Threadworms
Tiny white worms that cause an itchy bottom at night, mostly in children, and then quietly move in with everyone else. Harmless, very common and easy to treat, as long as you repeat the dose.
Typical signs: an itchy bottom, worst at night, redness from scratching, poor sleep and grumpiness. Girls may get an itchy vulva. You may see white threads about 1 cm long in poo, or around the bottom at night with a torch.
How they spread: females lay eggs around the bottom at night. Scratching puts eggs under nails and onto food, toys and surfaces, where they survive up to 2 weeks. Swallowed eggs hatch in the gut. You can’t catch them from pets.
How common: the most common gut worm in Australia, and common worldwide in preschool and school-aged children.
The threadworm ladder
Medicine kills the worms, not the eggs. That’s why everyone is treated at once, and the dose is repeated.
- Step 1 · PharmacyMebendazole or pyrantel for the whole householdOne dose for everyone aged 2 and over, at the same time, even without symptoms.
- Works
- Effective and very safe for children over 2
- Cost
- About $10–20 a pack
- How long
- One dose now, repeated 1–2 weeks later
- Watch for
- Under 2s, pregnancy and breastfeeding: ask a doctor or pharmacist first. Tummy ache, wind or diarrhoea.
Everyone gets a dose. Yes, even the one who swears they’re fine.
- Step 2 · Self-careHygiene for a couple of weeksShort nails, handwashing after the toilet and before eating, a morning shower, underpants at night, hot-wash bedding and towels.
- Works
- Breaks the egg cycle, since eggs survive up to 2 weeks
- Cost
- Free
- How long
- At least 2 weeks after treatment
- Watch for
- Nail-biting and thumb-sucking help eggs travel.
Boring, unglamorous and essential.
- Step 3 · PharmacySoothing cream for the itchA gentle barrier or soothing cream at bedtime.
- Works
- Comfort only; treating the worms is the real itch fix
- Cost
- About $8–15
- How long
- A few days
- Watch for
- Wash hands well after applying.
Treat the cause, soothe the symptom.
- Step 4 · GPDoctor reviewIf it keeps coming back, or for children under 2 or during pregnancy.
- Works
- A third dose may be considered if infections keep recurring
- Cost
- GP fees; often bulk-billed for children
- How long
- Varies
- Watch for
- A large worm in poo is a different worm and needs a check.
Rarely needed, but here if you are.
Save your money
Popular, heavily marketed or often asked about, but the evidence is weak or says no.
- Deworming the dog or cat for threadwormsPeople can’t catch threadworms from pets. Ask the vet about pet worms separately.
- Treating only the itchy childOthers are often infected without symptoms. Treat everyone, or play ping-pong for months.
- Keeping kids home for daysTreat them and send them back. There’s no need to miss school or childcare.
What you can do
- Treat everyone in the house on the same day, then repeat in 1–2 weeks.
- Keep nails short and clean, and wash hands before every meal.
- Shower each morning and change underpants daily.
- Hot-wash bedding, towels and soft toys daily for a few days after treatment.
See your GP if
- It hasn’t cleared after pharmacy treatment and several weeks
- A large worm is seen in poo or around the bottom
- Your child has tummy pain, nausea, vomiting or low energy
- The person is under 2, pregnant or breastfeeding
Pregnant? Speak to a doctor or pharmacist before taking worm medicine. Hygiene measures alone may be suggested first, particularly early in pregnancy.
Common questions
Did my child catch threadworms from our dog?
No. People cannot catch threadworms from pets, so there is no need to deworm the pets for this.
Does the whole family need treatment?
Yes. Everyone aged 2 and over should be treated at the same time, even without symptoms, because others are often infected.
Why do we need a second dose?
The medicine kills adult worms but not the eggs. A repeat dose 1 to 2 weeks later kills worms that hatched from eggs swallowed after the first dose.
Can my child go to school with threadworms?
Yes. Treat them before they return; there is no need to keep them home.
Helpful resources
- Royal Children’s Hospital: ThreadwormsPractical parent fact sheet with myths answered. Free, Australia.
- NHS: MebendazoleWho can take it and how. Free, UK.
Evidence and more information
maladywise.com/threadworms/