Head lice facts every parent should know

Head lice are small parasites that live on human scalps, feeding on blood. While they don’t cause serious health problems, head lice are a common and frustrating problem, especially among school-aged children. Dr. Amy Silverio, a pediatrician at Lurie Children’s Primary Care: Chicago Area Pediatrics, provides practical tips for spotting and treating head lice in kids.

“Though lice don't transmit diseases, infestations can lead to itching, discomfort and stress for both kids and adults,” explains Silverio explains.

Head lice have three main life stages: egg, nymph and adult. Lice eggs, or “nits,” are oval and yellowish white, about the size of a knot in thread. Nymphs are young lice that look like adults but are tiny, about the size of a pinhead. Adult lice, which are tan to grayish white, are around the size of a sesame seed. They have six legs with claws to cling tightly to hair strands. Each day, an adult female louse lays up to eight eggs on hair strands near the scalp.

“Eggs need to be close to the scalp to be at an ideal temperature for survival,” Silverio says. These eggs hatch into nymphs in about seven to 12 days, and the nymphs mature into adults in about nine days.”

A common myth is that lice jump or fly, which makes people think they spread easily.

“Lice cannot jump, hop or fly; they crawl,” Silverio says. “They spread mainly through head-to-head contact, which is typical during playtime among kids.” Lice infestations are most common among children between the ages of 3 and 11. Importantly, getting lice is not a sign of poor hygiene.

“Lice can attach to the hair of anyone, whether it’s clean or dirty. Adults can get lice too, especially if they are in close contact with an infested person,” Silverio notes​.

To check for lice, it’s best to start with wet hair and a bright light. Wear gloves, part the hair in sections, and look closely at the scalp. “Look for lice crawling on the scalp or on the hair strands, particularly near the back of the neck and behind the ears, where lice are often found,” advises Silverio. She also suggests looking for eggs about a quarter of an inch from the scalp, as they are usually attached firmly to hair strands near the roots​.

The most common sign of lice is itching, which can appear four to six weeks after the infestation begins. “It can feel like a tickling sensation on the head,” says Dr. Silverio. In addition to itching, children may feel as if something is moving on their scalp. Because lice spread easily among children, it’s best to treat an active infestation promptly to avoid passing it on to others​.

There are various treatment options for head lice, ranging from over-the-counter to prescription medications. Some lice have become resistant to certain over-the-counter treatments, so a prescription may be needed.

“Treatment should only be initiated if there is a diagnosis of active head lice infestation,” Silverio says. “The presence of nits alone does not justify treatment, as nits may just be empty eggshells.” Some treatments may require reapplication to ensure all lice are killed. It's essential to follow the instructions carefully for whichever treatment you choose​.

To prevent lice infestations, it's helpful to check for lice regularly, especially if someone in the household has already been infested. Avoid head-to-head contact during play and don’t share items like hats, brushes, combs or towels. Silverio also recommends disinfecting combs and brushes by soaking them in hot water (at least 130°F) for five to 10 minutes. Additionally, any clothing, bedding, or items used by an infested person within the two days before treatment should be washed in hot water and dried on a high-heat cycle. If something can’t be washed, it can be sealed in a plastic bag for two weeks to kill any lice that may still be present​.

Head lice are a common issue for children, but with proper care and preventive measures, they are manageable.

“Lice are a nuisance, but they’re treatable and preventable with the right approach. Understanding how they spread and the best ways to handle them can minimize the impact on your family,” Silverio says.

• Children's health is a continuing series. This column was provided by Ann & Robert H. Lurie Children's Hospital of Chicago.