Pinworms, also known as threadworms, are tiny white or light gray worms that cause the common infection called enterobiasis. Usually found in children, pinworm can be treated with anti-parasitic medications that do not require a prescription.
Pinworms, also called threadworms, are parasitic worms that live in the intestines and rectums of infected people. Pinworms are small and thin (about ¼ inch to ½ inch long), and white or light gray.
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The pinworm infection is called enterobiasis. It is the most common type of worm infection in the United States. Although a pinworm infection does need to be treated, it usually doesn’t cause any serious medical problems.
Pinworm infections are very common, affecting approximately 1 billion people worldwide.
People of all ages can become infected with pinworms, but the infections are found most often in children. Caregivers and family members of infected children have a higher risk of infection.
Day care centers, preschools, and schools are often the source of a pinworm infection. People who live in institutions are also commonly affected by pinworms.
Symptoms of a pinworm infection (enterobiasis) include:
Pinworm infection occurs when someone swallows pinworm eggs, usually in the following manner:
Pinworm eggs can survive for 2-3 weeks on fingers, under fingernails, and on surfaces such as linens, clothing or toilet seats. The tiny eggs can only be seen under a microscope.
Yes. A pinworm infection can also be spread through:
If you or your child has anal itching that is worse at night, it’s important to see a doctor. Your doctor will ask about your symptoms, especially anal itching at night. In addition, the doctor may ask you to collect the pinworm eggs using the “tape test.” To do this:
It’s best to do the tape test as soon as the person wakes up, before bathing or using the bathroom. You should do the tape test a few times to get the most accurate results.
Another way to confirm a diagnosis is to see the pinworms. While the infected person is sleeping, mature pinworms make their way out of the rectum to lay their eggs around the anal opening.
Small, thin, grayish-white worms may be visible around the anus two-three hours after the person falls asleep. The worms look like little pieces of thread, which is why they are sometimes called threadworm. You can capture the worms using clear tape or let your doctor know that you saw them.
Pinworms are treated with an oral (taken by mouth) anti-parasitic medication that kills the worms. You will need to take one dose right away and another dose two weeks later to make sure all the worms are gone. To reduce the risk of re-infection, pediatricians recommend that the family members and caregivers of an infected child be treated, as well.
The medications used to treat pinworms are:
Pyrantel pamoate is the medication most commonly used to treat pinworms. It is available without a prescription (over-the-counter).
Before using pyrantel pamoate, you should consult your doctor if you are pregnant or if the infected child is younger than 2 years old. Side effects of pyrantel pamoate include:
For all three medications, side effects include gastrointestinal upset.
While serious complications are rare, pinworms can lead to:
To relieve the itching, you can:
The most effective way to prevent a pinworm infection is by practicing cleanliness in the following ways:
With proper treatment, pinworms don’t cause long-term health problems. Children or families can have pinworm infections several times. If the symptoms return after treatment, you should go back to your doctor.
If you or your child has anal itching that is worse at night, you should contact your doctor or your child’s pediatrician.
Last reviewed by a Cleveland Clinic medical professional on 07/19/2019.
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