Among parenting nightmares, discovering a child has lice ranks way up there. 

What is it about lice that makes them so loathsome? They aren't dangerous. They don't carry or spread disease. They don't even fly. All they do is feed on tiny amounts of blood. But they are tenacious. Lice can survive for up to 30 days on a kid's scalp and lay as many as eight eggs a day. They're gross, all right.

Close-nit family and friends

According to the Centers for Disease Control and Prevention (CDC), lice get around through head-to-head contact — typically when a kid hugs or leans in close to a sibling or pal whose scalp is infested. 

Lice also can infest upholstered furniture, hoodies, hats and caps, hairbrushes and backpacks, pillows and even stuffed animals. Obviously it's not a good idea for children to share these things, but borrowing a brush isn't the only way a kid can catch lice: Since the critters are such fast crawlers, they easily can spread through a pile of backpacks or jackets piled together. 

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Signs of lice

Relentless head-scratching usually is the first clue a kid has lice. The sensation could be a tickley feeling from lice crawling around or an allergic reaction to lice bites. Lice are most active at night, so an infested kid may have trouble sleeping. If she scratches a lot, she can develop red sores or a rash on her scalp, according to the CDC. 

Related: What Your Hair Says About Your Health

To check a child for lice, have him sit with a bright light focused on his head. Using a magnifying glass if you need to, inspect his scalp, paying close attention just behind his ears and the nape of his neck. 

What to look for:

  • Adult lice are tan or grey-ish white, about the size of a sesame seed and move around. 
  • Lice eggs (nits) and newborn lice (nymphs) are smaller, about the size of strawberry seeds, and brown, yellow or tan. They cling to hair, usually no more than a quarter of an inch from the scalp. Nits look a lot like dandruff, so the best way to "test" for them is to run a strand of hair between your thumb and forefinger. A dandruff flake will fall away. A nit or nymph will hold on for dear life. 

If you can't tell if your child has lice, have your pediatrician or the school nurse check her. 

The abc's of de-licing

If your kid does indeed bring lice into your household, take these steps to get rid of them. 

Reassure your child. No matter how grossed out you might be, don't let it show. Tell her it's not her fault she has lice. (But do remind her that going forward it's not a good idea to share hats or caps with other kids.)

Check every head in the household. If other kids (or adults) have lice, you'll want to make treatment a family affair. Have an older child or your spouse check you too.

Wash, dry and repeat. Wash your children’s clothes, sheets, caps, scarves, washable stuffed toys and pillows in a hot wash. Dry them on a hot setting for 10 minutes. Seal delicate clothing and plush toys that can't go into the washing machine in plastic bags and leave them there for three days to two weeks. You may want to change and wash pillows and sheets every day until the lice are gone.

Soak combs and brushes. Leaving them in 130 degree F water for 10 minutes will kill lice and nits.

Suck it up. Vacuum floor, carpets and furniture to catch nit-infested stray hairs. Skip lice fumigant sprays. 

Wash those pests right out of his hair. Your first line of treatment should be an over-the-counter medicated shampoo that contains one percent permethrin, advises the American Academy of Pediatrics. (AAP).

"Permethrin is a synthetic form of pyrethrin, which comes from chrysanthemum flowers," explains James Cuthbertson, MD, of Berkeley Pediatrics. "It's a neurotoxin to lice — it poisons their nervous systems — but doesn't harm humans."

Read before you suds up. Most lice shampoos are designed to be left on hair for at least 10 minutes, but different strengths or forms may have different procedures. Shampooing too much or too often can be harmful. On the other hand, using too little shampoo may not get rid of the critters.

Also some lice shampoos aren't safe for young children, and no medicated treatment is safe for babies under 2 months.

Comb out the critters. After you've shampooed and rinsed you'll literally need to go over your child's scalp with a fine-toothed comb: Using a special lice, or nit, comb (it will have tiny close-set tines), comb out a few strands of hair at a time. Start at the roots of each section and pull the comb all the way to the ends. Rinse the comb in a glass of water and wipe it dry with a paper towel each time. This can take some time: You might want to do it in front of a movie. 

Hold off on your regular shampoos. If you're planning to use a lice treatment, don't wash or condition hair first, advises the CDC. According to the American Academy of Dermatology (AAD), you should wait at least two days after treatment to use regular hair products. 

Keep on combing. Use the lice comb every day for two or three weeks. The AAD says banished lice have a nasty habit of moving back in. 

Do the follow-up treatment. Most lice shampoos require a second application seven to nine days after the first to prevent any lice eggs you missed with the comb from hatching. 

In some areas, lice have developed a tolerance for over-the-counter lice shampoos. If lice are still lively eight to 10 hours after home treatment, see your doctor for a prescription lice medication or consider calling a professional lice-remover. Some make house-calls. 

Warning: If your doctor has prescribed the lice medication Ovide (malathion lotion) note it isn't safe for infants, nor has it been proven safe for children under 6. It's highly flammable, so the CDC warns against using a hairdryer or curling iron on hair that's just been treated with malathion. In fact, adds the AAD, never use the lotion in a room with an open flame or near a heat-producing appliance like an iron or space heater. Certainly don't light up around malathion, and keep it well out of reach of little kids: If a child drinks it, it could affect her breathing. 

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Do home remedies work?

Some people favor home treatments like putting petroleum jelly in hair for an hour or two and then washing it out (Vaseline kills some lice eggs, but not enough), according to the Journal of Pediatric Nursing. Nor will a long shower or bath drown lice: They can survive in water for up to eight hours. And of course, you should never use gasoline, kerosene or home pest sprays for head lice.

The easiest way to give head bugs the boot, say experts, is the old-fashioned way: If your child is willing, have his hair cut stylishly short or even give him a buzz cut. A few minutes with scissors or an electric shaver is certainly easier than an hour or more every day combing out nits. 

Ana Manley-Black, J.D., is a former immigration attorney and a freelance health and medical writer whose stories have appeared in Healthday, Consumer Health Interactive, and other media.