What Are Pinworms? How Do You Get Infected?

Pinworms are small, thin, pin-shaped worms that sometimes live in the human colon and rectum. They are also called threadworms. They’re about one-quarter to one-half inch long -- about the size of a staple. The females do their work while an infected person sleeps: They leave the intestine through the anus and deposit their eggs on the surrounding skin.

How Do You Get Them?

By accidentally swallowing or breathing in their eggs. You could eat or drink something that’s contaminated with them and not know it. The eggs can also live on surfaces like clothing, bedding, or other objects. If you touch one of these items and then put your fingers in your mouth, you’ll ingest the eggs.

About a month later, the eggs hatch in your intestines and mature into adult worms. Female pinworms move to your anus area to lay their eggs. This causes anal itching. If you scratch the area, the eggs cling to your fingers and get under your nails. If you touch other surfaces or objects, you could spread the worms.

Are They Contagious?

Yes. Pinworm infection occurs most often in school-aged children. It’s also easily spread to family members and caregivers.

People who live in crowded spaces, like institutions, have a higher risk of getting pinworm infections.

What Are the Symptoms?

Most people who are infected don’t have any. If you do, they might include any of the following:

  • Anal itching, especially at night
  • Restless sleep
  • Itching of the vaginal area -- if adult worms move to the vagina
  • Feeling irritable
  • Abdominal pain that comes and goes

Talk to your doctor if you have severe anal itching -- especially at night.

Most of the time, pinworm infections don’t cause serious problems. In rare cases, and especially if you have a lot of them, the pinworms can travel from the anal area up the vagina to the uterus, fallopian tubes, and around the pelvic organs. This can cause inflammation of the vagina -- what doctors call vulvovaginitis.

Tape Test

If you, your child, or someone in your household has symptoms of pinworm infection, call your doctor and ask about the tape test. Simply take a clear piece of tape and press the sticky side to the skin around the anus. Do this as soon as you or your child wake up -- before you use the bathroom, shower, or get dressed. The pinworm eggs will stick to the tape.

You’ll need to repeat this test three days in a row, then take all the pieces of tape to your doctor. He’ll view them under a microscope.


What's the Treatment for Pinworm Infection?

You’ll need to take medications that kill the worms.

Your doctor may recommend an over-the-counter treatment like pyrantel pamoate (Reese’s Pinworm Medication, Pin-X). He might also prescribe medication to everyone in your household to prevent infection and re-infection.

The most common prescription medicine for pinworms is albendazole (Albenza). You might have mild stomach upset while you’re taking it. And, you may need to take at least two doses to get rid of the worms completely.

For best results, the infected person and everyone in your house (including caretakers) should be treated at the same time.

How Can I Prevent Pinworms?

Pinworm eggs can live on hard surfaces and in clothes and bedding for two to three weeks. In addition to your regular household cleaning, you’ll want to do the following things to stop the spread of these pests:

  • Pinworms lay their eggs at night. Wash your anal area in the morning to reduce the number of eggs on your body. Shower to prevent possible re-contamination in bath water.
  • Don’t bathe with anyone or share towels during treatment and for two weeks after final treatment.
  • Change your underwear and bed linens each day. This helps remove eggs.
  • Wash bedsheets, nightclothes, underwear, washcloths, and towels in hot water to kill pinworm eggs. Dry them on high heat.
  • Don’t scratch your anal area. Trim your child’s nails so there’s less space for eggs to collect. Discourage nail biting.
  • Wash your hands with soap and water after using the bathroom, changing diapers, and before handling food. Teach your kids to do the same.
WebMD Medical Reference Reviewed by Sabrina Felson, MD on October 26, 2018



Mayo Clinic: “Pinworm Infection.”

CDC: “Pinworm Infection FAQs.”

HealthyChildren.org.: “Pinworms.”

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