This fact sheet is available in the following languages: Chinese (simplified),  Chinese (traditional) and English.

There are many different types of intestinal worms, but the most common is threadworm (also called pinworm). Threadworm is a type of roundworm that is commonly found in preschool and school-aged children, however the whole family can become infected.

Threadworm causes a very itchy bottom, which is usually worse at night. If your child is infected with threadworm, it is not usually serious and can be treated easily with medication.

Signs and symptoms of threadworm

If your child has threadworm, they may:

• have an itchy bottom, which may become red and inflamed from scratching
• be irritable and generally ‘out of sorts’
• not sleep very well
• have a reduced appetite.

In girls, there may also be redness and itching around the vaginal area. (Threadworms may cause or worsen vulvovaginitis in girls. See our fact sheet Vulvovaginitis.)

You may be able to see threadworm if you examine your child at night. Take a torch, separate your child’s buttocks and look carefully around the anus (and the opening to the vagina in girls). You might see tiny white threads that may be moving.

How is threadworm spread?

Threadworm gets its name because the worms look like white threads, which are about 1 cm long. The worms live in the lower intestine, but they come out of the anus over night to lay their eggs in the area between the buttocks, which causes your child’s bottom to feel very itchy. It is estimated that one female threadworm can lay up to 16,000 eggs.

Threadworm is spread when children scratch their bottom, causing the eggs to collect under the fingernails. The child then carries the worm eggs back to their mouth with their hands. The eggs can also be spread indirectly, in food, dust, or other items. The eggs can survive up to two weeks outside the body.

Once your child swallows threadworm eggs, the eggs hatch in your child’s small intestine and the worms travel down to their anus.

You cannot catch threadworm from animals.

Care at home

You can talk to a pharmacist about over-the-counter treatment options. Drugs such as pyrantel (Combantrin) or mebendazole (Banworm) are very safe and often recommended. Follow the instructions on the packet, bearing in mind special precautions may be given for children under two years of age and for pregnant women.

• Treat all the family members at the same time, even if they aren’t showing any symptoms. Adults can also get threadworm.
• If possible, your child should have a shower on the night they have the medicine, and again the next morning to remove the eggs laid during the night.

Unfortunately, repeat threadworm infection is very common. To help reduce this and to prevent the threadworms from spreading to others, you can take the following precautions:

• Despite the itching, encourage your child not to scratch their bottom. If they must scratch, make sure it is over their underpants and not directly on their skin.
• Keep your child’s fingernails clean and trimmed. Try to stop your child from biting their nails or sucking their thumb.
• Have your child wash their hands and under their nails thoroughly after going to the toilet.
• Wash your child’s bedding, towels and toys in hot water.
• Vacuum your floor often to remove any eggs. 
• Clean surfaces in your house that your children may touch, in particular door handles.
• Discourage your child from eating food that has fallen on the floor.

When to see a doctor

If you have tried a threadworm treatment for your child and their symptoms have not improved, take them to your GP. The doctor will examine your child and may want to do blood or faeces (poo) tests. Also take your child to the GP if:

• your child passes a large worm
• they have abdominal pain, nausea, vomiting or low energy levels.

Key points to remember

• Threadworm is common in preschool and school-aged children.
• Threadworm causes very annoying itching in the area between a child’s buttocks.
• It’s easy to treat threadworm with the right medication.
• There are precautions to prevent threadworm spreading and reinfecting.

For more information

• Kids Health Info fact sheet: Vulvovaginitis
• Kids Health Info fact sheet: Stopping the spread of germs
  
• Raising Children Network: Worms
• See your GP, Maternal and Child Health Nurse or pharmacist.

Developed by The Royal Children's Hospital General Medicine and Infectious Diseases departments. We acknowledge the input of RCH consumers and carers.

Reviewed September 2020.

Kids Health Info is supported by The Royal Children’s Hospital Foundation. To donate, visit www.rchfoundation.org.au.