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Myths About Head Lice

Head lice and humans go way back; the parasites have been found with their little claws locked around prehistoric mummy hair. And our eons-long relationship has given us plenty of time to build up myths about lice, too. Here, Harvard lice expert Richard Pollack dispels some of the most persistent folklore:

Dirty Kids Spread Lice: Head lice have no preference for dirty hair or clean hair. "If you wash your hair three times a day or more, the lice on your head will just be clean lice," Pollack says.

Pets Spread Lice: Human head-lice infestations don't come from pets -- our lice only like our blood.

Brushes Spread Lice: Combs, brushes, headphones, hats and helmets have very little role in spreading lice. It's all the tumbling, playing and hugging that does it. In the vast majority of cases, lice are spread by direct head-to-head contact.

Clean House to Get Rid of Lice: If your house is dusty or dirty, go ahead and clean, says Pollack. But that won't prevent or cure a lice infestation. The parasites can't survive for more than a day without a meal of human blood, and they generally aren't going to let go of your hair to hang out on your couch. Changing bed linens or vacuuming a car seat can only help, but chances of a louse being on a bed or a car seat are incredibly small.

Shave Heads: "It's like using a cannon to kill a housefly," Pollack says. Completely shaving a head will get rid of lice eggs, but Pollack says that's a needless tactic when there are so many other effective and less drastic ways to solve the problem.

Head Lice Can Kill: Nope, that would be body lice. Those parasites do thrive in dirty environments and are perhaps most infamous for spreading deadly typhus in the 19th century. Head lice just make you itch.

Coat Your Head in Vaseline: Some people swear by the Vaseline or olive-oil treatments -- the idea is to suffocate the lice. But lice are extremely hard to suffocate, and to date, no studies have evaluated the efficacy of either substance. "Why not chose something that's been tested and shown to work?" Pollack says.

Insecticide Shampoos Can Be Toxic: "The only ones who should fear the proper use of these products are lice," says Pollack. Look for FDA-registered over-the-counter treatments containing pyrethrin, which is a natural chrysanthemum abstract, or permethrin, which is the synthetic form. If your lice appear to be resistant to those, the next step is a prescription shampoo containing either malathion or lindane. "When used properly, they are valuable and low-risk pesticides," Pollack says.

Manual Removal Is Safest: If you have short, straight hair, a special comb on its own could take care of an infestation. "If my daughter, who has thick, shoulder-length hair, had head lice, and I tried to use any of these devices on her, the neighbors would call the cops, it would cause so much discomfort and pain."

Editor's Note: Pollack has served as a paid scientific advisor in the past to companies that manufacture head lice shampoos.

Copyright 2023 NPR. To see more, visit https://www.npr.org.

Vikki Valentine
Vikki Valentine is a senior supervising editor on NPR's science desk. She oversees the network's health coverage across broadcast and digital platforms. Previously, Valentine was the network's climate change, energy, and environment editor and in this role was a recipient of a 2012 DuPont Award for coverage of natural gas drilling in Pennsylvania.