Symptoms of Parasites: 7 Signs (with Online Symptom Test)

Updated in November 2023

The main symptoms of pinworms are anal itching, especially at night, the presence of blood on the toilet paper when wiping, pain or difficulty defecating, and the presence of small white dots in the stool.

The intense itching at night happens because the female worms travel to the anus to lay their eggs in the perianal region, causing symptoms and potentially making it difficult to sleep.

For this reason, in the presence of signs and symptoms of a pinworm infection, it is recommended that a general practitioner or gastroenterologist be consulted so that a diagnosis can be made. Treatment involves the use of antiparasitic drugs.

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Main symptoms

The main symptoms of pinworms are:

  • Blood on the toilet paper
  • Presence of small white dots in the stool
  • Scaling and redness in the anus
  • Pain or difficulty defecating
  • Itching during or after starting antibiotics
  • Itching that appears or worsens after shaving, using some kind of underwear, tampon or unprotected anal intercourse;
  • Sleep disturbances due to intense itching at night.

In addition, very large infestations of parasites can cause more symptoms like weight loss, nausea, irritability, vomiting and abdominal cramps. See other symptoms of intestinal worms

In women, the infection can also contaminate the vaginal tract, leading to vaginitis and even infertility if the parasites multiply in the fallopian tubes and cause obstructions. If the parasite travels up the intestine, it can reach the appendix and cause acute appendicitis, although this is not very common.

Online symptom test

If you have anal itching, report your other symptoms to determine your risk for pinworms:


The symptom test is only a guidance tool and does not serve as a diagnosis or replace a visit to the doctor.

Confirming a diagnosis

The diagnosis of pinworms is made by a general practitioner, gastroenterologist or pediatrician. It is confirmed with an assessment of the signs and symptoms presented by the person, an inspection of the anal region (where in some cases it is possible to see the presence of the worm), and diagnostic tests aimed at identifying eggs of the parasite Enterobius vermicularis.

The test for pinworms is popularly known as the tape test, and consists of sticking an adhesive tape to the perianal region, preferably in the morning before the person washes or defecates, and then observing it microscopically. The eggs can often be seen through a microscope. 

Although this method is widely used, it can spoil the eggs and limit other laboratory processes. For this reason, the collection of the skin sample should be done using a swab, which is then passed onto the slide and taken away for observation.

Treatment options

If pinworms are confirmed, the doctor may recommend the use of worm medicines such as albendazole or mebendazole, taken in a single dose to promote the elimination of the virus. 

When a person is infected with pinworms, clothes and bedding may contain eggs and can lead to further contamination or transmission to others.

Therefore, it is important that pinworm cases detected in a household be additionally treated with specific hygiene precautions, such as washing clothes and bedding separately at a high temperature and avoiding sharing towels, for example. It is also recommended that the whole family undergoes treatment, even if they do not present with symptoms.