Pinworm Infection

(Enterobiasis; Oxyuriasis)

Reviewed/Revised Jul 2023
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What is pinworm infection?

Pinworms are parasites that usually infect children, though adults can get them too. The pinworms live in the intestine and lay their eggs in the skin around the anus (opening where stool [poop] comes out), causing itching.

  • Itching around the anus is a symptom of pinworms

  • Children who suck their thumbs have a greater risk of getting pinworms because they're more likely to swallow pinworm eggs

  • If you suspect your child has pinworms, you may be able to spot the worms by looking with a flashlight around your child's anus at night—they are small, white, and wriggly

  • Doctors treat pinworms with an antiparasite medicine

What causes pinworm infection?

Pinworm infection is caused by tiny worms that get in your intestines.

  • You get the infection by swallowing tiny pinworm eggs

  • The eggs hatch and grow in your intestine

  • About 2 to 6 weeks later, the adult pinworms come out of your anus and lay their microscopic eggs on the skin nearby

  • You can pass the eggs to other people

The eggs make your anus itch. When you scratch, you get the pinworm eggs under your fingernails and can spread them to other people. The eggs also get on your bedsheets and can infect people. Pinworms are more common in children because they don't wash their hands as much as adults.

What are the symptoms of pinworm infection?

Many people who carry pinworms have no symptoms. If you have symptoms, they may include:

  • Itchiness in the area around the anus

  • In girls, itchiness and irritation around the vagina

How can doctors tell if I have pinworm infection?

If doctors think your child may have pinworms, they usually ask you to look for pinworms or their eggs.

  • Check for adult pinworms around your child's anus about 1 or 2 hours after your child goes to sleep—the pinworms are white, wriggly, and hair-thin, but you can see them with your naked eye

  • Pat a sticky strip of tape around your child's anus first thing in the morning to pick up any eggs—take the tape to your doctor's office to be looked at under a microscope

How do doctors treat pinworm infection?

Doctors treat pinworm infection with:

  • Antiparasite medicine—usually, you take a dose right away, and another dose 2 weeks later 

  • Sometimes, antiparasite medicine for everyone in your family so the pinworms don’t spread

  • An anti-itching cream to use on or around the anus

To get rid of pinworm eggs in your house after an infection:

  • Carefully vacuum your entire house

  • Wash everything the infected person touched, such as toys, bed sheets, and clothes

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