Alternative names
Enterobiasis; Oxyuriasis

Pinworms are small worms that infect the intestines. They are common in children and easy to treat.

Causes, incidence, and risk factors

Pinworms are the most common worm infection in the United States, primarily affecting school-age children. Pinworm eggs are spread directly from person to person or by touching bedding, food, or other items contaminated with the eggs.

Typically, children unknowingly touch the eggs and puts their fingers in their mouth. The eggs are swallowed. The eggs eventually hatch in the small intestine and worms mature in the colon. Female worms then move to the child’s anal area, especially at night, and deposit more eggs. This may cause intense itching and the area may even become infected. When the child scratches the itching anal area, the eggs can get under the child’s fingernails and be transferred to other children, family members, and items in the house.


  • Intense itching around the anus  
  • Difficulty sleeping due to the itching that occurs during the night, when the adult worms migrate out through the anus to lay their eggs  
  • Irritability due to the itching and interrupted sleep at night  
  • Vaginal irritation or discomfort in young girls (if an adult worm enters the vagina rather than the anus)  
  • Irritated or infected skin around the anus from constant scratching  
  • Loss of appetite and weight (uncommon but can occur in severe infections)

Signs and tests
Pinworms can be spotted in the anal area, especially at night when the worms lay their eggs there. Your doctor may have you do a tape test. A piece of cellophane tape is pressed against the skin around the anus, and removed. This should be done in the morning before bathing or using the toilet, because bathing and wiping may inadvertently remove any eggs. The doctor will stick the tape to a slide and look for eggs using a microscope.


The main treatment is anti-parasitic medication, available over-the-counter and by prescription. More than one household member is likely to be infected, so the entire household is often treated. Treatment is often repeated after 2 weeks.

To control egg infestation, wash hands before meals and after using the toilet, keep fingernails short and clean, wash all bed linen twice weekly, and clean toilet seats daily.

Avoid scratching the infected area around the anus, because this contaminates the fingers and everything else that is subsequently touched. Keep hands and fingers away from the nose and mouth unless they are freshly washed. Carry out these measures while family members are treated with medication.

Expectations (prognosis)
Pinworm infection is fully treatable.


  • salpingitis  
  • vaginitis  
  • reinfestation

Calling your health care provider
Call for an appointment if you or your child has symptoms of pinworm infection or if you have seen pinworms on your child.

Wash hands after using the bathroom and before preparing food. Wash bedding and underclothing frequently, especially those of any affected family members.

Johns Hopkins patient information

Last revised: December 7, 2012
by Sharon M. Smith, M.D.

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