The most common type of worm infesting children, pinworms are essentially harmless. They are unpleasant to look at and may cause itching and, in girls, vaginal discharge, but they rarely cause more serious problems. Pinworms cause more social than medical problems in affected children and their families.

The adult worms are whitish-gray and threadlike, measuring about 1/4 to 1/2 inch long. You might see them on the skin around the anus, or you or your pediatrician might collect some of the worms and eggs by applying the sticky side of a strip of special cellophane tape to the skin around the anus. This then can be examined under a microscope to confirm the presence of the parasite.

Your child probably will become aware that she has pinworms at night, when the adult worms move from the rectum to the anus. This movement causes irritation and, sometimes, intense itching. If the worms crawl into the vaginal area, they may cause pain and a slight discharge. In many children, however, pinworms cause absolutely no discomfort, and may be detected only if the mature worms are seen while depositing their eggs.

Spread and Treatment of Pinworms

Pinworms spread easily from one child to another by the transfer of eggs. The mature pinworm, which lives in the intestinal tract and around the anal area, lays its eggs on the skin around the anus and buttocks. An infested child may get the tiny eggs on her hand when scratching the area or while wiping after a bowel movement, or the eggs may be left on the toilet seat, to be picked up by the next person who uses it. If the child does not wash the eggs off her hands, she may transfer them to her mouth or to other objects she touches, including the hands or mouth of another person.

Another child picks up the eggs by touching the infested child's hands or objects she handled. She then transfers them to her own mouth by putting her hands in her mouth or mouthing contaminated material.

After the eggs are swallowed, they remain in the small intestine until they hatch, and the small worms travel to the end of the intestine, where they mature and mate. The female then deposits eggs around the anus, and the 35-day life cycle is ready to be repeated. If the new eggs are not ingested; however, the infestation ends at this time.


Pinworms can be treated easily with an oral prescription, taken in a single dose and then repeated in one to two weeks. This medication causes the mature pinworms to be expelled through the bowel movements. Some pediatricians may recommend treating the other family members as well, since one of them may be a carrier without having any symptoms.

Preventing Pinworms

It is very difficult to prevent pinworms, but here are some hints that might be helpful.

  • Encourage your child to wash her hands after using the bathroom.
  • Encourage her sitter or day-care provider to wash the toys frequently, particularly if pinworms have been detected in one or more of the children.
  • Encourage your child to wash her hands after playing with a house cat or dog, since these pets can carry the eggs in their fur.

Caring for Baby and Young Child: Birth to Age 5, Bantam 1999
© Copyright 2000 American Academy of Pediatrics