The symptoms of pinworm (Enterobius vermicularis) infection can vary from person to person and depending on the severity of the infection. The most common symptoms caused by pinworms living in the intestines include:

- Intense Anal Itching: Severe itching around the anus, especially at night, triggered by female pinworms migrating to the anus to lay their eggs.
- Visible Worms: Small, white, thread-like worms that may be seen around the anus or in stool.
- Sleep Disturbances: Difficulty falling asleep, restlessness, and waking up at night due to discomfort caused by itching.
- Digestive System Symptoms: Abdominal pain, nausea, occasional watery diarrhea or constipation, gas, and bloating.
- Vaginal Symptoms in Women: Rarely, vaginal itching and discharge if pinworms migrate to the vagina.
- Behavioral and General Symptoms: Irritability due to constant itching, teeth grinding (bruxism), loss of appetite, inability to gain weight, and anemia in prolonged infections.

It is important to seek medical attention if these symptoms are noticed.