Am Fam Physician. 2019;99(10):online
See related article on lice and scabies
What are lice and scabies?
Lice are small parasites (bugs) that live on hair-covered skin. They are often connected to the base of the hair on the scalp or in the pubic area. When you have lice, it is called pediculosis (say: puh-DIK-yuh-LOW-sis).
Scabies is caused by tiny bugs called mites. They dig under the skin. Lice and scabies both cause itching.
How do I know if I have lice or scabies?
If you itch on your head or other hairy parts of your body, and the itching happens at all times of day, it could be lice. Scabies happens on the body but usually not on the head or neck area. Itching with scabies is severe and often worse at night.
If you think you or your child might have lice, look at the scalp closely. Lice are hard to see. It is best to use a bright light and look for the lice eggs (also called nits). Nits are yellow to white in color. They will be attached to the bottom of the hair next to the scalp, often behind the ears or on the neck. Having nits does not mean you have active lice. If you find a crawling louse, then you have active lice.
Scabies mites are too small to see, but you can see the rash they cause. The mites usually dig into the skin between the fingers or around the ankles, wrists, arm pits, groin, and belt line. You may see wavy, red, raised lines on the skin where the mites dig in. Most often, you will see small, red, raised bumps with scratch marks.
How are lice treated?
Treatment is only needed if you see live, crawling lice. Lice can be killed with medicated lotions and shampoos that you can buy over the counter. Two brands are Nix and Rid. Follow the directions carefully. Rid should be put on dry hair at the scalp. Nix should be put on damp hair at the scalp. Both should be left on for 10 minutes and then rinsed out. Repeat after seven days. Children should not be kept out of school during treatment, and especially not when only nits are visible.
You can also comb the hair with a nit comb. This is a special fine-toothed comb that removes lice eggs. You can comb more than once, but do not treat again for at least seven days. Nits are sometimes found in the hair for a few weeks after treatment. This does not mean that you need more treatment.
To keep from getting lice again, items that have touched your head during the two days before you started treatment, like pillowcases, hats, and clothing, should be washed in very hot water. Dry them in the dryer using high heat. Items that cannot be washed should be sealed in an airtight plastic bag for two weeks to kill the lice. Don't use chemical sprays.
How is scabies treated?
See your doctor right away if you think you have scabies. Your doctor can prescribe a cream to kill the mites. You will put the cream on your body from the neck down. Make sure to follow the directions carefully. You should keep the cream on overnight for eight to 14 hours, and then wash it off. Your close contacts (family members and sex partners) also should be treated at the same time so that the scabies aren't spread to them.
Bedding, towels, and clothing should be washed in very hot water and dried using high heat. Items that cannot be washed should be sealed in an airtight plastic bag for one week. Do not use chemical sprays or powders because they are not helpful.
Can lice or scabies cause other problems?
Lice and scabies do not go away without treatment. The lice and mites do not carry harmful diseases and can't make you sick. But, germs can get into your skin from too much scratching.
What if the treatment doesn't work?
You might keep itching for a while even after treating lice or scabies. But, treatments sometimes don't work even when used correctly. Talk to your doctor if the problem does not go away after two treatments.
Where can I get more information?
AAFP's Patient Information Resource
Centers for Disease Control and Prevention