Threadworms are the most common type of intestinal worm, which can affect people of all ages but are most commonly seen in young children. Threadworms are small, thin, white worms that lay thousands of eggs around the anus causing those infected to experience intense itching around the anus, especially during the night. The worms are spread by swallowing the eggs, from an infected person directly to another person or via clothes or other objects. Treating the worms is quick and easy with most people seeing noticeable improvements in just 3 days.
Don't wait any longer to get the medical help you need. View our recommended treatments and select your preferred treatment and quantity from a list of options for you.
Threadworms, also known as pinworms, are the most common form of worm infection in the UK and are particularly common amongst young children under the age of 10. Threadworm infections are generally caused by poor hygiene – not washing your hands after using the toilet (or touching/scratching the anal area) results in threadworm eggs being stuck under the fingernails and being passed on to anything you touch.
These tiny parasitic worms infect and hatch eggs in the large intestine of humans. They resemble a tiny piece of white thread, approximately one centimetre in length and can be visible around the anus or vaginal area and also in the stools.
Threadworms are not harmful, however, they can be uncomfortable and also embarrassing for the sufferer due to the nature of the area they infect. They should be treated as soon as possible to relieve symptoms and prevent spread.
Threadworms do not always cause symptoms but the most common is itchiness around the bottom (or vaginal area in girls), especially at night. This can lead to interrupted sleep due to discomfort and irritability.
More severe threadworm infections can cause skin infections around the anus from where bacteria have been able to enter the raw, scratched skin. Loss of appetite and subsequently weight loss are also symptoms attributed to severe or persistent threadworm infections. In extreme and rare cases it has been known for threadworms to spread beyond the large intestine and nest in other places, such as the urinary tract, the liver and for women, in the vagina. If any of these symptoms are present you should see your GP for treatment.
Usually threadworm, or pinworm, can be diagnosed and treated at home without the need to see a doctor.
Diagnosis of a threadworm infection can normally be made with a combination of the symptoms detailed above and the presence of threadworms in the stools. Usually a diagnosis from a doctor is not necessary unless the sufferer is a child under 2 years old or is a woman who is pregnant or breastfeeding.
Treatment for threadworms will need to include everyone in your household. This is because the risk of the infection spreading is very high. This will also need to include people who aren’t currently presenting with any symptoms. The majority of cases of threadworm treatment will involve a single dose of Mebendazole, which is the drug contained in the branded medicine, Ovex. Mebendazole is 90-100% effective at killing the threadworms and normally does this within a couple of days, after which your symptoms should subside.
Ovex does not kill the eggs, which is why strict hygiene measures (outlined below) should be followed for six weeks after treatment. This will ensure the threadworm’s eggs aren’t spread and cause reinfection. A follow-up dose of Ovex can be taken after two weeks if required.
The threadworm treatment, Ovex, is available as a chewable tablet or banana-flavoured suspension that is suitable for children aged 2 years and over. Children under 2 years that are suffering with threadworm require attention from their GP. Ovex threadworm treatment is also not suitable for those who are pregnant or breastfeeding.
Threadworm treatment should always include preventative and hygiene measures for at least 6 weeks as detailed in ‘Prevention’ below.
It’s not always possible to prevent threadworm infection but by following common sense hygiene practice the risk of infection can be significantly reduced, such as:
No, threadworms only infect humans and are not spread in animal faeces. Their eggs however, can stick to animal fur if touched by someone who is infected. This can then be spread to be other peoples hands from touching or stroking the pet.
Yes, although it is more common in children, people of any age can catch threadworms.
If you suspect threadworms and you are pregnant or breastfeeding, or if you think your child, who is under two years of age, has threadworms then it is necessary to consult a GP prior to treatment. The treatment in these cases can differ from what is recommended for other people.
No, there is no need to keep children off school if they have a threadworm infection. It is likely that other children in the school already have threadworm so the best approach is to inform the teachers and ensure the school is enforcing a good hygiene approach with all children.
Not treating threadworms is unlikely to lead to any serious consequences, although there are more severe symptoms as detailed above. The symptoms of threadworms such as anal itching, and the subsequent sleep disturbance, can often be difficult to live with and will persist if the infection is not treated.
Yes, as threadworms are very easily spread the whole family should be treated at once to help prevent the risk of re-infection.
No, threadworms are very common in children and are easily treatable.
Reviewed by
Dan is an experienced pharmacist having spent time working in both primary and secondary care. He currently supports our clinical team by providing robust clinical governance review of our internal processes and information.
Or browse all treatments or conditions
