Pinworm Infection

Medically Reviewed by Jennifer Robinson, MD on September 02, 2022
4 min read

A pinworm infection is an intestinal illness that’s very common in elementary school-aged children. Pinworms are small, thin, pin-shaped worms that sometimes live in the human colon and rectum. They’re 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 you sleep: They leave the intestine through your anus and deposit their eggs on the surrounding skin.

Most people who are infected don’t have symptoms. If you do, they might include:

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

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

You get pinworms 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 swallow the eggs.

About a month later, the eggs hatch in your intestines and grow into adult worms. Female pinworms move to your anal 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. It’s very easy to spread a pinworm infection. 

Anyone can get a pinworm infection. It’s the most common kind of worm infection in the United States. But it’s more likely if:

  • You’re between the ages of 5-10. 
  • You live with or take care of small children.
  • You live in a crowded space, like a hospital or jail. 
  • You suck your thumb or bite your nails.
  • You don’t wash your hands.

If you, your child, or someone in your household has symptoms of pinworm infection, call the 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 wakes 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 3 days in a row, then take all the pieces of tape to your doctor. They’ll look at them under a microscope to check for the eggs.

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

  • Albendazole (Albenza)
  • Mebendazole (Emverm)
  • Pyrantel pamoate (Reese’s Pinworm Medication, Pin-X). Available over the counter.

You may need to take at least two doses to get rid of the worms completely. The medicine might upset your stomach a little.

The doctor may prescribe medication to everyone in your household to prevent infection and reinfection. For best results, treat the infected person and everyone in your house (including caretakers) at the same time.

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. 

Other rare complications include:

  • Bacterial infection from scratching the anal area
  • Urinary tract infection (UTI)
  • Appendicitis
  • Abdominal infection
  • Weight loss

Pinworm eggs can live on hard surfaces and in clothes and bedding for 2 to 3 weeks. In addition to your regular household cleaning, you’ll want to take these steps to stop the spread:

  • 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 recontamination in bath water.
  • Don’t bathe with anyone or share towels during treatment and for 2 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.