Roundworm in Humans: Symptoms, Treatment

Roundworm in humans is an intestinal infection, most often with Ascaris lumbricoides, that people catch by swallowing tiny eggs from soil, food or water contaminated with human stool. Roundworm symptoms in humans range from none at all to belly pain, a cough or passing a worm in the stool, and roundworm treatment for humans is a prescription anti-worm medicine, such as mebendazole or albendazole, chosen by a clinician.

The CDC calls Ascaris the most common worm parasite found in humans. The infection is also called ascariasis. This page covers that human intestinal roundworm. Roundworms caught from dogs or cats are a different infection, covered further down.

How do humans get roundworm?

The CDC explains that a person with Ascaris passes the eggs in their stool. Where human waste reaches the soil, through outdoor defecation, poor sanitation or the use of human waste as fertilizer, the eggs develop over time into a form that can infect people.

You get roundworm by swallowing those infective eggs, for example:

• Eating raw fruits or vegetables grown in contaminated soil that were not washed, peeled or cooked
• Putting hands in your mouth after touching contaminated soil, which is why young children are infected most often
• Drinking water contaminated with human waste

Roundworm does not spread directly from person to person through touch. Freshly passed eggs are not yet infective; they need time in soil first.

What happens inside the body

MedlinePlus describes the life cycle. Once swallowed, the eggs hatch in the small intestine and release larvae. Within a few days the larvae travel through the bloodstream to the lungs, move up the airways, and are swallowed back down to the small intestine, where they grow into adult worms. Adult roundworms are large, and MedlinePlus notes they can live in the intestine for 10 to 24 months, laying eggs that pass out in the stool.

Roundworm symptoms in humans

According to the CDC and MedlinePlus, most people with roundworm have few or no symptoms. When symptoms happen, they depend on where the worms are:

• While the larvae pass through the lungs: a cough, wheezing, shortness of breath or a low fever. MedlinePlus notes that, uncommonly, this stage causes a type of pneumonia linked to raised eosinophils, a kind of white blood cell.
• Once the worms live in the intestine: belly discomfort or pain, nausea or vomiting, and in some cases passing a worm in the stool
• Heavy infections: the CDC says these are more common in children and can block the intestine and slow a child's growth

Some people only find out they have roundworm when they see a worm in their stool, or cough one up. Our guide to worms in stool shows how a roundworm differs from other worms. The CDC advises bringing the worm to a healthcare provider so it can be identified.

When roundworm becomes serious

Most infections are mild, but a large number of worms can cause problems. MedlinePlus lists possible complications, including a blocked intestine, blocked bile ducts in the liver, appendicitis and, rarely, a hole in the gut. These complications need urgent, in-person medical care.

Seek emergency care for severe or worsening belly pain, a swollen belly, repeated vomiting, being unable to pass stool or gas, yellowing of the skin or eyes, or vomiting a worm.

Who is at risk?

The CDC says most cases occur in tropical and subtropical parts of Asia, sub-Saharan Africa and the Americas, where sanitation is limited, and it estimates that hundreds of millions of people are infected worldwide. Children are infected most often and are affected more severely than adults.

In the United States, modern sanitation makes roundworm uncommon. Your risk is mainly tied to living in, or traveling to, places where the infection is common, especially if you ate raw produce there.

What about roundworm from dogs or cats?

Dog and cat roundworms are a different parasite, Toxocara. The CDC explains that people can catch it by swallowing eggs from soil contaminated with dog or cat feces, and that it causes an infection called toxocariasis, which can affect the liver, lungs or eyes rather than living in the intestine. It does not spread from person to person.

Toxocariasis is not what mebendazole's labeling covers, and it is not treated through Get It Prescribed. If you think you or your child caught roundworm from a pet, especially with eye symptoms, fever or wheezing, see a clinician in person.

How roundworm is diagnosed

The CDC says a healthcare provider can examine a stool sample under a microscope for Ascaris eggs. MedlinePlus adds that a clinician may order a blood count, including an eosinophil count, and sometimes an x-ray or other imaging if a blockage is suspected. Symptoms alone are not enough to tell roundworm apart from other causes of stomach upset. See what a stool test for parasites involves.

How roundworm is treated

Roundworm is treated with prescription anti-worm medicine chosen by a clinician. MedlinePlus names albendazole among the medicines used. The prescribing information for the brand-name mebendazole chewable tablet lists the common roundworm, Ascaris lumbricoides, among its labeled uses, alongside pinworm, whipworm and hookworm. For background on the medicine, see what is mebendazole and how does it work. Its labeling does not cover tapeworms or flukes; see which parasites mebendazole's labeling covers.

Your clinician decides whether a follow-up stool check is needed and what happens next. Large blockages caused by many worms may need a procedure to remove them.

The dose and length of treatment are the prescriber's decision. We don't publish doses or schedules, and you should follow the directions on your own prescription label. Possible side effects are covered in mebendazole side effects.

Preventing roundworm

The CDC recommends:

• Washing your hands with soap and water after using the toilet and before handling food
• Washing, peeling or cooking raw fruits and vegetables
• Avoiding soil or water that may be contaminated with human waste
• Teaching children to wash their hands, since they are infected most often

Getting roundworm treatment online

If you have been diagnosed with roundworm, or a clinician suspects it based on your history and test results, a licensed provider can review your health assessment through Get It Prescribed and decide whether mebendazole is appropriate. There is a one-time $50 consultation fee, and mebendazole costs $3.50 per capsule; the prescriber decides the quantity. The service is available in all 50 states and the District of Columbia, and some states require a live phone or video visit. How it works shows each step. A prescription is never guaranteed.

The mebendazole dispensed through Get It Prescribed is a compounded preparation made by a licensed compounding pharmacy for an individual patient. Compounded preparations are not FDA-approved, and the FDA does not review them for safety, effectiveness or quality. They are not generics of, or substitutes for, the brand-name product.

See a clinician in person instead if you are pregnant or breastfeeding, are treating a young child, have severe belly pain or vomiting, or think the infection came from a pet.

Related questions

What are the symptoms of roundworm in humans?

Many people have none. When symptoms occur, they can include a cough or wheezing while the larvae pass through the lungs, then belly pain, nausea or vomiting once the worms are in the intestine. Some people first notice a worm in their stool. Heavy infections, more common in children, can block the intestine and slow growth.

How do humans get roundworm?

By swallowing roundworm eggs from soil, food or water contaminated with human stool, for example by eating unwashed raw produce or putting dirty hands in the mouth. The eggs must spend time in soil before they can infect anyone, so roundworm does not spread directly from person to person.

What is the treatment for roundworm in humans?

Prescription anti-worm medicine, such as mebendazole or albendazole, chosen by a clinician. A stool test confirms the diagnosis, and a clinician may order a follow-up stool check afterward.

Is roundworm medicine for humans available over the counter?

Not in the US. Mebendazole needs a prescription from a licensed clinician. Some over-the-counter worm medicines are labeled for pinworm only, so they are not a substitute for a clinician's diagnosis of roundworm.

What does it mean to find a roundworm in human stool?

A roundworm seen in stool is much larger than a pinworm. The CDC says people with a heavy infection may pass a worm in their stool or cough one up, and advises bringing the worm to a healthcare provider so it can be identified. A stool test can then look for eggs. See worms in stool for how roundworm compares with other worms.

Can humans get roundworm from dogs or cats?

Yes, but it is a different infection. Dog and cat roundworms cause toxocariasis, which can affect the liver, lungs or eyes rather than the intestine. It is not covered by mebendazole's labeling. See a clinician in person if you think you caught roundworm from a pet.

Sources

• CDC: About Ascariasis — how people get human roundworm, symptoms, diagnosis, prevention and treatment.
• CDC: About Soil-transmitted Helminths — roundworm, whipworm and hookworm, how they spread and how they are treated.
• CDC: About Toxocariasis — dog and cat roundworm infection in people.
• MedlinePlus: Ascariasis — National Library of Medicine overview, including life cycle, complications and follow-up testing.
• MedlinePlus: Mebendazole — consumer drug information from the National Library of Medicine.
• DailyMed: mebendazole chewable tablet prescribing information — labeled uses, including the common roundworm.
• WHO: Soil-transmitted helminth infections — global background on roundworm and related worms.
• FDA: Compounding and the FDA — Questions and Answers — what compounded preparations are and how they are regulated.