Blood Clot in Stool: Causes, Signs, and When to Worry

Seeing a blood clot in stool can be frightening, especially if it happens without warning. In many cases, rectal bleeding is caused by a minor issue such as hemorrhoids or a small tear in the anus. But blood clots in the stool can also point to more serious problems, including bleeding higher up in the digestive tract. Understanding what the bleeding looks like, what may be causing it, and when it needs urgent medical attention can help you respond calmly and appropriately.

If you have ongoing bleeding or other warning signs, a doctor may also look for related causes such as bleeding symptoms and help in the digestive system or elsewhere in the body. The source of the problem is not always obvious from the toilet bowl alone, which is why details like color, amount, and accompanying symptoms matter so much.

What does blood clot in stool mean?

A blood clot in stool usually means that blood has pooled in the digestive tract long enough to thicken before passing out of the body. This can appear as dark red or maroon clumps in the stool, jelly-like pieces of blood, bright red blood mixed with stool, or blood on toilet paper or in the toilet bowl.

The color and appearance can offer clues about where the bleeding is coming from. Bright red blood often comes from the lower part of the digestive tract, such as the rectum or anus. Darker blood or clots may suggest bleeding from farther up in the colon or small intestine. In some cases, a blood clot in stool is just one episode after constipation, straining, or irritation. In other cases, it may be the first sign of a condition that needs treatment.

It is also helpful to pay attention to whether the blood appears on the surface of the stool, mixed throughout it, or separated from the stool entirely. Blood that coats the outside of stool often points to a lower source, while blood that is maroon, dark, or blended with stool can suggest the blood had more time to travel through the intestines. A bowel movement after constipation can sometimes cause a small amount of bleeding from a hemorrhoid or fissure, but repeated bleeding is not something to dismiss.

In practical terms, the phrase blood clot in stool does not always mean a true clot in the medical sense. People often use it to describe thick, clumped, or jelly-like blood seen in the toilet. Even if the wording is informal, the symptom still deserves attention because it may reflect active bleeding somewhere in the gut.

Common causes of blood clots in stool

There are several possible causes of a blood clot in stool, ranging from mild to serious. The most common include hemorrhoids, anal fissures, diverticular bleeding, inflammatory bowel disease, colon polyps or colorectal cancer, gastrointestinal infection, upper gastrointestinal bleeding, and the use of medications that increase bleeding risk.

1. Hemorrhoids

Hemorrhoids are swollen blood vessels in the rectum or anus. They are one of the most common causes of rectal bleeding.

Typical signs:

• Bright red blood on stool or toilet paper
• Itching or discomfort around the anus
• A lump near the anus
• Mild pain during bowel movements

Hemorrhoids usually cause small amounts of bleeding rather than large clots, but heavier bleeding can sometimes lead to clotting. Straining, sitting for long periods on the toilet, and constipation can make them worse. If you want more detail on this cause, see Bleeding Hemorrhoid: Causes, Relief, and When to Worry.

External hemorrhoids may feel tender or swollen, while internal hemorrhoids are more likely to cause painless bleeding. Either type can flare when bowel movements are hard or frequent. Drinking enough water, adding fiber, and avoiding excessive straining may help reduce symptoms, but new or repeated bleeding should still be evaluated.

2. Anal fissures

An anal fissure is a small tear in the lining of the anus, often caused by passing hard or large stools.

Typical signs:

• Sharp pain during bowel movements
• Bright red blood
• Streaks of blood on stool or toilet paper

Fissures do not usually cause large clots, but they can still lead to visible blood in the stool. The pain is often described as burning or tearing and may last for a while after the bowel movement ends. People with constipation or a history of repeated straining are more likely to develop fissures.

When a fissure is present, the bleeding is usually small, yet the pain may feel intense. Warm sitz baths, stool softeners, and avoiding hard stools often help, but persistent symptoms should be checked if they do not improve.

3. Diverticular bleeding

Diverticula are small pouches that can form in the wall of the colon. Sometimes one of these pouches bleeds, causing sudden and sometimes heavy rectal bleeding.

Typical signs:

• Large amounts of bright red or maroon blood
• Blood clots in stool
• Little or no pain

Diverticular bleeding can be significant and may require prompt medical evaluation. Because it may happen suddenly and without pain, people are sometimes surprised by the amount of blood they see. In some cases, the bleeding stops on its own, but it can also recur.

Diverticular disease becomes more common with age, and a person may have no warning before the first episode. If the bleeding is heavy or repeated, doctors may recommend urgent testing to identify the source and prevent further blood loss.

4. Inflammatory bowel disease

Conditions such as ulcerative colitis and Crohn’s disease can cause inflammation and bleeding in the digestive tract.

Typical signs:

• Blood in stool
• Diarrhea
• Abdominal pain
• Urgency to have a bowel movement
• Weight loss or fatigue

Blood clots may appear if the bleeding is more than mild. These conditions can also cause mucus in the stool, cramps that come and go, and a feeling that the bowel movement is incomplete. Flares may happen in cycles, with periods of improvement followed by sudden worsening.

Inflammatory bowel disease often needs ongoing medical care. If blood in stool is part of a pattern of chronic diarrhea, pain, and fatigue, it should not be ignored.

5. Colon polyps or colorectal cancer

Polyps are growths in the colon that may bleed. In some cases, colorectal cancer can also cause bleeding.

Typical signs:

• Blood in stool, which may be bright red or dark
• Change in bowel habits
• Unexplained weight loss
• Ongoing abdominal discomfort
• Fatigue or anemia

Because these conditions can be serious, any unexplained blood in the stool should be taken seriously, especially if it keeps happening. Not every polyp or cancer causes pain, which is one reason rectal bleeding should never be self-diagnosed without evaluation.

The risk rises with age and with certain family histories. Screening tests are designed to find these problems early, sometimes before symptoms begin. If bleeding is new or you have a change in bowel habits, it is important to mention that to a healthcare professional as soon as possible.

6. Gastrointestinal infection

Some bacterial infections can cause inflammation and bleeding in the intestines.

Typical signs:

• Diarrhea, sometimes with blood
• Fever
• Stomach cramps
• Nausea or vomiting

If blood clots in stool appear along with diarrhea and fever, an infection may be the cause. Travel, contaminated food, sick contacts, and recent antibiotic use can all provide important clues. Infections may also cause dehydration, which can make symptoms feel worse and bowel movements harder to pass.

Because bloody diarrhea can sometimes spread to other people, handwashing and careful food handling matter. Still, the priority is figuring out why the bleeding is happening, especially if symptoms are severe or the person is becoming weak.

7. Upper gastrointestinal bleeding

Bleeding from the stomach or small intestine can sometimes travel through the digestive system and appear as dark stool or clots.

Typical signs:

• Black, tarry stool
• Dark red blood in stool
• Vomiting blood
• Dizziness or weakness

For an overview of symptoms that may point to bleeding higher in the gut, you can also review MedlinePlus information on blood in stool.

Upper gastrointestinal bleeding can come from ulcers, irritation of the stomach lining, or other sources higher in the digestive tract. The blood may look very different from the bright red bleeding people associate with hemorrhoids. Black stool does not always mean an emergency, but when it appears with weakness, fainting, or vomiting, it needs urgent attention.

8. Use of blood thinners or certain medications

Medications such as aspirin, ibuprofen, and prescription blood thinners can increase the risk of bleeding in the digestive tract.

These medications may not directly cause the problem, but they can make even small sources of bleeding more noticeable. In some people, medication use can turn a small amount of irritation into a more obvious blood clot in stool.

It is especially important to mention medication use when symptoms begin suddenly. Even over-the-counter pain relievers can matter, and prescription anticoagulants may make bleeding harder to stop. A clinician may need to weigh the bleeding risk against the reason the medication was prescribed.

Other factors can also play a role, including recent procedures, alcohol use, liver disease, or a history of ulcers. That is why a complete medication and health history is often part of the evaluation.

9. Other possible causes

Less common causes include injuries to the rectum, blood vessel problems, and complications from certain medical procedures. A change in bowel habits, severe constipation, or repeated irritation from diarrhea can also contribute to bleeding. In some cases, a blood clot in stool may be the visible result of a small tear or lesion that has already started to heal by the time it is noticed.

Because the list of possible causes is broad, the exact explanation depends on the pattern of bleeding and the rest of the symptoms. One episode may be minor, but recurrent bleeding is a different situation and usually deserves more attention.

What color blood suggests about the source

The color of the blood can help narrow down where it may be coming from:

• Bright red blood: Often from the anus, rectum, or lower colon
• Dark red or maroon blood: May come from higher in the colon or lower small intestine
• Black, tarry stool: Often suggests bleeding higher in the digestive tract

Blood clots in stool are often dark red or maroon because the blood has had time to collect before passing. When a blood clot in stool is mixed with black stool or a tar-like texture, the source may be farther up the digestive tract and should be checked promptly.

Color alone does not tell the whole story. Bright red bleeding can still be serious if it is heavy, repeated, or associated with dizziness. Likewise, dark stool can sometimes be caused by foods, supplements, or medications, so the rest of the clinical picture matters too.

Other signs to watch for

A blood clot in stool may happen on its own, or it may come with other symptoms that help identify the cause.

Watch for:

• Abdominal pain
• Rectal pain
• Diarrhea or constipation
• Fever
• Nausea or vomiting
• Weakness or dizziness
• Fatigue
• Unexplained weight loss
• Changes in bowel habits
• Feeling like you still need to pass stool after going
• Pale skin or shortness of breath
• Swelling or tenderness around the anus

These symptoms can help a doctor determine whether the bleeding is likely due to a minor or more serious condition. A single blood clot in stool may be less concerning than repeated bleeding, but symptom patterns matter just as much as appearance. The timing of the bleeding also matters: bleeding after a hard bowel movement suggests a different source than bleeding with fever and diarrhea.

Keeping track of what you ate, what medications you took, whether you had abdominal cramps, and how long the bleeding lasted can make the evaluation easier. Even small details can help point toward the right diagnosis.

When should you worry about blood clots in stool?

You should seek medical attention if you notice blood clots in stool, especially if:

• The bleeding happens more than once
• You pass a large amount of blood
• The stool is black or tarry
• You feel dizzy, faint, or weak
• You have severe abdominal pain
• You have a fever along with bloody diarrhea
• You are taking blood thinners
• You have a history of ulcers, colon polyps, inflammatory bowel disease, or colorectal cancer
• You are over age 45 and have new rectal bleeding
• You notice weight loss, fatigue, or a change in bowel habits

Get emergency care right away if:

• You have heavy rectal bleeding
• You pass large blood clots repeatedly
• You feel faint or short of breath
• You have chest pain
• You vomit blood
• Your stool is black and sticky
• You have signs of shock, such as rapid heartbeat, confusion, or sweating

Heavy bleeding can become serious quickly and should not be ignored. If you are unsure whether the blood clot in stool is an emergency, it is safer to get checked sooner rather than later. It is also worth remembering that people can lose a meaningful amount of blood before they feel dramatically ill, so waiting for symptoms to become severe is not a good plan.

If the bleeding is accompanied by severe weakness, trouble breathing, confusion, or a fast pulse, emergency care is the right choice. These are signs that the body may not be tolerating blood loss well.

How doctors evaluate blood clot in stool

If you see a blood clot in stool, a doctor may ask questions about:

• The color and amount of blood
• How often it happens
• Whether you have pain, diarrhea, or constipation
• Any recent illness or travel
• Medication use, including aspirin or blood thinners
• Family history of colon disease or cancer
• Recent changes in diet, bowel habits, or weight

They may also perform a physical exam and recommend tests such as:

• Stool tests
• Blood tests
• Rectal exam
• Colonoscopy
• Sigmoidoscopy
• Imaging studies if needed

The goal is to find the source of the bleeding and determine whether it is minor or serious. If the doctor suspects a lower bowel problem, they may also compare your symptoms with other causes of rectal bleeding and digestive tract inflammation. A blood count can show whether bleeding has already affected you, while stool testing may help identify infection or hidden blood.

In some situations, the evaluation happens quickly, especially if the bleeding is heavy or the patient is unstable. In other cases, the workup is more gradual and focuses on outpatient testing. The right approach depends on how much blood has been lost and what else is happening.

Can a blood clot in stool go away on its own?

Sometimes minor bleeding from hemorrhoids or a small fissure may improve on its own, especially if constipation is treated and bowel movements become easier. However, you should not assume bleeding is harmless without knowing the cause.

Even if the bleeding stops, recurring blood clots in stool should still be checked by a doctor. A blood clot in stool that disappears and then returns can still signal an ongoing issue. Some conditions bleed intermittently, which means the symptom may come and go before a clear diagnosis is made.

That is why it is best to think of symptom improvement as reassuring, not proof that everything is fine. If the bleeding was substantial or you have other warning signs, medical follow-up is still important.

What you can do while waiting to be seen

If the bleeding is small and you are otherwise feeling well, these steps may help:

• Drink plenty of water
• Avoid straining during bowel movements
• Eat more fiber if constipation is a problem
• Avoid NSAIDs such as ibuprofen unless your doctor says they are safe
• Keep track of how much blood you see and how often it happens
• Write down any stomach pain, diarrhea, fever, or dizziness

Do not delay care if the bleeding is heavy, persistent, or accompanied by concerning symptoms. Even a seemingly mild blood clot in stool deserves attention if it keeps happening. If you can, note whether the blood is bright red, dark red, or black, and whether it is on the tissue, in the bowl, or mixed into the stool. Those details may help guide the next step.

While waiting, avoid self-treating with random remedies or extra doses of pain medication. If a clinician has prescribed a blood thinner or other medicine that might affect bleeding, do not stop it on your own without medical advice.

How to prevent some causes of rectal bleeding

Not all causes of blood clot in stool can be prevented, but some are linked to bowel strain or irritation. Helpful habits include:

• Eating a fiber-rich diet
• Staying hydrated
• Exercising regularly
• Avoiding prolonged sitting on the toilet
• Treating constipation early
• Following medication instructions carefully
• Getting regular colon cancer screening as recommended

These steps may reduce the risk of hemorrhoids, fissures, and straining-related bleeding. They can also help keep bowel movements soft and easier to pass, which lowers pressure on the rectum and anus.

If you have a history of digestive symptoms, staying alert to changes in stool color, stool shape, and bowel habits can make it easier to catch a blood clot in stool early and get the right care. Prevention is not only about diet; it also includes knowing when to ask for medical advice before a small problem becomes a bigger one.

For people who already have constipation, a long-term bowel routine may be helpful. For people with recurrent diarrhea, controlling the underlying cause can reduce irritation and bleeding. And for people taking medications that raise bleeding risk, regular follow-up is often important.

The bottom line

A blood clot in stool can happen for several reasons, from hemorrhoids and anal fissures to diverticular bleeding, inflammatory bowel disease, infection, or more serious conditions like colon cancer or upper gastrointestinal bleeding. The color of the blood, the amount of bleeding, and any other symptoms can help point to the cause.

If the blood is repeated, heavy, dark, or comes with dizziness, pain, fever, or changes in bowel habits, you should get medical attention promptly. Even when the cause turns out to be minor, visible blood in stool should never be ignored if it keeps happening. When in doubt, a doctor can help determine whether a blood clot in stool is related to a simple rectal source or something that needs urgent treatment.

For more background on general warning signs, the U.S. National Library of Medicine offers a helpful overview of blood in stool. Knowing what to watch for can make it easier to act early and get the right care.