Pinworms are small parasites that can live in the colon and rectum. You get them when you swallow their eggs. The eggs hatch inside your intestines. While you sleep, the female pinworms leave the intestines through the anus and lay eggs on nearby skin.

Pinworms spread easily. When people who are infected touch their anus, the eggs attach to their fingertips. They can spread the eggs to others directly through their hands, or through contaminated clothing, bedding, food, or other articles. The eggs can live on household surfaces for up to 2 weeks.

The infection is more common in children. Many people have no symptoms at all. Some people feel itching around the anus or vagina. The itching may become intense, interfere with sleep, and make you irritable.

Your health care provider can diagnose pinworm infection by finding the eggs. A common way to collect the eggs is with a sticky piece of clear tape. Mild infections may not need treatment. If you do need medicine, everyone in the household should take it.

To prevent becoming infected or reinfected with pinworms:

• Bathe after waking up
• Wash your pajamas and bed sheets often
• Wash your hands regularly, especially after using the bathroom or changing diapers
• Change your underwear every day
• Avoid nail biting
• Avoid scratching the anal area

NIH: National Institute of Allergy and Infectious Diseases