Intestinal Worms & Parasites

Infection usually happens by swallowing eggs or cysts from contaminated food, water, soil or hands, or by eating undercooked meat or fish that contains parasite larvae. Some worms, such as hookworm, enter through the skin when walking barefoot on contaminated soil. Poor hand washing, especially in children, spreads infection within families and schools.

These infections are found worldwide and are more common where clean water and sanitation are limited, in crowded settings, and among young children. Pinworm is common in children everywhere, including in settings with good sanitation.

Travel, workers living in shared accommodation, and eating raw salad or undercooked food away from home can increase exposure. Washing produce and using safe water is advised.

Diagnosis is usually by examining stool samples under the microscope or with special stool tests for the parasite; more than one sample may be needed. Pinworm is often found with a tape test around the anus in the morning. Blood tests may show anemia or raised eosinophils (a type of white blood cell that rises with some parasites). Imaging or endoscopy is only used in selected cases.

Hygiene is the most effective prevention.

• Wash hands with soap and water after the toilet, after changing diapers, and before eating or cooking.

• Keep children's nails short and discourage nail biting and thumb sucking.

• For pinworm, wash bedding, underwear and towels in hot water and shower in the morning.

• Wear shoes outdoors in areas with contaminated soil.

Safe food and water handling prevents most infections.

• Drink safe, treated or boiled water.

• Wash and peel fruit and vegetables; wash salad leaves carefully.

• Cook meat and fish thoroughly, and avoid raw or undercooked meat.

• Eat iron-rich foods and have your iron checked if anemia is found.

Anti-parasitic medicines are effective, but the right one depends on the parasite.

• Your doctor will choose the medicine, dose and duration after identifying the parasite.

• For some worms such as pinworm, a repeat course after a couple of weeks and treating the household may be advised.

• Do not use over-the-counter or herbal "worm cleanses" in place of medical treatment.

• Pregnant women and young children need medicines chosen specifically for them; always ask a doctor first.

• Iron supplements may be given for anemia.

Procedures are rarely needed.

• Endoscopy or colonoscopy may be done if the cause of symptoms is unclear, and sometimes a worm is seen and removed.

• Bowel blockage or complications in the bile ducts from heavy worm infection may need hospital care and sometimes endoscopic or surgical treatment.

Most infections clear completely after the right treatment. Re-infection is common if hygiene and the source of exposure do not change, so household measures are important, and in some cases the whole family is treated together.

• Which parasite do I have, and which medicine is right for it?

• Does my family need treatment or testing?

• Do I have anemia or low iron because of this infection?

• Do I need a repeat stool test after treatment?

• How can I prevent re-infection at home and school?

This guide comes from the Saudi Gastroenterology Association (SGA) patient library, prepared by the Approved for publication by SGA; individual clinician review is ongoing. Last reviewed: 2026-04-24. It is for education and does not replace your doctor's advice.