Dermatology • Apr 21, 2015

That anal itch: how to diagnose and permanently get rid of pinworms

MoodyKidThat mom’s face said it all– her expression changed from worried to grossed-out as I showed her the squiggling worm protruding from her daughter’s anus under the bright light of my examining room.  She had brought her toddler to the emergency room because she was awakening in the night and scratching her bottom and complaining of rectal itch.  Could it be sexual abuse, she asked?  No, I reassured her, just pinworms. 

An estimated 20-40% of American children carry pinworms at any given time.  They are also known as threadworm, or enterobius vermicularis.  They are ubiquitous in our community and anyone can catch them.  Pinworms live in the digestive tract and especially the anus.  Pinworms can also infest the vagina in females.  The best prevention is strict hygiene, but let’s face it, what toddler has perfect hygiene?  If your child is a nail biter or thumb sucker, it’s nearly impossible to prevent pinworms.  And once pinworms are in your house, they often spread to the entire family, including parents.

Here’s the good news: pinworms are easily treated with either over-the-counter or prescription medications.  Before you rush off to Walgreens to buy Reece’s Pinworm Medicine or Pin-X, make sure you really have pinworms.  It’s easy to diagnose at home, and these tricks work for grown-ups, too.

How to tell if your child has pinworms: If your child is complaining of anal itching, especially at night, check on them in their bed about 2-3 hours after they fall asleep.  Pick a night when they didn’t have a bath, if possible.  Bring a good flashlight, and have your child lay on their belly with their buttocks in the air.  Spread the butt cheeks and get a good look at the anus.  Ask your child to push out like they are having a bowel movement while you are looking, which will help expose the anus.

Look carefully for one or more white worms about 4-12 mm long and about as thick as a piece of white thread or dental floss.  If you see it move, it’s a worm.  Click here to see a picture of a pinworm. Pick up the worm with a piece of scotch tape (the transparent kind) so that you can prove your diagnosis to your physician, your child, or anyone else who doesn’t want to believe the ugly truth of pinworms.  If you don’t see anything, or if you’re not sure what you’re looking at, just apply a piece of scotch tape to the anal area, crossing from about 2 cm on one side of the anus to about 2 cm on the other side of the anus.  Press firmly, then stick the tape to a glass microscope slide, sticky side down.  If you don’t have a glass slide, you can get one from your physician.  The pinworm eggs will stick to the tape and your doctor will be able to see them under a microscope, diagnosing the pinworms.  This is called the “scotch tape test.”

How to treat pinworms at home without a prescription: If you found a worm and saw it move, you probably don’t need to see your physician.  Pinworms can usually be treated completely with two doses of over-the-counter medicine called pyrantel pamoate, available in the United States under the brand names Pin-X and Reese’s Pinworm Medicine.  Take one dose immediately and another dose two weeks later.  If you are having persistent symptoms (anal pain, abdominal pain, blood in stool, or rectal bleeding), be sure to seek medical care immediately.

What prescription medications are used for pinworms?  Mebendazole, also called Vermox, is a prescription medication that very effectively kills pinworms.  As of December, 2011, mebendazole is no longer available from any manufacturer in the USA, although it can be made by compounding pharmacies with a doctor’s prescription. No reason was given publicly for this discontinuation in the United States.  Mebendazole is still available internationally and is recommended by the World Health Association as an essential medication for a basic medical system.

If one member of your household has pinworms, you need to treat your entire family.  You may need to treat your pets, too (ask your vet).  Pinworms lay eggs that are easily spread to children (and adults) who touch their anal area and then don’t wash their hands and fingernails well.  Many (if not most) people with pinworms have no symptoms, so the person who keeps spreading the eggs around your house may not be the person with symptoms.  It’s a bit painful to buy medicine for the whole household and get your kids to take it, but you’ll be glad when you don’t have a recurrence in a few months.

Can infants get pinworms? Yes, but it is uncommon. Infants who are not yet crawling, drinking water, or eating solid food probably will not ingest the pinworm eggs and, hence, are unlikely to contract the illness.  Rarely pinworm eggs can be inhaled, which is a potential mechanism of infant infection.  Infants generally have a very clean anal area because their caregivers wipe their anus with baby wipes with every diaper change, making re-infection unlikely.  Once an infant starts crawling and putting things in their mouth, they are at risk of pinworms.

What is the treatment for pinworms during pregnancy?  Pinworms are common in pregnancy, as many expectant moms also have pinworm-laden toddlers in the house.  Pinworms cannot hurt or infect a baby before birth, but they are uncomfortable and just plain disgusting for a pregnant mother.  Sadly, neither pyrantel pamoate nor mebendazole is recommended during either pregnancy or breastfeeding.  Breastfeeding mothers can take either medication if they “pump and dump” afterwards.  The good news is that pinworms can still be eradicated during pregnancy (or breastfeeding) using the strict hygiene approach to treatment (see below).  Some people also recommend enemas for flushing the pinworm eggs out of the rectum, although I have not found any research that supports this treatment.  The lack of research doesn’t mean this approach doesn’t work– a study to show effectiveness would be very hard to do.

Prevention– how to keep the pinworms out of your home: Strict hygiene measures can clear up pinworm infection without medication, and reduce the risk of reinfection. The worm has a lifespan of about six weeks, therefore the strict hygiene needs to last that long. Everyone in the household has to adhere to strict hygiene, which can be very hard if you have a nail-biter or thumb sucker.  But do the best you can and take advantage of the opportunity to motivate your children to improve their hygiene.

  • Wash all bed linen, pajamas, and anything your child sleeps with.
  • Vacuum your carpets and mop your floors regularly (at least weekly).  Clean every floor in your whole house, especially bedrooms and bathrooms.  Your goal is to get the eggs out of your carpets and off your floors.  Pinworm eggs can live 2-3 weeks outside the body.
  • Clean surfaces in the kitchen and bathroom daily, especially faucet knobs and the toilet flush handle.  Use Clorox wipes or a rag with hot water.
  • Do not shake things that may have eggs on them, such as clothing, underwear, pajamas, bed linen or towels.
  • Do not eat in the bedroom. There is a risk of swallowing eggs that have shaken off the bed linen.
  • Make sure everybody’s fingernails are cut short.  Teach children to wash under their nails with a nail brush daily.  If you have a nail biter or finger sucker, consider this a motivational opportunity to quit.
  • Teach children to wash hands thoroughly after going to the bathroom and before eating.  Sing “Happy Birthday to You” and don’t quit scrubbing your hands and nails until the song is done.
  • Always wear tight-fitting underwear (not boxer shorts).  Change your underwear every morning.
  • Cotton gloves may help prevent scratching during sleep.
  • Everyone in the household needs a bath or shower daily.  Teach your children to thoroughly soap up and rinse their rectum and genital areas.
  • Do not share towels or washcloths.  Wash bath towels and washcloths after each use.  Change hand towels daily.
  • Airborne eggs can theoretically land on your toothbrush.  Keep toothbrushes in a closed cabinet and/or rinse them well before each use.

Watch the “pinworm movie” with your kids and learn the pinworm lifecycle:  Understanding these nasty creatures, their mating cycles, and how they lay eggs will motivate you and your kids to improve your hygiene.  There is a great YouTube video on the enterobius lifecycle here.  Watch it together as a family, then smile while your kids wash their hands and start cleaning.

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