A young girl has her hair inspected with a comb for lice.

With school now in full swing, you want to be sure your youngsters don’t come home with head lice.

But while these tiny, scalp-loving pests can cause plenty of irritation, itchiness, and concern, experts say that a lice infestation isn’t a cause for panic.

Of all the critters that commonly feed off of humans, “head lice are the least significant,” says Richard Pollack, Ph.D., a public health entomologist and a senior environmental public health officer at Harvard University. “Yet they have bubbled up forcibly to the top of what everyone fears.”

That may be partly because misconceptions abound about lice—about how they behave, where they’re spread, and how they’re best treated. Here, we asked experts to weigh in on four widespread beliefs and the truth behind them.

Myth: Lice Prefer Dirty Hair

The truth: Contrary to popular opinion, having lice doesn’t signify poor hygiene. In fact, lice are just as apt to make a home in freshly shampooed hair as they are in locks that could use a washing.

“They don’t care at all,” says Dawn H. Gouge, Ph.D., a public health entomologist at the University of Arizona. “They love warm little noggins.”

Myth: Kids Pick Up Lice Mainly at School

The truth: Although lice can be transmitted at school, kids can also “catch” them in a number of other places, including sleepovers, playgrounds, sporting activities, and camp.

And according to Gouge, the idea that school is the primary place for lice infestation has led many schools to implement “no nit” policies. These require children to be sent home from school or kept out of school if nits (lice eggs) are discovered on their scalps. In a new Consumer Reports nationally representative survey of 2,016 U.S. adults, we asked Americans whether their child had ever been sent home or asked to stay home from school because he or she had lice. Fifty-two percent of those with children in their household who’d dealt with a lice infestation in the previous five years said yes.

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But such policies have several flaws, according to the Centers for Disease Control and Prevention. It’s easy to mistake dandruff or debris for nits in hair. Plus, nits don’t move and, in fact, are affixed to hair shafts with a cementlike substance that makes it unlikely they can be transferred from one person to another. And there’s no evidence that banning kids with nits from the classroom is useful. The National Association of School Nurses notes that classroom or schoolwide nit checks aren’t effective at preventing incidences of lice in schools.

Keeping kids with nits (or lice) out of school has “absolutely no benefit to anybody,” Gouge says. And the American Academy of Pediatrics (AAP) has proclaimed that “no-nit policies are unjust and should be abandoned.” The cost of missed school far outweighs any risks of head lice, according to the CDC and the NASN.

Myth: Lice Spread by Jumping or Flying

The truth: Lice, which are wingless, don’t jump or fly. They don’t hop from place to place, either.

They can crawl, however, and very quickly, because their legs are very well adapted for crawling. And once they crawl onto a child’s head, they tend to hang on tightly, thanks to the hooklike claws they have at the end of their legs.

So how do they get from head to head? By crawling from one head to another, via direct head-to-head contact between two people.

Though it’s theoretically possible to pick up a louse from a public place, such as a movie theater seat, it would be highly unlikely. That’s because lice live on human heads, and they need to feed every 4 to 6 hours. Adults can survive only for about a day if they fall off. (They don’t live on pets, either—only people.)

In fact, it’s pretty unlikely that lice will be transmitted from person to person without direct head-to-head contact, Gouge says.

Even the sharing of helmets, clothes, pillows, and hairbrushes probably rarely leads to lice transmission, according to the CDC. The risk is greater, however, when these types of items are used by more than one child in quick succession, Gouge says. And if someone in your household does have lice, it’s a good idea to launder their bedding and clothes and to clean hair-care items as a precaution, according to the AAP.

Myth: Pesticide Must Be Used to Kill Them

The truth: Several pesticide-based treatments are available, either over the counter or by prescription. But these may not always be the best choice.

Sometimes called “super lice,” many of the pests in the U.S. and other parts of the world have developed resistance to over-the-counter lice treatments that contain certain pesticides, notably permethrin and pyrethrins. In a 2016 study on this topic, scientists found that 98 percent of the lice they evaluated—collected from 138 sites in 48 states—had a gene mutation indicating possible pesticide resistance. The researchers say that while the mutation doesn’t guarantee that an OTC lice product with permethrin or pyrethrins will fail, it does reduce the chances treatment will succeed.

Prescription lice treatments may be more effective but can be expensive. For instance, according to drug pricing website GoodRx, Sklice, a prescription treatment that contains the pesticide ivermectin, can cost $350 or more for a tube, and it might not be covered by insurance. And some pesticide products carry risks, such as malathion (Ovide and generic)—it’s flammable, and it can cause stinging and burns. CR’s experts recommend against using products containing the active ingredients malathion and lindane.  

Note that some prescription pesticide treatments should be used on children only of certain ages, may need to be used more than once, and are applied for varying lengths of time, so it’s important to read directions carefully.

And there are effective alternatives to pesticide-based products. Consumer Reports’ scientists have long advocated the use of wet-combing: coating your child’s head with conditioner or oil and combing out lice and nits with a fine-tooth metal nit comb. The AAP also recommends this method for parents who prefer not to use one of the available lice pesticides, or whose children are too young for them.

Learn more on the best ways to treat head lice.