Treating threadworms 

To treat threadworms successfully, all household members must be treated, even if they don't have any symptoms. This is because the risk of the infection spreading is very high.

The aim of treatment is to get rid of the threadworms and prevent reinfection. This will usually involve a combination of medication to kill the worms and strict hygiene measures to stop the spread of the eggs.

The main medication used to treat threadworms is available from your local pharmacy without a prescription. However, it's important to follow the manufacturer's instructions as it isn't suitable for everyone.

You only need to see your GP if you think:

  • you have threadworms and you're pregnant or breastfeeding
  • your child has threadworms and they're under two years old

This is because the recommended treatment in these circumstances usually isn't the same as that recommended for most other people.


Mebendazole is the main medication used to treat threadworm infections. It can be bought over the counter from your local pharmacy or prescribed by your GP. It's available as a chewable tablet or a liquid.

Mebendazole works by preventing the threadworms absorbing sugar, which means they should die within a few days.

This medication is 90-100% effective at killing the threadworms, but it doesn't kill the eggs. This is why the hygiene measures outlined below should also be followed for six weeks.

Visit your GP if the infection continues two weeks after treatment. They may recommend a second dose of medication.

In rare cases, mebendazole can cause abdominal pain or diarrhoea, particularly if the threadworm infection is severe.

Hygiene measures

Strict hygiene measures can help clear up a threadworm infection and reduce the likelihood of reinfection.

The lifespan of threadworms is approximately six weeks, so it's important that hygiene measures are followed for at least this length of time. Everyone in the household must follow the advice outlined below.

  • wash all night clothes, bed linen, towels and soft toys when you're first diagnosed – this can be done at normal temperatures, but make sure the washing is well rinsed
  • thoroughly vacuum and dust the whole house, paying particular attention to the bedrooms – this should be repeated regularly
  • carefully clean the bathroom and kitchen by damp-dusting surfaces and washing the cloth frequently in hot water – this should be repeated regularly
  • avoid shaking any material that may be contaminated with eggs, such as clothing or bed sheets – this will prevent eggs being transferred to other surfaces
  • don't eat food in the bedroom – you may end up swallowing eggs that have been shaken off the bedclothes
  • keep your fingernails short – encourage other members of your household to do the same
  • discourage nail-biting and sucking fingers – in particular, make sure children don't suck their thumb
  • wash your hands frequently and scrub under your fingernails – it's particularly important to do this before eating, after going to the toilet, and before and after changing your baby's nappy
  • wear close-fitting underwear at night and change your underwear every morning
  • bathe or shower regularly – it's particularly important to bathe or shower first thing in the morning: make sure you clean around your anus and vagina to remove any eggs
  • ensure everyone in your household has their own face flannel and towel – don't share towels
  • keep toothbrushes in a closed cupboard and rinse them thoroughly before use

Children can easily pick up another threadworm infection from friends or at school, so maintaining good hygiene may help prevent reinfection.

Pregnant or breastfeeding women

Medication isn't usually recommended for pregnant or breastfeeding women. Instead, you should follow the hygiene measures above.

See your GP if you're more than three months pregnant, or if you're breastfeeding and you continue to experience problems after only taking hygiene measures. In certain circumstances, your GP may consider prescribing medication.

Children under two years old

Make sure you wash your baby's bottom gently but thoroughly every time you change their nappy. Also wash your hands thoroughly before and after changing their nappy.

Mebendazole isn't licensed for use in children under two years of age, but GPs may decide to prescribe it off-label for children over six months.

If medication isn't used, the hygiene measures outlined above are recommended instead.

Read more about unlicensed medicines.

Should work or school be avoided?

It isn't necessary to stay off work or school if you or your child has a threadworm infection.

However, you should inform staff at your child's school or nursery so they can take steps to prevent the spread of infection, such as cleaning toys and equipment and encouraging children to wash their hands regularly.

Page last reviewed: 24/08/2015

Next review due: 24/08/2017