Blood in Stool: Common Causes for Pooping Blood and When It May Be an Emergency

Finding blood in your stool can be scary. Whether you notice blood just when you wipe or see bright red blood in your stool, it’s natural to want to get to the bottom of what could be causing it. Most cases of blood in your stool are from harmless causes of rectal bleeding, like hemorrhoids or anal fissures. But blood in your stool can also be a sign of something more serious, like colorectal cancer. 

It’s important that you don’t ignore your blood in your stool. Let’s take a closer look at what you should do if you see blood in your stool and when you should see a healthcare professional.

What are the symptoms of rectal bleeding?

If something causes bleeding from the lower parts of the colon, rectum, or anus, people typically notice symptoms like:

• Bright red blood when wiping 

• Red-tinged water in the toilet

• Bright red streaks on the outside of the stool

• Bright red blood mixed in with the stool

• Blood mixed with mucus and stool

• Bloody diarrhea 

• Tar-like black, smelly stool 

What if I’m pooping blood with no pain?

Many people who have rectal bleeding don’t feel any pain when they go to the bathroom. This is known as “painless rectal bleeding,” and it’s a common feature of many things that cause blood in stool, like hemorrhoids and colon polyps. 

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Blood in stool causes

Blood in your stool is caused by bleeding somewhere in the gastrointestinal (GI) tract. This blood can come from anywhere in the GI tract — from your mouth to your anus.

There may be some signs that help figure out where the blood is coming from along your GI tract and the possible cause.

There are many potential reasons for blood in your stool. The color of your stool — and the color of the blood itself — can be particularly helpful in finding the cause of the bleeding. Bright red blood in your stool, or hematochezia, is typically caused from bleeding in the lower part of your GI tract. Dark black or tar-like stools (melena) usually means the blood is coming from somewhere higher in the GI tract.

What causes bright red blood in your stool?

When you have bright red blood in your stool or blood when you wipe, it’s a sign that the bleeding is coming from the lower part of your GI tract. This can include bleeding from your lower colon, rectum, or anus. There are many possible causes of bright red blood in your stool. Here are the most common causes.

Anal fissure

An anal fissure is a tear in the anus related to stretching of the skin due to constipation or firm stool. Most people only notice blood when they wipe, while others notice blood in the toilet bowl or on their stool. 

Hemorrhoids 

Hemorrhoids are swollen blood vessels in the anus and are the most common cause of bright red blood in stool. Although everyone has hemorrhoids, when the blood vessels become enlarged or swollen, you can sometimes see bright red blood in your stool. 

Depending on the location of the hemorrhoids (internal versus external), there may be some associated pain. The most common cause of hemorrhoids is constipation or hard stools.

Colorectal polyps or cancer

Polyps are growths in the colon or rectum that, if left untreated, can turn into cancer. Both polyps and cancer can cause you to see blood in the stools. And this can frequently be the only symptom that you have. 

Colorectal cancer is unique because this type of cancer is preventable by removing the polyps before they turn to cancer. Recommendations for having a screening colonoscopy typically starts at age 45 for a person of average risk. 

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Angiodysplasia

Angiodysplasia refers to weakened blood vessels in the GI tract. These weak vessels are more likely to bleed than normal blood vessels. And this can be a cause of bright red blood in the stool.

Inflammatory bowel disease

Inflammatory bowel diseases (IBD) are medical conditions where your immune system attacks your intestines. This may result in fragile intestines that are more likely to bleed than the average person. Common examples of IBD are ulcerative colitis and Crohn’s disease. 

Diverticular disease

Diverticulosis is caused by outpouching of the wall of your colon. If these pouches become inflamed, you may suffer from diverticulitis. The walls of the pouches in those with diverticular disease are weaker than the normal colon wall. This makes them more likely to lead to bright red blood in the stool.

What causes dark black poop?

When blood comes from the upper GI tract, such as from the esophagus, stomach, or upper parts of the intestines, it gets partially digested. This can make the stool turn a dark black or tarry color and have a strong odor (melena). Let’s review some causes of upper GI bleeding.

Gastritis

If there’s too much acid in the stomach, it can become inflamed (gastritis). This inflamed tissue is more likely to bleed. That blood is partially digested as it travels through the GI tract and can result in dark or black stools. 

Peptic ulcer disease

If gastritis is left untreated, the inflamed stomach lining is likely to develop ulcers. These ulcers can be associated with pain and are more likely to bleed. In most cases of peptic ulcer disease, medications are used for treatment. But in severe cases, treatment might require surgery.

What causes bloody diarrhea?

Some people notice blood in their stool along with diarrhea. Let’s take a closer look at more common causes of bloody diarrhea.

Infectious gastroenteritis

If you develop bloody diarrhea all of a sudden, you may have gastroenteritis. Many viruses, parasites, and bacteria can lead to gastroenteritis, including salmonella and E. coli. If you have gastroenteritis, you may notice other symptoms like: 

• Fever

• Cramping

• Stomach pain

• Nausea

• Vomiting

Inflammatory bowel disease 

People who have IBD may experience bloody diarrhea during a flare of their illness. In some cases, bloody diarrhea may be the first symptom a person has of a new IBD illness. You may also notice:

• Abdominal pain

• Weight loss

• Bloating

• Fatigue 

Are there foods or drinks that cause blood in stool?

Some foods or supplements can change the color of your poop. Certain foods can make your stool turn red and look like blood when, in fact, it isn’t blood. This commonly happens with beets, but it can also happen with tomatoes or foods with red food coloring. 

On the other hand, some foods and drinks increase the chances of developing blood in your stool. 

Spicy foods

For some people, spicy food can cause diarrhea or irritate the stomach and lead to gastritis. This can worsen peptic ulcer disease or lead to hemorrhoids that cause blood in the stool. 

Alcohol

Similar to spicy foods, alcohol can also irritate the stomach lining and lead to gastritis and GI bleeding. The risk increases when you take NSAIDs (nonsteroidal anti-inflammatory medications), which also increase the risk of GI bleeding.

Gluten

Gluten is a protein that can be found in wheat, rye, barley, and other grains. If you have gluten intolerance or a wheat allergy, eating foods with gluten may cause you to have blood in your stools.

Can medications cause blood in stool?

Certain medications may increase the risk of GI bleeding and rectal bleeding. Be sure to talk with your healthcare professional about any GI bleeding. Medications that may increase the risk of bleeding include:

• Aspirin or other NSAIDs, like ibuprofen (Advil) or diclofenac

• Blood thinners, like apixaban (Eliquis), rivaroxaban (Xarelto), warfarin (Coumadin), and clopidogrel (Plavix)

• Corticosteroids, like prednisone

• Selective serotonin reuptake inhibitors (SSRIs) — which are used to treat depression and anxiety — like escitalopram (Lexapro), fluoxetine (Prozac), and sertraline (Zoloft)

A note about iron supplements

Iron supplements can change the color of your poop to a dark green or almost black color. This can look like dark, digested blood — but it’s not.

That said, iron supplements can sometimes cause constipation and worsen hemorrhoids or anal fissures. And this can cause bleeding. If you notice these changes, it’s a good idea to talk with a healthcare professional.

When to worry about blood in your stool

It’s natural to worry about finding blood in your stool or blood when you wipe. Most causes of bloody stool aren’t dangerous. But it’s a good idea to seek medical attention since blood can be a sign of colon cancer or other conditions, like ulcers or diverticulitis.

Make an appointment to be seen about blood in your stool sooner rather than later if you notice these symptoms:

• Change in bowel habits (such as new diarrhea or constipation)

• Blood in your stool, or blood when you wipe 

• Abdominal pain or an abdominal mass

• Nausea or vomiting

• Weight loss

• Fatigue or weakness

• Fever

• Bloody diarrhea 

Is rectal bleeding an emergency?

Sometimes rectal bleeding can be a sign of an emergency. It’s important to know when to seek emergency care and the signs to look out for, such as:

• Dizziness

• Heavy or ongoing bleeding

• Blood clots in the toilet

• Severe abdominal pain

• Vomiting blood

• Confusion

• Difficulty breathing

How do you diagnose blood in stool?

If you notice blood in your stool, connect with your healthcare professional to find and treat the cause. To make a diagnosis, they may ask you questions about your bleeding and review your other medical conditions and your medications. 

You may then have a physical exam, including a rectal exam. They may test your stool for blood, order lab tests, or do additional studies such as a colonoscopy. And they may refer you to a gastroenterologist for further evaluation.

Treatments for blood in stool

The treatment for blood in stool depends on the cause. This is why it’s important to be evaluated to get an accurate diagnosis. Common causes of bleeding, like hemorrhoids and anal fissures, often resolve with dietary changes and topical medications. Preventing constipation also helps. Other causes will need further evaluation and treatment.

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Written by:

Christina Palmer, MD

Christina Palmer, MD, is a board-certified family physician with a special interest in chronic care management, women’s health, mental health, and preventive care. She has over 10 years of experience in primary care research, innovation, and practice.

Edited by:

Karla Robinson, MD

Karla Robinson, MD, is a medical editor for GoodRx. She is a licensed, board-certified family physician with almost 20 years of experience in health through varied clinical, administrative, and educational roles.

Reviewed by:

Valerie Emuakhagbon, MD

Valerie Emuakhagbon, MD, is a board-certified colorectal surgeon. A native of Dallas, Texas, she completed the six-year BA/MD program at the University of Missouri-Kansas City.

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