Executive summary
- Classic presentation: intense perianal itching that is worse at night, often in children, with disturbed sleep and spread between household members.
- Management is not just a prescription: reinfection is common, so treatment often needs to cover the index case and household contacts plus a structured hygiene plan.
- If the diagnosis is uncertain, use the history well and consider tape-test style confirmation rather than overcomplicating the work-up.
Diagnosis and practical assessment
- Most diagnoses are clinical: perianal itch, especially nocturnal, is the key clue.
- Ask about sleep disruption, household spread, irritability, and scratching-related secondary skin irritation.
- If uncertain, a morning adhesive tape sample before washing can help detect eggs.
Treatment and prevention of reinfection
- Mebendazole: 100 mg as a single dose is the standard option for adults and for children from 6 months of age, with a second dose after 2 weeks if reinfection occurs or persists.
- If the diagnosis is certain, NICE CKS recommends re-treatment of the person and household contacts with mebendazole unless contraindicated.
- Hygiene is essential: when mebendazole is used, continue strict hygiene measures for 2 weeks; if hygiene measures alone are used, continue them for 6 weeks.
- Children under 6 months are generally managed with hygiene measures alone for 6 weeks.
Frequently asked questions
Why does threadworm keep recurring?
Because reinfection is common. Treating only one person while ignoring household spread and hygiene almost guarantees the problem comes back.
Do I need to treat the whole household?
If the diagnosis is certain, NICE CKS supports treatment of the affected person and household contacts, unless treatment is contraindicated.
What is the biggest management mistake?
Stopping at the prescription. Hygiene measures and bedding/handwashing advice are a core part of effective management, not an optional extra.
Transparency
This page is an educational, clinician-written summary of publicly available NICE guidance intended for trained healthcare professionals. It uses original wording (not copied text) and should be used alongside the full NICE source, local pathways, and clinical judgement. Doses provided are for general reference; always check the BNF/SPC.