Threadworms in children: a case-based approach

The case: night-time itching

A 6-year-old has been scratching around the bottom, mostly at night, and is sleeping poorly and irritable. On checking, a parent sees tiny white threads, like short pieces of cotton, in the folds around the anus or in the child's pants. This is the classic picture of threadworms, also called pinworms. They are small parasitic worms that live in the large intestine. At night the female worms crawl out to lay eggs on the surrounding skin, which triggers intense itching. Scratching then transfers microscopic eggs onto fingers and under nails, from where they spread. Seeing the worms or their effect is often enough to recognise the problem without any test.

How threadworms spread

Threadworms spread when eggs are swallowed. After scratching an itchy bottom, a child gets eggs on their hands; these are then transferred to the mouth directly, or onto food, toys, bedding, towels, and surfaces that others touch. The eggs can survive for around two weeks outside the body and are too small to see. Once swallowed, they hatch and grow in the gut, and the cycle repeats. Because spread is so easy, several members of a household often carry threadworms even if only one has symptoms. This is why the infection is so common in families and at school, and why treating and cleaning need to cover everyone rather than just the child who is itching.

The pharmacist-first pathway

Threadworms can usually be managed without seeing a GP. A community pharmacist is the ideal first port of call: they can confirm the likely diagnosis from the description, recommend a suitable over-the-counter worming treatment, and advise on hygiene. Because the worms spread so readily, the standard approach is to treat everyone in the household at the same time, even those without symptoms, unless advised otherwise. Treatment is generally not recommended during pregnancy or for children under a certain age, in which case strict hygiene measures alone are used for a period; the pharmacist will guide this. A GP's advice is worth seeking if symptoms persist after treatment and hygiene, or if you are unsure whether it is threadworms.

Hygiene: breaking the cycle

Medicine kills the worms but not their eggs, so hygiene is essential to stop reinfection while treatment works. Helpful measures for about two weeks include washing hands and scrubbing under the nails, especially before eating and after using the toilet; keeping nails short and discouraging nail-biting and scratching; and bathing or showering first thing in the morning to remove eggs laid overnight. Wash bedding, towels, sleepwear, and soft toys on a hot wash, and avoid shaking them, which can scatter eggs. Damp-dust and vacuum surfaces, and keep toothbrushes covered. Encouraging children to wear close-fitting underwear at night can reduce scratching. Doing these together with treatment gives the best chance of clearing threadworms from the whole household.

When to seek more help

Threadworms themselves are not dangerous, but a few situations warrant a clinician's advice. See a pharmacist or GP if symptoms continue despite correct treatment and thorough hygiene, if worms keep coming back, or if you are unsure of the diagnosis. Seek tailored advice for children under two, and for anyone who is pregnant or breastfeeding, as the usual medicine may not be suitable and hygiene measures may be relied on instead. Very rarely, girls may develop itching or discomfort around the genital area if worms migrate there, which is worth mentioning to a clinician. Persistent tummy pain, weight loss, or feeling generally unwell are not typical of threadworms and should prompt a medical review to look for another cause.