Pinworm infection

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Pinworm infection


​Pinworm is a human parasitic worm and occurs worldwide. Pinworm infection is not dangerous but it may cause an epidemic in families, nurseries or schools.  Pinworm infection can be treated with over-the-counter medication.

Pinworms are white, approximately one centimetre long parasitic worms. You become infected with pinworms by unintentionally ingesting or inhaling pinworm eggs.  The infection is spread via hands, clothes, bed linen and toys.  The eggs are too small to be visible to the naked eye, and they may remain contagious on surfaces for several days. Pinworm infections have nothing to do with lack of hygiene or care.


​The period between swallowing eggs and the appearance of symptoms is approximately six weeks. The worms hatch from the eggs in the small intestine. From the small intestine, the fertilised pinworm moves on to the large intestine and finally settles near the appendix where it reproduces. A typical symptom is itching in the anus, vaginal and perineal area during the night. However, most of the carriers may show no symptoms at all. The symptoms are caused by the movements of the worms and the irritation caused in the mucous membrane protecting the eggs. As a result of scratching the anal area, pinworm eggs spread in the hands to the environment and a pinworm infection recurs. One pinworm egg is enough for a new infection.

A high level of hand hygiene is essential because a carrier can easily recontaminate themselves again.​​


​Pinworms are treated with a medicine called Pyrvin, which is available in pharmacies without a prescription.  Pharmacy staff will help you select the right product, if necessary. Although a single dose is effective, the treatment is repeated after two weeks to stop becoming infected again.  Especially in families with children, the whole family should be treated at the same time to prevent recontamination, because some family members may be carriers without knowing it.

In addition to medical treatment, bedlinen, towels, and underwear should also be washed on the day following the administration of the medication. Normal housekeeping routines are sufficient for cleaning the bathrooms and other areas. Inform your children’s schools or nurseries about a confirmed pinworm infection to avoid a wider epidemic, however, no non-attendance is required.  

When should you seek medical advice?

​You should seek medical advice, if

  • the symptoms persist despite self-care.
  • the symptoms get worse.
  • you experience abdominal pain.​​

More information

The producers of the instruction

​​​​​Emergency care professionals have produced the instruction in collaboration with Terveyskirjasto.​


Updated  1.5.2021