General information

Pinworms are white, approximately one centimetre long parasitic worms. Pinworms may cause an epidemic in families, nurseries, school or care facilities. Pinworms have nothing to do with poor hygiene or lack of care.

The eggs of the pinworm travel via hands, clothes, bed linen and toys to the mouth and the gastrointestinal tract. The eggs are too small to be visible to the naked eye, and they may remain contagious on surfaces for up to 1–2 weeks.

The worms hatch from the eggs in the small intestine. From the small intestine, the fertilised pinworm moves on and settles near the appendix where it reproduces. Eventually, the pinworm moves close to the rectum to produce eggs. From the anus-area, the eggs may spread via hands to the environment. The period between swallowing eggs and the appearance of symptoms is approximately six weeks.

A typical symptom, especially with children, is itching in the anus, vaginal and perineal area during the night. Some patients also have abdominal pain. Some of the carriers, especially adults, 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.

The symptoms and scratching caused by this parasite may cause bedwetting, poor quality of sleep, irritability, bacterial infections and even loss of appetite.

While pinworms are very unpleasant, they are not dangerous. A high level of hand hygiene is essential because a carrier can easily recontaminate themselves as eggs get caught in the hands and under the nails when scratching the rectal area.


Pinworms are treated with a medicine called Pyrvin, which is available in pharmacies without a prescription. Follow the instructions on the package carefully and you can always ask for further advice from pharmacy staff. The treatment is repeated after two weeks. 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.

Sheets (bedlinen), towels, and clothes should also be washed on the same day as the medication is taken and all bedding should be vacuumed and dusted or aired outside in freezing weather, because eggs may be nesting in textiles. Inform your children’s schools or nurseries to avoid a wider epidemic. Make sure that small children regularly wash their hands and keep their nails short and scrub under their nails to stop the circulation of pinworm eggs.

When should you seek medical advice?

If the symptoms persist despite home treatment or the symptoms get worse (particularly abdominal pain), it is best to seek medical advice to rule out any other cause.

This Self-care instruction has been produced in collaboration with Duodecim Terveyskirjasto

Previous page Next page

Updated  8.6.2020