Threadworms are the most common worm infection in the UK, and most of the households dealing with them include young children. If a note has come home from nursery or school, or you have heard the word from a pharmacist, this guide explains what threadworms are, how they spread, and what the NHS advises families to do.
The short version is reassuring. Threadworms are very common, they are not a sign of a dirty home, and for most families the whole thing is sorted through a pharmacy. This guide is written for parents, and it is for information only. Nothing on this page can tell you whether your child has threadworms. A pharmacist, your GP or your health visitor can, and they are the right people to ask.
What are threadworms?
Threadworms, also called pinworms, are small white worms with the scientific name Enterobius vermicularis. They live in the lower part of the gut, and the female worms lay their eggs on the skin around the bottom, usually at night.
NICE's clinical knowledge summary for GPs describes threadworms as the most common worm infection in the UK, seen mainly in children. That is clinical guidance rather than a recent count, a distinction that matters in the next section. For most healthy children a threadworm infection is an irritation rather than a danger, and it is treatable.
Threadworms are one of several parasites that turn up in UK guts, though as a worm they behave very differently from the waterborne infections that cause stomach upsets. Our guide to gut parasites covers the wider picture, including the infections linked to water, food and travel.
How common are threadworms in UK children?
The honest answer is that nobody has measured this properly in the UK for years. Recent prevalence studies come from countries such as Thailand, China and Korea, not from Britain. So the UK picture in this guide comes from NHS and NICE guidance, which reflects what GPs and pharmacists see, and we label it as guidance wherever it appears rather than presenting it as study data.
The research from comparable countries suggests the guidance is right to call threadworms common. According to PubMed records, a 2019 clinical review from Germany estimated that around 20 per cent of nursery and primary-school children in Europe are affected, with more than a billion people infected worldwide (Wendt et al., 2019). A 2025 review of the past decade's research put the worldwide figure at roughly 30 per cent of children affected at some point, with the highest rates between the ages of 5 and 14 (Leung et al., 2025).
Northern Europe is no exception. When 364 Norwegian children were tested with the standard tape test, between 17.5 and 37 per cent tested positive depending on the group (Boas et al., 2013). Norway is a wealthy country with good sanitation, much like the UK. Threadworms are simply very good at moving between young children, whatever the state of the bathroom at home.
How do threadworms spread?
Threadworms spread when the eggs are swallowed. The eggs are laid on the skin around the bottom, transfer onto hands and under fingernails, and from there onto bedding, clothes, towels, toys and surfaces, where research shows they can survive for around two to three weeks (Leung et al., 2025).
This is why the infection circulates so efficiently in nurseries, schools and family homes. Young children put their hands in their mouths constantly, and the itching the worms cause encourages scratching, which loads the eggs back onto fingers and starts the cycle again. The same reviews note that adults in a household can be infected too, although rates outside childhood are much lower (Wendt et al., 2019).
One useful thing to know: when threadworms come back after treatment, research suggests it is usually reinfection from eggs still in the environment, or from an untreated household member, rather than the treatment failing (Wendt et al., 2019). That is why the NHS advice below treats the whole household and pairs medicine with hygiene measures.
What do parents typically notice?
What follows describes what studies have observed across large groups of children. It is not a checklist for your child, and it cannot be, because the picture varies too much from child to child for a list to settle anything.
In the research, the most commonly reported feature of threadworm infection is itching around the bottom, typically worse at night when the worms lay their eggs. Disturbed sleep and irritability follow from the itching in some children. At the same time, the reviews estimate that 30 to 40 per cent of children carrying threadworms have no symptoms at all (Leung et al., 2025).
Those two facts together explain why this guide will not help you decide whether your child has threadworms. An itchy bottom and broken sleep have many possible causes, and a substantial share of infected children show nothing. If threadworms are on your mind, the practical step is a conversation with a pharmacist, your GP or your health visitor, who deal with this constantly and will not be remotely surprised by the question.
How are threadworms confirmed?
Usually they do not need a laboratory at all. NHS guidance describes threadworms as something that is generally recognised rather than formally tested for, and a pharmacist can advise on the strength of a conversation.
Where confirmation is genuinely needed, a GP can arrange what is called a tape test: a piece of clear adhesive tape is applied to the skin around the bottom first thing in the morning and examined under a microscope for eggs. One tape test picks up only around half of infections, and research shows that tests on three separate mornings lift that to roughly 90 per cent (Leung et al., 2025), so a single clear result does not close the question.
Why a stool test is the wrong test for threadworms
Threadworm eggs are laid on the skin outside the body, not released into poo, so stool samples usually contain nothing to find. The 2025 review states plainly that stool examination is not recommended for diagnosing threadworms (Leung et al., 2025). The size of the gap is striking: a 2025 analysis pooling 56 studies and more than 52,000 people found the tape method detected infections at nearly 40 times the rate of stool examination, 12.9 per cent against 0.33 per cent (Jongthawin et al., 2025).
That includes home stool tests, and it includes ours. Feel Gut sells stool-based testing kits, and they are the wrong tool for this job. No stool test, from us or anyone else, is a sensible way to look for threadworms. The right route is a pharmacist for advice and treatment, or a GP if confirmation is needed.
How are threadworms treated in the UK?
The UK pathway is pharmacy first, and it comes from NHS guidance rather than from us. Per the NHS threadworms guidance, treatment for most people is available from a pharmacy without a prescription, and everyone in the household is normally treated at the same time, even those with no symptoms, because so many infections are silent and the eggs pass around a household easily.
The same NHS guidance is specific about who should not go straight to the pharmacy shelf: for a child under 2, and in pregnancy or breastfeeding, speak to a GP first, because the standard medicine is not routinely used in those groups. Treatment decisions for your household sit with the pharmacist or GP, not with this page, and the medicine is usually combined with the hygiene measures below because medicine alone does not deal with eggs already in the home.
Recurrences are common and are usually reinfection rather than failed treatment, as covered above. If threadworms keep returning despite treatment and hygiene measures, that is a GP conversation, and clinical reviews describe longer repeated courses being used for stubborn recurrences under medical supervision (Wendt et al., 2019).
What hygiene measures does the NHS advise?
These are the NHS-advised measures, and they exist because of how the eggs spread: from skin to hands to fabric and surfaces, and back to mouths. Per NHS guidance, for around two weeks alongside treatment:
- Wash hands and scrub under fingernails, particularly before eating and after using the toilet
- Keep fingernails short, and discourage nail biting and thumb sucking
- A bath or shower each morning, to wash away eggs laid overnight
- Change and wash underwear, nightwear, and towels regularly, and wash bed linen
- Avoid shaking bedding and clothes, which spreads eggs into the air and around the room
- Rinse toothbrushes before use and keep them in a closed cupboard
Hygiene is also the population-level success story here. The pooled Thai analysis found prevalence fell substantially over two decades as hygiene interventions took hold (Jongthawin et al., 2025). The measures look mundane, and they are the reason threadworms are less common than they used to be.
When should you seek advice the same day?
Threadworms themselves are rarely serious. But some signs in a child always warrant same-day advice, whatever the suspected cause, and they are worth knowing in their own right. Contact your GP surgery or NHS 111 the same day if a child has blood in their poo, persistent vomiting, is refusing feeds, is unusually drowsy or difficult to wake, has fewer wet nappies than usual, or is not gaining weight as expected.
None of those is a typical feature of threadworms. They are the general signs that a child needs prompt assessment, and no home measure, and certainly no test, should ever delay that call.
Beyond the same-day list, see a GP first for a child under 2, in pregnancy or when breastfeeding, and whenever symptoms continue or keep returning after pharmacy treatment.
This guide is for information only and does not replace medical advice. For anything concerning your child's health, speak to your GP, pharmacist or health visitor.
Sources
- Leung AKC, et al. (2025). Pinworm (Enterobius vermicularis) Infestation: An Updated Review. Current Pediatric Reviews. https://pubmed.ncbi.nlm.nih.gov/38288810/
- Wendt S, et al. (2019). The Diagnosis and Treatment of Pinworm Infection. Deutsches Arzteblatt International. https://pubmed.ncbi.nlm.nih.gov/31064642/
- Boas H, et al. (2013). Enterobius vermicularis and allergic conditions in Norwegian children. Epidemiology and Infection. https://pubmed.ncbi.nlm.nih.gov/24331127/
- Jongthawin J, et al. (2025). Prevalence and Epidemiological Patterns of Enterobius vermicularis Infection in Thailand: A Systematic Review and Meta-Analysis. Medical Sciences (Basel). https://pubmed.ncbi.nlm.nih.gov/41133489/
This guide also refers to UK clinical guidance rather than studies for the UK pathway and hygiene advice: the NHS guidance on threadworms and the NICE clinical knowledge summary on threadworm. These are guidance documents, reflecting clinical practice, not prevalence research.
