Pinworm infection is a common intestinal infection caused by the small roundworm Enterobius vermicularis. It is especially common in children and can spread easily among people living in the same household.
Symptoms
The most typical symptom is intense itching around the anus, especially at night when female worms lay their eggs. Some people have no symptoms. Other possible signs include disturbed sleep, irritability and visible small white thread-like worms around the anus or in stool. Occasionally, irritation can occur around the vulva or vagina.
How pinworms spread
Pinworm eggs can get onto fingers after scratching and then spread to the mouth, bedding, clothing, toys and household surfaces. Infection occurs when microscopic eggs are swallowed. Reinfection is common because the eggs can survive outside the body for a period of time.
Diagnosis
A clinician may recommend a tape test, usually performed in the morning before washing or using the toilet. Clear adhesive tape is pressed against the skin around the anus and then examined for eggs. Seeing characteristic worms can also support the diagnosis.
Treatment
Antiparasitic medicine can treat pinworm infection. Because medicines kill worms more effectively than eggs, a repeat dose is often needed after an interval specified for the particular medicine. Household members may need treatment at the same time depending on local recommendations and individual circumstances. Ask a pharmacist or healthcare professional about the appropriate medicine and dosing, especially for young children or during pregnancy or breastfeeding.
Preventing reinfection
- Wash hands carefully after using the toilet and before eating or preparing food.
- Keep fingernails short and discourage nail biting and scratching.
- Shower in the morning and change underwear daily during treatment.
- Wash sleepwear, towels and bedding regularly and avoid shaking them before washing.
- Clean frequently touched bathroom and bedroom surfaces.
- Do not share towels or washcloths.
Human pinworms do not come from household pets, so pets do not need treatment for human pinworm infection.
When to get medical advice
Contact a healthcare professional if you are unsure of the diagnosis, symptoms continue despite correctly completed treatment, the skin becomes very sore or infected, or symptoms are unusual or severe.
This page provides general health information and does not replace individual medical assessment or treatment.
Sources and further reading
Last reviewed: 28 September 2026.