The Lifecycle of a Pinworm

Lifecycle of a PinwormUnless your child has experienced them, you’ve probably never heard of pinworms. But pinworms are actually the most common intestinal parasite in the United States. If your family is currently facing a pinworm infection, you are likely looking for all the information you can find related to these tiny intestinal parasites.

Wondering just how your family ended up with pinworms? A quick breakdown of the lifecycle of a pinworm shows you just how random contracting a pinworm infection is.

Pinworms can happen to any family. And gross as it is, the process typically starts with the ingestion of pinworm eggs.


The lifecycle of the pinwom begins with microscopic pinworm eggs. Able to survive on most surfaces for 2 to 3 weeks, pinworms can be picked up anywhere.  Due in part to their not-so-hygienic tendencies, school-age and preschool children are some of those most likely to get a pinworm infection.


After pinworm eggs are ingested, they travel through the stomach to the large intestine. Along the route, eggs hatch and reach sexual maturity. Adult female pinworms then migrate from the large intestine to the anal area, where new eggs are laid.

The egg-laying process typically happens in the middle of the night or early in the morning, which is why we recommend performing the “Scotch® Tape Test” after your child has gone to bed. It’s the best time to catch the little pests!

Adult pinworms look similar to a piece of thread. They are white in color and measure about 1/2” in length.


Retroinfection occurs when the eggs that are deposited on the perianal skin hatch. These juvenile pinworms will crawl back into the anus and mature into adults, allowing the process to repeat itself. It takes just 6 hours for these eggs to mature and become infective.


Of course, with tiny worms crawling in their behinds, it’s easy to understand why children infected with pinworms will start to scratch. And once they do, the contamination process begins again. Hands, underwear, pajamas, bedding and any surface your child touches after scratching their behind can easily become home to the microscopic pinworm eggs.

The contamination stage of the pinworm’s lifecycle is the one that parents can take precautions to avoid after their family has been treated with Reese’s Pinworm Medicine. Also, Reese’s Pinworm Itch Relief Wipes can help soothe the itch while waiting for the medicine to take effect. Trim fingernails short, remind your family members to wash their hands frequently, and take proper steps to clean pinworms out of your home.

For more information on cleaning after a pinworm infection, read our blog post titled: How Do You Get Rid of Pinworms in Your Home?