Intestinal worms are organisms that feed off the human body. Tapeworm, hookworm, pinworm, and other types of worms affect the body in different ways. A person may notice worms in stool.

Types of intestinal worms include tapeworm, hookworm, liver fluke, threadworm, Ascaris, which causes ascariasis, and Trichinella, which causes trichinosis.

Intestinal worms can cause many symptoms, and some of these resemble the symptoms of other gut conditions. A prompt, accurate diagnosis can prevent complications. Most cases respond well to treatment, which usually involves medication.

This article looks at different types of intestinal worms, the symptoms they cause, who is at risk, and the treatment available.

The symptoms of intestinal worms can vary between individuals and depend on the type of worm present. Potential symptoms include:

Some types of worm, including some tapeworms, can affect the central nervous system, with potentially severe consequences.

Worms can enter the body in various ways, depending on the type. Sanitation problems often play a role, but intestinal worms can happen anywhere.

Factors that increase the risk of worm infections include:

  • eating raw meat or fish
  • poor hygiene
  • having inadequate access to sanitation or clean water
  • living in a hot or tropical climate
  • having a low income

Pinworms, the most common type of worms in the U.S., are more common in places where people live or spend time closely together, such as child care settings and residential care homes.

Various types of intestinal worms can affect human health, such as:


A tapeworm is a type of flatworm that lives in the intestine, where it attaches itself to the intestinal wall.

The Centers for Disease Control and Prevention (CDC) estimate that fewer than 1,000 new cases of tapeworms occur each year in the U.S.

There are several types, including:

  • Taenia solium (T. solium): This type comes from raw or undercooked pork. It is more common in South America, Eastern Europe, sub-Saharan Africa, India, and Asia, but it also occurs in the U.S.
  • T. asiatica: This type comes from beef or pork and mostly occurs in Korea, China, Taiwan, Indonesia, and Thailand.
  • T. saginata: This type comes from undercooked beef or pork and occurs mainly in places where people eat raw beef, such as Eastern Europe, Russia, eastern Africa, and South America.

Tapeworm eggs can also be present in water and may enter the body if a person consumes contaminated water.

Symptoms of tapeworm

Most people with tapeworm have no symptoms, or only mild symptoms. If symptoms do occur, they may include:

  • pain
  • loss of appetite
  • weight loss
  • dizziness
  • upset stomach
  • passing fragments of tapeworm in the stool

According to the World Health Organization (WHO), though, only T. solium tapeworms cause significant health problems. Without treatment, T. solium larvae can cause cysts in the skin, eyes, muscles, and nervous system. In the brain, they can lead to:

Experts believe that in areas where it occurs, T. solium is responsible for up to 70% of epilepsy cases.

Treatment for tapeworms

Praziquantel (Biltricide) can remove a tapeworm. This drug paralyzes the worm, forcing it to detach from the intestinal wall. It then helps dissolve the worm so it can pass through the digestive system and leave the body during a bowel movement.


Hookworms live in the small intestine. Their name refers to how one end of the body tapers off into a needle or hook shape.

Hookworms enter the body through the skin — for instance, if a person walks barefoot on contaminated soil. Once inside, they find their way to the small intestine and lay eggs. A person can pass them on through defecating outdoors, such as in bushes, or by using feces as fertilizer.

One type of hookworm can also enter the body if a person consumes the larvae in food or on the hands.

According to the CDC, hookworm affects around 576–740 million people worldwide. In the past, hookworm was common in the southeastern U.S., but numbers have fallen due to improvements in living conditions.

Symptoms of hookworm

Most people with hookworm have no symptoms. Some individuals may have gastrointestinal symptoms, especially with a first-time infection. More serious complications include protein loss and anemia due to blood loss.

Treatment for hookworm

Doctors may prescribe medications such as albendazole and mebendazole to treat hookworm, usually for 1–3 days.


Flukes are a type of flatworm. They can affect the lungs, intestines, liver, and other parts of the body. Liver flukes affect the liver, gallbladder, and bile duct.

Two types of liver fluke, Clonorchis and Opisthorchis, can enter the body when a person eats contaminated raw or undercooked:

  • fish
  • crabs
  • crawfish

Another liver fluke, Fasciola, can occur anywhere there are sheep or cattle. The larvae can enter the body if a person eats contaminated watercress or other water plants.

Symptoms of flukes

Most people with flukes will not have symptoms, but an infection that lasts a long time can lead to severe symptoms and complications. Without treatment, infection can last for up to 25–30 years, which is the life span of these parasites.

If a person has symptoms, they may experience:

Treatment for flukes

Treatment for flukes involves taking medications. For many flukes, the drugs of choice are praziquantel. For Fasciola, it is triclabendazole.


A pinworm is a small, thin roundworm around the length of a staple. They are relatively harmless and can live in the colon and rectum of humans.

A person can pass the worms on to someone else through direct contact or by sharing a contaminated object with them, such as food, clothing, or bedding. Bathing with others can also allow the eggs to spread.

Washing regularly can help prevent pinworm infection or re-infection. Showering is best, as this washes away any eggs down the drain.

Symptoms of pinworms

Many people with pinworm experience only mild symptoms. When symptoms do occur, a person may have itching around the anus, which can affect sleep.

Treatment for pinworms

Prescription and over-the-counter (OTC) medications can remove pinworm. A person will need two doses, one 2 weeks after the other. The whole household will need treatment.


Ascaris is one of the most common parasites globally, affecting up to 1.2 billion people around the world. It causes the disease ascariasis. It is uncommon in the U.S.

Ascaris is similar to a hookworm but only a few inches long. It lives in contaminated soil. It can enter the body when people ingest the eggs on fruits or vegetables that have not been carefully washed, peeled, or cooked. A person with Ascaris can pass on the eggs in feces.

Symptoms of ascariasis

Individuals with an ascariasis infection may have:

  • no symptoms
  • mild abdominal pain or discomfort
  • coughing and wheezing
  • intestinal blockage, in severe cases
  • liver blockages

It can also affect growth in children due to malnutrition.

Treatment for ascariasis

Antihelminthic drugs, which aim to remove worms from the body, can treat ascariasis. A doctor may prescribe albendazole or mebendazole for 1–3 days.


Trichinella are a type of roundworm. A person can ingest them by eating undercooked or raw meats from animals that eat also meat, such as pigs, as well as wild animals, such as:

  • bears
  • wild felines, such as cougars
  • fox
  • dog
  • wolf
  • horse
  • seal
  • walrus

Smoking or curing these meats does not effectively kill the worms, so people can also get trichinella from homemade jerky, sausage, and similar products.

Contaminated meat contains live larvae. The larvae then grow in the intestines. On reaching their full size, the Trichinella worms may leave the intestines and live in other tissues, such as the muscles.

Trichinella infection is relatively rare in the U.S., but it can affect those who eat game meats or hunt for food.

Symptoms fo trichinosis

This type of worm causes the disease trichinosis. Abdominal symptoms can appear 1–2 days after eating contaminated meat, and other symptoms can appear 2–8 weeks later.

Symptoms include:

Severe cases can be fatal.

Treatment for trichinosis

Prescription drugs can treat Trichinella infection. A person should seek medical help as soon as possible if they notice symptoms.

A person should seek medical advice if they:

  • have abdominal symptoms, such as diarrhea, lasting more than 2 weeks
  • lose weight unexpectedly
  • have itching around the anus
  • find a worm or piece of a worm on toilet paper or stool

Some antiparasitic medications are available over the counter, but people should speak with a health professional before using them to check they are the right drug.

Not all medications for parasites are not suitable for everyone. For example, some may not be safe during pregnancy. A doctor can advise on what to do in this situation.

To diagnose worms, a doctor may ask about a person’s symptoms, whether they have travelled recently, and dietary habits, such as whether they eat raw meat or fish.

Various tests can help diagnose intestinal worms, such as:

  • stool tests
  • blood tests
  • a colonoscopy, if stool tests do not show the cause of symptoms
  • imaging tests to check other organs for signs of damage
  • a tape test

For pinworms, the tape test may help with diagnosis. This involves using sticky tape to touch the skin around the anus to see if there are worms or eggs. A person should do this for 3 days on waking up. Always wash the hands before and after doing this.

Intestinal worms can sometimes lead to complications. How these affect the body will depend on the worm, but possible complications include:

  • anemia and other nutritional deficiencies, due to difficulty absorbing nutrients
  • intestinal blockage
  • problems with lung and heart function
  • human cysticercosis, which can result in vision loss and seizures

In some cases, the complications stemming from untreated parasites can be life threatening.

People can take steps to reduce the risk of having worms. Essential measures include:

  • washing the hands regularly, especially after using the bathroom and before handling food or eating
  • avoiding sharing clothing, bedding, and other personal items
  • avoiding walking barefoot in places where soil-transmitted worms are present
  • avoiding defecating in fields and other open places, where possible

Many intestinal worms enter the body through the food that a person eats. Some practices that may lower the risk include:

  • never eating undercooked or raw meats
  • cooking red meat and fish to an internal temperature of 145°F (62.7°C), ground meat to an internal temperature of 160°F (71.1°C), and poultry and leftovers to an internal temperature of 165°F (73.87°C)
  • using separate cutting boards for meats and vegetables
  • thoroughly washing and peeling all fruits and vegetables
  • using boiled or treated water for drinking and washing foods
  • freezing pork in pieces less than 6 inches thick for 20 days at 5°F (-15°C) to kill worms
  • cleaning meat grinders thoroughly after use.
  • avoiding swimming or bathing in water that may be contaminated

Note that freezing, salting, smoking, drying, and microwaving meat may not kill worms.

Below, we answer some questions people often ask about intestinal worms.

What does poop look like when you have worms?

In some cases, a person may have diarrhea, or notice a worm or part of a worm on feces. Often, however, there are no symptoms.

How do you treat intestinal parasites and get rid of worms?

A doctor will recommend medication after identifying which type of worm is present.

How do adults get worms?

Depending on the type of worm, people of any age can get worms from eating raw or undercooked meat or seafood, swimming in or drinking contaminated water, and walking barefoot in places where worms are present.

Sharing objects such as clothing or bedding and not washing the hands regularly also pose a risk.

What do intestinal worms feed on?

Intestinal worms and other parasites feed on nutrients inside the intestine. This can reduce the amount of nutrients a person’s body absorbs.

Do we all have intestinal worms?

No, this is a myth. Worm infections are more common in areas with a lack of sanitation and clean water, or in places where people eat raw or undercooked meat and fish as part of their diet.

How do you get rid of intestinal worms naturally?

There are few high quality studies on natural treatments for intestinal worms. A 2017 mouse study suggests that wormwood might help, but large trials in humans are necessary to confirm it is safe and effective.

Do we all need a parasite cleanse?

Intestinal worms are common worldwide. Different types occur in different places.

A person may be at risk of having worms for a number of reasons, such as consuming raw or undercooked meat or seafood, sharing personal items with others, drinking or swimming in contaminated water, walking barefoot outdoors, and not washing their hands regularly.

Some worms cause few or no symptoms, but some can cause severe complications over time.

Anyone who believes they may have an intestinal worm should contact a doctor as soon as possible for a diagnosis and prompt treatment. Effective treatment usually involves the use of medication.