What are Threadworms?
Threadworms, also known as pinworms, are tiny white parasitic worms that live in the intestines and lay eggs around the anus. They’re one of the most common worm infections in the UK, particularly affecting children under 10 years old, though anyone can get them.
Around 1cm long, about the size of a staple, these worms look like small white threads, which is how they got their name. While harmless, they can be uncomfortable and irritating, especially at night when the female worms lay their eggs.
See what threadworms look like
How do Threadworms Spread?
Threadworms spread when tiny eggs transfer from person to person, usually through hand-to-mouth contact. The eggs are invisible to the naked eye, making them easy to spread without realising.
Female threadworms lay eggs around the anus at night, causing itching. When someone scratches, eggs get under their fingernails and transfer to everything they touch – bedding, towels, toys, food, or other surfaces. The eggs survive for up to two weeks outside the body.
When someone touches these contaminated surfaces and puts their hands in their mouth, they swallow the eggs. The eggs hatch in the large intestine, and the cycle continues.
You’re more at risk if you:
- Live with or care for young children
- Are in close contact with someone who has threadworms
- Share bedding, towels, or clothing with an infected person
- Don’t wash your hands regularly, especially before eating
- Bite your nails or suck your thumb
- Live in crowded conditions like schools, nurseries, or care homes
Symptoms of Threadworms
The most common symptom is an itchy bottom, particularly at night or early morning when the female worms lay their eggs. However, some people have no symptoms at all.
Other signs include:
- Irritability and restlessness, especially in children
- Difficulty sleeping
- Small white threads in stools or around the anus
- Red, irritated skin around the bottom from scratching
- In girls, irritation or itching around the vagina
- Stomach pain or discomfort (less common)
- Loss of appetite (less common)
- Bedwetting in previously dry children
The worms look like small pieces of white thread, about 2-13mm long, and may be moving. You might spot them in stools or around the bottom when wiping.
Treatment for Threadworms
Threadworm infections are straightforward to treat with medication. The most important thing is that everyone in your household gets treated at the same time, even if they don’t have symptoms. This prevents the infection from spreading back and forth between family members.
Mebendazole (Ovex)
Mebendazole is the most commonly used treatment for threadworms, available as Ovex tablets and Ovex suspension. It works by stopping the worms from absorbing the sugars they need to survive, killing them so they pass out naturally in your stools.
Ovex Tablets are suitable for adults and children over 2 years old. Take a single tablet, then another two weeks later to catch any worms that hatch from eggs after the first dose.
Ovex Suspension is an orange-flavoured liquid ideal for children or anyone who has difficulty swallowing tablets. It contains the same active ingredient and works identically to the tablets.
The itching usually improves within a few days, though it can take up to a week to disappear completely. The dead worms pass in your stools over the next few days, though you might not notice them.
For children under 2 years old, or if you’re pregnant or breastfeeding, speak to your GP or pharmacist before taking any medication.
Hygiene Measures to Prevent Reinfection
Medication alone isn’t enough to get rid of threadworms completely. You need to follow strict hygiene measures for at least six weeks to break the cycle of reinfection. This might seem like a long time, but it’s necessary because threadworm eggs can survive on surfaces for up to two weeks.
Here’s what you should do:
Daily Habits
- Wash your hands thoroughly with soap and water, especially after using the toilet, before eating, and before preparing food
- Keep fingernails short and clean – scrub under them with a nail brush
- Avoid nail biting and thumb sucking
- Shower or bath every morning to remove eggs laid overnight
- Change and wash underwear, nightwear, and bed linen daily
Around the Home
- Vacuum and damp-dust your home regularly, paying attention to bedrooms
- Wash bedding, towels, and soft toys on a hot wash (at least 60°C)
- Don’t shake bedding or clothes before washing, as this spreads eggs into the air
- Disinfect door handles, toilet seats, and other frequently touched surfaces
- Keep toothbrushes in a closed cupboard and rinse before use
For Children
- Make sure they wear close-fitting underwear at night to prevent scratching
- Wearing cotton gloves at night can stop them from scratching in their sleep
- Encourage them to wash their hands properly (always supervise young children)
- Keep their bedroom as dust-free as possible
These measures might feel overwhelming, but they’re essential for preventing reinfection. The whole family should follow them, not just the person with symptoms.