Can Worms or Parasites Cause Anemia?

Yes, some can. Hookworm, and heavy whipworm infections, can cause iron-deficiency anemia, because the worms lead to slow blood loss in the intestine; the CDC lists anemia among the effects of heavy hookworm infection. Most other common worms, including pinworm, are not usually linked to anemia, and in adults anemia has many causes that have nothing to do with worms.

This page explains which worms are linked to anemia and why, the signs to notice, how a clinician checks for both problems, and when to get care in person. It is general education, not medical advice.

How worms can lead to anemia

Anemia means your blood doesn't have enough healthy red blood cells to carry oxygen around the body. MedlinePlus explains that iron is a key part of red blood cells, and that iron-deficiency anemia develops when the body's iron stores run low, often because you lose more blood and iron than your body can replace.

Certain intestinal worms cause exactly that kind of slow, ongoing loss:

• Feeding on blood. The CDC explains that adult hookworms attach to the wall of the small intestine and feed on blood. Each worm takes only a little, but many worms over months add up.
• Losing iron and protein. The World Health Organization notes that soil-transmitted worms feed on host tissues, including blood, which leads to a loss of iron and protein, and that hookworms also cause chronic intestinal blood loss.
• Absorbing less from food. The WHO adds that these worms can reduce how well nutrients are absorbed and can lower appetite, so less iron comes in while more is lost.

The key word is heavy. The CDC and WHO both describe light infections, with only a few worms, as usually causing no symptoms. Anemia is mostly a problem of heavy or long-lasting infections.

Which worms are linked to anemia

Not every worm causes anemia. Here is how the common ones compare, based on CDC and MedlinePlus information:

• Hookworm: the classic cause. The CDC calls anemia and protein deficiency from blood loss the most serious effects of hookworm infection. MedlinePlus lists iron-deficiency anemia, caused by loss of blood, as a possible complication. Hookworm is usually caught when larvae in contaminated soil go through bare skin. See hookworm in humans.
• Whipworm: with heavy infections. The CDC lists severe anemia among the serious problems heavy whipworm infections can cause, especially in children, along with frequent, painful bowel movements that may contain mucus, water and blood. See whipworm in humans.
• Roundworm (Ascaris): not a typical cause. The CDC describes belly discomfort, cough while larvae move through the lungs, and, with heavy infections, blocked intestines and slowed growth in children. It doesn't list anemia as a usual sign, though the WHO notes these worms as a group can affect nutrition. See roundworm in humans.
• Pinworm: not linked to anemia. The CDC describes pinworm symptoms as usually mild, mainly itching around the anus at night, trouble sleeping and sometimes belly pain. Anemia is not among them. See pinworm treatment for adults.
• Blood parasites: a different route. Some parasites live in the blood rather than the gut. MedlinePlus lists anemia among the main features of malaria, for example. Malaria is not a worm, and Get It Prescribed does not treat it.

Signs of anemia to notice

Anemia often develops slowly, so it can be easy to miss. MedlinePlus says mild anemia may cause no symptoms. When symptoms appear, MedlinePlus and the National Heart, Lung, and Blood Institute (NHLBI) list signs such as:

• Feeling weak or tired more than usual, or tired with exercise
• Headaches, dizziness or feeling lightheaded when you stand up
• Pale skin
• Shortness of breath or a racing or pounding heartbeat
• Cold hands and feet
• Brittle nails or a sore tongue as it gets worse
• Cravings to eat ice or other non-food things (called pica)

When worms are the cause, you may also notice signs of the worm infection itself. With hookworm that can include an itchy rash where larvae entered the skin, belly pain, diarrhea, loss of appetite and weight loss. With heavy whipworm it can include frequent, painful bowel movements with mucus or blood. Our guide to intestinal worms in adults covers the signs of each worm.

Worms are only one cause of iron-deficiency anemia

If a blood test shows iron-deficiency anemia, worms are one possibility among many. MedlinePlus and the NHLBI list common causes such as:

• Heavy, long or frequent menstrual periods, or bleeding during childbirth
• Bleeding in the stomach or intestines, for example from ulcers, inflammatory bowel disease, long-term use of aspirin or ibuprofen, or cancer of the digestive tract
• Problems absorbing iron, such as celiac disease, Crohn's disease or stomach surgery
• Not getting enough iron in the diet, or needing more iron, for example during pregnancy

Because some of these causes are serious, unexplained iron-deficiency anemia in an adult should be looked into by a clinician rather than put down to worms. Worms become a more likely explanation when there is a reason to suspect them, such as time spent in places where hookworm is common, walking barefoot on soil that may be contaminated with human feces, or digestive symptoms that started after travel. Our guide to parasites from traveling explains those risks.

How a clinician checks for worms and anemia

Two different tests answer two different questions:

• A blood count checks for anemia. MedlinePlus explains that anemia is diagnosed with a complete blood count (CBC), and that iron levels, such as ferritin, show whether low iron is the reason. A CBC can also show raised eosinophils, a type of white blood cell that often goes up with worm infections, but it cannot name the worm. See can a blood test detect parasites.
• A stool test checks for the worms. The CDC says a stool sample examined under a microscope for eggs is the only way to know for sure that you have a hookworm or whipworm infection. Our guide to the stool test for parasites explains how it's done.

For iron-deficiency anemia, MedlinePlus notes that a provider may also order tests to look for a source of bleeding, such as a test for hidden blood in the stool, an upper endoscopy or a colonoscopy. Our guide to what a colonoscopy can show about parasites explains where it fits. Which tests you need depends on your age, symptoms and history.

What treatment involves

When worms and anemia show up together, a clinician usually deals with both. The CDC and MedlinePlus describe prescription anti-worm medicines, such as mebendazole, for hookworm and whipworm. The CDC notes that people with anemia are often prescribed iron as well, and MedlinePlus says a provider may suggest more protein in the diet.

The choice of medicine, the dose and how long to take it are the prescriber's decision. We don't publish doses or schedules. Don't start iron on your own without asking a clinician first, since the right approach depends on what your blood tests show and what is causing the anemia.

Get in-person care promptly if you have black or tarry stools or blood in your stool, fainting, chest pain, severe shortness of breath, a racing heart at rest, severe or worsening belly pain, or a fever after travel abroad. In-person care is also the right route if you are pregnant or breastfeeding, or if the person with symptoms is a child.

Getting a prescription through Get It Prescribed

Get It Prescribed is a telehealth service for adults. A licensed provider reviews a written health assessment, including any test results you already have, and decides whether mebendazole or ivermectin is appropriate for a labeled use. Mebendazole's labeled uses are pinworm, whipworm, roundworm and hookworm; ivermectin's are intestinal strongyloidiasis and onchocerciasis. Get It Prescribed does not diagnose or treat anemia itself, and does not treat malaria or other blood parasites. No prescription is guaranteed, and the provider may recommend testing or an in-person visit instead. How it works shows each step.

The medicines dispensed through Get It Prescribed are compounded preparations made by a licensed compounding pharmacy. They are not FDA-approved, the FDA has not reviewed them for safety, effectiveness or quality, and they are not generics of, or substitutes for, the brand-name products.

The cost is a one-time $50 provider consultation fee, plus $3.00 per ivermectin tablet or $3.50 per mebendazole capsule if a prescription is issued, with the quantity decided by the provider. The service is available in all 50 states and the District of Columbia; some states require a live phone or video visit.

This article is general education, not medical advice. It does not replace an evaluation by a licensed clinician who knows your history.

Related questions

Which parasites cause iron-deficiency anemia?

Hookworm is the best-known cause, because the worms feed on blood in the small intestine. Heavy whipworm infections can also cause anemia, especially in children. Some blood parasites, such as malaria, cause anemia by a different route.

Can pinworms cause anemia?

Pinworms are not linked to anemia. The CDC describes pinworm symptoms as usually mild, mainly itching around the anus at night, with trouble sleeping and sometimes belly pain. If you have anemia and pinworms, a clinician will look for another cause of the anemia.

Can roundworms cause anemia?

The CDC doesn't list anemia as a usual sign of roundworm (Ascaris) infection. Heavy infections can affect nutrition and slow growth in children, and the WHO notes that this group of soil-transmitted worms can reduce how well nutrients are absorbed.

Should I get tested for worms if I have iron-deficiency anemia?

Ask your clinician. Worms are one possible cause, and are more likely if you have spent time where hookworm is common or walked barefoot on contaminated soil. Many other causes, including bleeding in the gut, need to be checked too, so a stool test is usually one part of a wider workup.

Can a CBC show worms?

Not directly. A complete blood count can show anemia and raised eosinophils, which can be clues to a worm infection, but it can't identify the worm. A stool test is how hookworm and whipworm are usually confirmed.

Sources

• CDC: About Hookworm — blood loss, anemia and protein deficiency as the most serious effects; stool test for diagnosis; iron for people with anemia.
• CDC: About Whipworms — severe anemia with heavy infections, especially in children.
• CDC: About Ascariasis — roundworm symptoms and diagnosis.
• CDC: About Soil-transmitted Helminths — blood and protein loss with heavy infections; stool exam for diagnosis.
• CDC: About Pinworm Infection — pinworm signs and symptoms.
• WHO: Soil-transmitted helminth infections — loss of iron and protein, chronic blood loss from hookworm, reduced nutrient absorption.
• MedlinePlus: Hookworm infection — iron-deficiency anemia as a complication; CBC and stool tests.
• MedlinePlus: Whipworm infection — whipworm infection overview.
• MedlinePlus: Iron deficiency anemia — causes, symptoms and tests for iron-deficiency anemia.
• NHLBI: Iron-Deficiency Anemia — symptoms and causes of iron-deficiency anemia.
• MedlinePlus: Malaria — anemia as a feature of malaria.
• DailyMed: mebendazole chewable tablet prescribing information — labeled uses: pinworm, whipworm, roundworm and hookworm.
• FDA: Compounding and the FDA — Questions and Answers — what compounded preparations are and how they are regulated.