Pinworms

What are pinworms (pinworm infection)?

Pinworms, also called threadworms, are parasitic worms that live in the intestines and rectums of infected people — most commonly children. Pinworms are small and thin (about ¼ inch to ½ inch long), and white or light gray.

Pinworms are called Enterobius vermicularis. A pinworm infection is called enterobiasis.

Your child will need treatment if they have a pinworm infection. Luckily, pinworms don’t usually cause serious medical problems and are easy to cure.

How common are pinworm infections?

Enterobiasis is the most common type of worm infection in the United States. It affects approximately 40 million people in the U.S. and 1 billion people worldwide.

People of all ages can become infected with pinworms. Still, pinworm infections are most common in children, especially between ages 4 to 11. Rarely, adults get pinworms. Caregivers and family members of infected children have a higher risk of infection.

Pinworm infections pass easily from person to person in places where children are in close contact, including daycare centers, preschools and schools. People who live in institutions also commonly get infected.

What are the symptoms of a pinworm infection?

About a third of infected people don’t experience symptoms. Others experience intense itching near the anus (butthole), especially when they’re trying to sleep. Watch out for these symptoms, which may signal a pinworm infection:

• Anal itching, especially at night: Female pinworms lay eggs around your anus at night, causing itching and irritation. The itching can be severe.
• Vaginal itching: Pinworm eggs on the skin surrounding your vagina can cause itching and discharge.
• Sleeplessness: The itching can lead to restlessness and keep you (or your child) from a good night’s sleep. Sleep deprivation can make you tired during the day and have trouble concentrating.

How does a person get pinworms?

Pinworm infection occurs when your child swallows pinworm eggs. They become the host for the pinworm life cycle. While this may sound like something obvious to avoid, it’s easy to get infected. Here’s how it usually happens:

1. Pinworms lay their eggs on the skin around your child’s anus, sometimes causing itching.
2. When your child touches or scratches the area, the microscopic eggs (which are super sticky) attach to their fingers and get stuck beneath their fingernails.
3. Unless they wash their hands, your child transmits the eggs to other people and surfaces they touch.
4. When another person touches these surfaces and puts their fingers on their mouth, the eggs enter and travel through their digestive system. The eggs hatch in that person’s intestines.
5. Once hatched, the female pinworms travel to the person’s anus to lay their eggs, and the cycle restarts.

Each female worm can produce 10,000 or more eggs. Your child may have anywhere from a few worms to hundreds of them.

Can you get pinworms without being around an infected person?

Yes. Pinworm eggs can survive from two to three weeks on contaminated surfaces. You can get pinworms through:

• Bedsheets, underwear and towels. Eggs can spread through contact with contaminated sheets, towels or underwear.
• Toys. Children with pinworm infection can contaminate toys they share with other children at school or in daycare.
• Inhalation: The tiny eggs can rarely travel through the air. Once you breathe them in, the eggs travel through your digestive tract and hatch into pinworms that lay their own eggs. For example, shaking out your child’s bedding before you wash it can spread the eggs and put you at risk of infection.

Are pinworms contagious?

They’re highly contagious. Transmission is easy because the eggs can survive for a long time on surfaces or your fingers if you don’t wash your hands. The tiny eggs are microscopic. There’s no way to know you’re touching a contaminated surface or object. It’s easy to absentmindedly touch your fingers to your lips without knowing you’ve transferred pinworm eggs.

What are the complications associated with pinworms?

While serious complications are rare, pinworms can lead to:

• Bacterial infections: Scratching too much can break your skin, causing it to bleed and become infected.
• Urinary tract infections (UTIs): The worms can travel to your vagina, enter your urinary tract and cause infections.
• Gastrointestinal and abdominal problems: In rare cases, pinworms have been linked to appendicitis, diverticulitis (the growth of pouches in your large intestine), and inflammation of your vagina (vaginitis) and the lining of your uterus (endometritis).

How are pinworm infections diagnosed?

You’ll know you have a pinworm infection if you find signs of either the pinworm or the eggs. You can see adult pinworms with just your eyes, but your healthcare provider uses a microscope to see the eggs.

Checking for the worm

Check for pinworms about two to three hours after you fall asleep. Around this time, pinworms make their way out of your rectum to lay eggs around your anus. Pinworms look small, thin and grayish-white, like little pieces of thread. This is why they’re sometimes called threadworms.

You may also find them wriggling in underwear or bedsheets. If your child has many pinworms, they may appear in their stool (poop) or on toilet paper, but this is rare. It’s much easier to identify them on your child’s skin.

You can capture the worms using clear Scotch tape or just let your provider know you saw them.

Checking for the pinworm eggs

You can also use tape to collect the eggs. This is called the “tape test.” Here’s what you do:

1. Place a piece of clear tape (sticky side down) over your child’s anal area as soon as they wake up in the morning. The eggs will stick to the tape.
2. Take the tape to your child’s pediatrician, following their directions about how to safely share the sample. They’ll use a microscope to check for the eggs.

It’s best to do the tape test as soon as your child wakes, before bathing or using the bathroom. Both activities can remove the eggs from skin. You should do the tape test a few times (ideally, for three consecutive days) to get the most accurate results.

Your child’s pediatrician may also collect egg samples from underneath their fingernails.

How are pinworms treated?

Your child will need to take an oral (taken by mouth) anti-parasitic medication to kill the worms. They’ll take one dose immediately and another dose two weeks later to be sure all the worms are gone.

The medicines used to treat pinworms are:

• Pyrantel pamoate (the most common pinworm treatment, available without a prescription).
• Albendazole (available with a prescription).

Pediatricians recommend that an infected child’s family members and caregivers also get treated at the same time to reduce the risk of reinfection. Preventing reinfection is one of the biggest challenges in getting rid of pinworms.

Washing all clothing, bed linens and towels in as hot water as possible while taking the treatment can help reduce the risk of reinfection.

What are the side effects of treatment for pinworms?

Before using pyrantel pamoate, consult your doctor if you’re pregnant or your child is younger than 2 years old. Side effects of pyrantel pamoate include:

• Diarrhea.
• Nausea.
• Vomiting.
• Abdominal pain.
• Headache.

For all three medications, side effects include an upset stomach.

Do pinworms go away if they’re untreated?

No. Untreated pinworms lay more eggs, making it easier to spread the infection. Your child will need medicine to get rid of them.

What can I do to help relieve the symptoms of a pinworm infection?

Your child may still have itching after treatment for about a week. To relieve the itching, you can:

• Wash their anal area with warm water and soap.
• Use a 1% hydrocortisone cream on the skin around their anus.

How can I prevent pinworm infections?

The most effective way to prevent a pinworm infection (or reinfection) is by preventing the eggs from reaching your child’s (or your) mouth. Model good hygiene and the following practices for your child:

• Wash your hands often: Using soap and warm water, wash your hands after using the bathroom or changing a diaper. Wash your hands before handling food or touching your mouth or nose.
• Keep surfaces clean: Clean toys, counters, toilets, utensils, dishes and other surfaces frequently with soap and water to lower the risk of spreading the infection.
• Shower often: People with pinworms should shower daily to remove eggs from their skin. Avoid bathing since bathwater can become contaminated with eggs. People with pinworms shouldn’t bathe with others until the infection is gone.
• Care for your fingernails: To avoid transferring the eggs, keep your fingernails clean and trimmed. Work on quitting if you bite your nails.
• Avoid touching the anal area: Tell your child not to touch or scratch the affected area.
• Wash sheets, towels and underwear frequently: Wash linens, pajamas and underwear daily in hot water until the treatment is complete. Don’t shake out the laundry before washing since eggs can scatter and spread infection.

What is the prognosis (outlook) for people with pinworms?

Medications cure pinworms 90% to 100% of the time. With proper treatment, pinworms go away and don’t cause long-term health problems.

When should I call my doctor about pinworms?

If your child has anal itching at night, contact their pediatrician to see if it’s pinworms.

Children or families can have pinworm infections several times. If your child’s symptoms return after treatment, go back to their pediatrician. If you or another family member has symptoms, see a healthcare provider.