While lice are a nuisance, they are treatable and preventable with proper care and attention. By understanding what lice are, how they spread and how to properly treat and prevent infestations, you can minimize the discomfort and inconvenience caused by these tiny parasites. 

Learn more about Lurie Children's primary care services here.

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