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Pinworms: Everything you need to know

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What are pinworms?SymptomsCausesDiagnosisTreatmentsSummary
Pinworms are small parasites that live in the intestines and lay eggs around the anus, causing intense itching. Learn more about how to treat the infection and how to prevent it. 
Medically reviewed by Madeline Knott, MD
Written by Suan Pineda
Updated on

Pinworms are small parasites whose eggs, when ingested, can cause an infection. Pinworm infections are a common worm infection in the United States and primarily affect children.

Pinworms are also known as “butt worms” because of the area they affect. The most common symptom of a pinworm infection is strong itching around the anus. 

But there are treatments available. Learning more about identifying and treating these butt worms can help you feel better as soon as possible.

What are butt worms?

A young child with pinworms or butt worms playing with toy dinosaurs on the floor
Photography by Catherine Delahaye/Getty Images

Pinworms, or Enterobius vermicularis, are a type of nematode or roundworm whose tail (particularly in female pinworms) is the shape of a pin. 

Pinworms live in a person’s intestines and colon. When females are ready to lay their eggs, they come out through the rectum and lay their eggs around the anus. These eggs can survive for 2–3 weeks. For the eggs to hatch, a person needs to ingest them orally. The eggs hatch in the intestines. 

Pinworm infections are common among children and young people under age 18 years. Roughly 50% of people in this group have had a pinworm infection. This is because pinworm infections spread easily among members of this group — particularly young children.

Pinworm eggs can spread between people when a person with pinworms doesn’t wash their hands after going to the bathroom.

The tiny pinworm eggs remain on their hands and transfer to surfaces they touch, like tables, doorknobs, and chairs. Another person who then touches these surfaces can pick up the pinworm eggs and ingest them when they take their hands to their mouth. The pinworm then hatches inside their intestines. 

People can also transfer pinworms by sharing clothes or bedding with someone who has them.

When pinworms are ready to lay eggs, the female pinworm leaves the intestine to do so around the anus. This happens usually when the person is sleeping. The presence of pinworms on the skin that surrounds the rectum and the anus, or even the vagina in some people, leads to uncomfortable and bothersome symptoms.


The common symptoms of a pinworm infection include:

  • intense itching in the anal area or around the vagina
  • worms in the poop, which tend to look like small white threads
  • restlessness and difficulty sleeping
  • irritability

Pinworm infections can lead to less common symptoms like vomiting and weight loss, bed wetting (particularly in children), and irritation in the skin around the anus. 


The causes of a pinworm infection usually have to do with poor hygiene. People with an active infection can pass pinworms by touching their anal or vaginal area and then touching surfaces that other people touch. This is why handwashing and other hygiene practices are key to preventing the spread of infection.

To help prevent passing or getting a pinworm infection, you can try:

  • washing your hands with soap and water after going to the toilet or changing diapers
  • taking a shower every day
  • changing and washing underwear frequently
  • changing and washing bed sheets frequently because the pinworm eggs can lie in bed linens
  • cleaning commonly touched surfaces
  • keeping fingernails short and clean


Doctors will consider your symptoms before testing for pinworms. If you have itching around your anus at night, this is very indicative that you have them.

Doctors may use a tape test to diagnose pinworms. This test involves pressing a small piece of clear tape to the skin around the anus. Pinworm eggs will stick to the tape, and the doctor can examine them under a microscope to confirm what they are.


To treat a pinworm infection, healthcare professionals may recommend over-the-counter (OTC) or prescription medications, depending on the severity of the infection.

Some of these treatments and medications include:

  • OTC pinworm medication: You can get pyrantel pamoate (Reese’s Pinworm Medicine) over the counter. Pyrantel pamoate is an antiworm medication that comes in capsule or liquid form. You take one dose and then repeat after 2 weeks
  • Prescription medication: Albendazole (Albenza) and mebendazole (Vermox) work by killing the pinworms. These medications come as tablets. Follow your healthcare professional’s and pharmacist’s instructions on dosage and how to take these medications. 
  • Home remedies: The evidence for home remedies to address a pinworm infection is anecdotal, and there are no scientific studies to confirm their effectiveness.

Research suggests it’s important for everyone in the household to receive treatment. This helps prevent reinfection, as pinworms are very transmissible and can quickly spread through a household.

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Pinworms are small parasites that live in your intestines. They’re small, white worms with tails the shape of a pin. Female pinworms exit the intestines through the rectum to lay their eggs. They leave these eggs in the skin surrounding the anus. 

This is why pinworms are also known as butt worms. A pinworm infection causes intense itching in the anal and vaginal area. It can lead to restlessness and irritability at night when the worms usually come out to lay their eggs. 

Pinworm infections are common among children. A person with a pinworm infection can transmit the eggs if they don’t wash their hands after going to the bathroom and touch common surfaces like a table, chairs, or toys.

If another person touches these surfaces and then takes their hands to their mouth, they may swallow the eggs. The pinworm eggs hatch in your intestines, and the worms live there. 

You may notice a pinworm infection when you see short white threads in your poop — these are the worms. 

A healthcare professional may recommend OTC or prescription medications to treat the infection. They will also recommend preventive measures like handwashing, showering, and frequent changing and washing of underwear and bed linens. 

Download the free Optum Perks Discount Card to save up to 80% on some prescription medications.

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