What to Do When Your Child Has Head Lice

For a minuscule, relatively harmless pest, the head louse is greatly feared among parents of young children. It’s understandable: Something about creepy crawly bugs that hide in your hair is unsettling. By the time you finish this article, you’ll probably feel phantom tingles on your scalp and a sudden urge to scratch.

Six to 12 million children age 3 to 11 get lice every year, according to estimates from the Centers for Disease Control and Prevention. My own family has battled lice twice. Both times, I got infected after a kid climbed into my bed at night and shared my pillow. I have spent hours dragging lice combs through my children’s hair, visited a neighborhood hair salon where the stylist was known — through hush-hush word of mouth — to comb out lice after-hours, and even once paid for a house call. All told, I have spent more than $1,000 delousing my family.

According to experts, however, I didn’t need to. While head lice are contagious, they are not hardy or resilient. You don’t need to light a bonfire of bedsheets and stuffed animals to rid your house of them.

Here’s how to identify and deal with an infestation.

How do you know it’s head lice?

Lice can be easy to miss. Adults, which are grayish white and the size of a sesame seed, are most active at night and hide from light. “A person with an active infestation may only have 10 adult lice on their head, and they are fast,” said Dr. Laura Melnick, an assistant professor of clinical dermatology and pediatrics at Weill Cornell Medicine in New York. Nymphs, the baby lice, look similar but are smaller. Eggs, or nits, are what you usually find during an at-home check. “Think if you tied a knot in a thread — nits are the size of that knot” and laid within a centimeter of the scalp, said Dr. Candace Johnson, an assistant professor of pediatrics and hospital epidemiologist at Columbia University.

The best places to check for eggs are behind the ears or at the nape of the neck, where individual hairs are easier to isolate.

You can tell lice from dandruff or seborrheic dermatitis — an itchy skin condition — because dandruff flakes brush off (eggs don’t) and dermatitis causes crustiness on the scalp.

I found nits. What now?

Remember: Lice are icky but harmless. “They do not carry disease,” Dr. Johnson said. “And it’s a myth that they are linked to poor hygiene. They’re just a nuisance.” Start by checking everyone in the family. (Pets can’t get lice from humans.) The pests pass through head-to-head contact — that’s why young kids who pile onto classroom rugs like puppies are most susceptible. They can spread through shared hats or hair brushes, but it is less likely. “Lice do not fly or jump — they crawl,” Dr. Johnson said.

Then it’s time for treatment. Over-the-counter products like Nix and Rid that contain permethrin or pyrethrins can kill adult lice. Follow the instructions: Lice have a two-week life cycle, so you’ll need to apply products twice, a week or so apart.

These ingredients have been approved by the Food and Drug Administration — permethrin for children 2 months and older, and pyrethrins for age two and older. Another product, called Sklice and also sold under the generic name ivermectin, is approved for children 6 months and up.

For parents who worry about putting harsh chemicals on young heads, doctors have reassurances. You’re only using the products for a short time, and “they have been studied and are safe,” said Dr. Justine Fenner Biederman, an assistant professor of dermatology and pediatrics at Mount Sinai Icahn School of Medicine.

Occlusive agents — thick, water-repellent substances like mayonnaise or lotion — can kill lice, although doctors emphasize that these D.I.Y. treatments are not well studied. If you go this route, Dr. Melnick recommends 100 percent petrolatum (Vaseline), which won’t cause allergic reactions.

What about combing?

Creams and shampoos can’t kill eggs, so your child will still have nits in between treatments. Combing is the only way to remove them. “It’s not necessary to prevent the spread, as nits do not move,” Dr. Melnick said. But waiting while knowing eggs remain can be nerve-racking. And some schools won’t let kids return if they still have nits, even though the C.D.C. and the American Academy of Pediatrics both advise against no-nit policies.

You need a fine-tooth metal comb designed for lice removal. Start with wet hair and go through small sections. Repeat the process every two to three days for two weeks, and remember to still use medicated cream as directed. Any nits missed during combing can hatch, sending you back to square one if they go untreated.

For parents who want to leave it to the professionals, some cities have lice-removal boutiques, where trained technicians will comb through your child’s hair. This service typically costs hundreds of dollars.

How do I thoroughly clean my house?

Wash sheets, towels, hats, clothes and jackets in hot water and dry them on high heat. Adult lice cannot live away from a human head for more than a day or two, so you don’t need to wash T-shirts that haven’t seen the light of day in a month. If your child’s stuffed animals can’t go through the washing machine, put them in a plastic bag for two weeks. Make sure to vacuum couches, rugs and car seat headrests.

Is there a magic way to avoid lice?

Preventive shampoos exist, but there’s no research showing they work, and the essential oils in them may cause irritation, Dr. Fenner Biederman said. Braiding or tying up long hair that lice could crawl into might help and certainly won’t hurt.

If there is a lice outbreak in your child’s classroom, start checking — but again, don’t freak out.

“Most children who are exposed to head lice are not going to get it,” Dr. Melnick said. “It might not feel that way, but it’s the truth.”