What are the symptoms of intestinal worms in humans?

Updated June 13, 2017

Intestinal worms, including Ascaris, tapeworms and pinworms, are common parasitic infections that can occur in anyone, but certain risk factors increase the risk, such as swimming in contaminated water, drinking unfiltered water and poor hygiene. Intestinal worms are easily treated with medication prescribed by a doctor, and careful hygiene can prevent the spread of worms within a household.

Digestive Problems

People with intestinal worms may experience digestive changes, including loss of appetite or nausea when presented with food. If a large amount of worms accumulates in the intestines, the intestines can become obstructed, which can result in constipation. Intestinal worms can also cause diarrhoea, which may be bloody. Adult worms might be present in the faeces.


Tapeworm infections can cause people to develop abdominal pains and cramping. They might also have muscle aches and weakness when the adult worms migrate through their bodies. Girls and women with pinworms may have pain around the genitals and urinary tract, and severe infections can lead to pelvic inflammatory disease, which can cause chronic pelvic pain.

Respiratory Problems

People infected with the intestinal worm Ascaris may experience difficulty breathing. If the worms invade the lungs, those infected may have cough frequently. People with Ascaris infections may also experience pain when taking a deep breath and may have trouble breathing during physical activity or exercise.

Skin Changes

People with pinworm infections may experience intense itching around the anus, especially at night. Girls and women with pinworm infections may also have irritations and itching of the skin around the genitals and inside the vagina if the worms migrate from the anus. People with tapeworm infections may develop allergic skin reactions such as swelling, redness and hives, if the larvae embed into their skin.

Weight Loss

Babies infected with Ascaris may experience a lack of growth in height and weight, which is also referred to as failure to thrive. Adults infected with pinworms, tapeworms or Ascaris may also experience weight loss. Nutritional deficiencies also may develop in people infected with intestinal worms as a result of heavy infestations or worms that grow to be very large.


Intestinal worms can be prevented by drinking filtered water, swimming in chlorinated pools and careful hygiene, especially after contact with faeces. People who are infected with intestinal worms can be treated by a medical doctor with prescription medications. People with intestinal worm infections should take care to launder all towels, linens and clothing that come into contact with their bare skin so as to avoid reinfection.

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About the Author

Jessica Lietz has been writing about health-related topics since 2009. She has several years of experience in genetics research, survey design, analysis and epidemiology, working on both infectious and chronic diseases. Lietz holds a Master of Public Health in epidemiology from The Ohio State University.