Why Do I Have Blood in My Stool?

It can be distressing to find blood in your stool, the causes of which range from relatively minor conditions like hemorrhoids to severe ones like colon cancer. In some cases, red stools may not even be caused by bleeding but by certain food or medications that you've eaten.

No matter the cause, it's important to see a healthcare provider if you find evidence of blood in your stools.

This article looks at some of the common and uncommon causes of hematochezia (blood in stools) and conditions that are sometimes mistaken for hematochezia. It also describes the various signs and symptoms that warrant an immediate medical investigation or emergency care.

Common Causes of Blood in Stool

The two things healthcare providers typically consider when there is blood in stool are hemorrhoids and anal fissures. This is especially true if the blood is bright red. Dark red or brownish-red blood generally suggests that the bleeding is higher up in the digestive tract.

Hemorrhoids and anal fissures involve bleeding in or near the anus that can collect on stools during a bowel movement.

Hemorrhoids

Hemorrhoids occur when blood vessels in the rectum or anus become swollen and inflamed. Bleeding from hemorrhoids can develop if you are constipated, and hardened stools scrape vulnerable tissues. It can also be the result of straining, which increase pressure within the swollen blood vessel.

In addition to bright red blood in stools, symptoms of hemorrhoids include:

• Anal itching
• A hard, tender lump near the anus
• Anal pain or ache, especially when you sit
• Rectal bleeding, often noticed when wiping with toilet paper
  

You can usually treat hemorrhoids at home by:

• Eating a high-fiber diet or using fiber supplements
• Taking a stool softener
• Drinking more water
• Avoiding straining when passing stool
• Taking over-the-counter (OTC) pain relievers like Tylenol (acetaminophen) or Advil (ibuprofen)
• Taking a sitz bath several times a day
• Using an OTC hemorrhoid cream, suppository, or ointment

Anal Fissures

An anal fissure is a tear in the lining of your anus. Common causes include passIng large stools, chronic diarrhea, straining, pregnancy, childbirth, and anal sex.

In addition to bright red blood in stools, symptoms of anal fissure mat include:

• Anal pain or itching
• Pain during and after bowel movements
• A visible cut or tear in the skin around your anus
• Rectal bleeding

You can often treat minor anal fissures at home by:

• Increasing fiber taking
• Drinking more water
• Taking stool softeners

Less Common Causes of Blood in Stool

More frequent causes of hematochezia generally involve bleeding higher up in the digestive tract. This is recognized by blood in the stool that is usually more maroon, brown, or blackish.

The color change results from the rapid oxidation of an iron-rich substance in the blood (called hemoglobin) as stools pass through the digestive tract. The higher the bleeding, the more extensive the oxidation and the darker the color. Some stools can even end up looking black and tarry.

There are five conditions for which this type of hematochezia might occur.

Colon Polyps

Colon polyps are growths in the colon (large intestine). Most are benign (non-cancerous) and some can turn malignant (cancerous) over time.

Colon polyps often cause no symptoms, particularly in the early stages. If symptoms do develop, they may include:

• Blood in stools
• Rectal bleeding, particularly after bowel movements
• Changes in bowel habit
  
• Fatigue (generally due to anemia caused by blood loss)
• Abdominal pain (generally due to bowel obstruction)
  

Because colon polyps tend to cause few symptoms, they are often only found during a routine colonoscopy. As a precaution, polyps may be removed during the colonoscopy with a procedure known as polypectomy.

Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) comes in two forms: ulcerative colitis and Crohn's disease. Both cause persistent inflammation in the large and small intestines.

Blood in stool is a characteristic symptom of IBD, the color or which can vary based on where in the digestive tract the bleeding is occurring.

In addition to blood in stool, other symptoms may include:

• Persistent, urgent diarrhea
• Abdominal pain and cramping
• Fever
• Constipation
• Loss of appetite
• Unintended weight loss
• Fatigue

Ulcerative colitis and Crohn's disease are typically treated with diet and medications called aminosalicylates, corticosteroids, immunosuppressants, and biologics that temper the underlying inflammation in different ways. In severe cases, surgery is needed.

Diverticular Bleeding

Diverticular disease is when small pouches develop in the lining of your large intestine. Although it's not terribly common, these pouches can sometimes bleed. If this happens, you may see a large amount of blood in your stool.

In addition to blood in stools, symptoms of diverticular disease can also include:

• Constipation
• Diarrhea
• Abdominal pain, which can be severe
• Bloating
• Rectal bleeding
  

The treatment depends on the severity of your symptoms. It may include a high-fiber diet and medications such as antibiotics and antispasmodics. Severe cases may require surgery to remove part of the colon, called a colectomy.

Upper Digestive Tract Bleeding

Digestive disease occurring higher up in the digestive tract (including the esophagus, stomach, and small intestine) can also cause blood in stools. Examples include peptic ulcers, esophagitis, esophageal tears, and tumors.

If you have upper digestive tract bleeding, you will typically experience black, tarry stools (referred to as melena).

Other symptoms of upper digestive tract bleeding include:

• Bloody vomit
• Vomit with a coffee ground appearance (due to the formation of blood clots)
• Abdominal cramps
• Dizziness
• Shortness of breath
• Fatigue and weakness
• Pallor (looking pale)
  

The treatment of severe upper digestive tract bleeding includes epinephrine (adrenaline) injections to rapidly shrink bleeding blood vessels and the cauterization (burning) of blood vessels with electricity or heat to stop the bleeding. Clips or bands may also be placed around vessels to cut off the blood flow.

Colon Cancer

Blood in the stool is often the first noticeable sign of colon cancer. This is why it is essential that any signs of blood in your stool be brought to the attention of your healthcare provider.

With colon cancer, stools will often be black and tarry. With that said, tumors located in the sigmoid colon (adjacent to the rectum) may cause dark red or maroon-colored stools, while those in the rectum may result in bright red stools.

Other symptoms of colon cancer include:

• Rectal bleeding
• Diarrhea or constipation (or alternating constipation and diarrhea)
• A feeling that your bowel doesn't completely empty
• Chronic abdominal pain or cramps
• Persistent fatigue
• Persistent gas or bloating
• Unexplained weight loss

The treatment depends on the stage of cancer. It may involve surgery, radiation, chemotherapy, or immunotherapy.

Other Causes of Stool Color Changes

Sometimes stool color can change when eating certain foods or taking certain supplements. You might confuse this with blood in the stools.

Harmless causes of stool color changes include:

• Beets
• Cranberries
• Tomatoes
• Blood sausage
• Black licorice
• Activated charcoal
• Food with red food coloring (such as strawberry gelatin)
• Bismuth found in Pepto-Bismol and Kaopectate that can cause black stools
• Iron supplements that can also cause black stools
  

What Should I Do if There's Blood in My Stool?

If you find blood in your stool or on your toilet paper or see any other evidence of rectal bleeding, call your healthcare provider and set up an appointment. Even if the cause is not serious, it is best to have that confirmed by a medical professional.

There are times, however, when you need emergency care when blood in stool is accompanied by symptoms of severe internal bleeding. If not treated immediately, a person may experience hypovolemic shock in which blood loss triggers a dangerous drop in blood pressure, leading to organ failure and death.

Symptoms of hypovolemic shock include:

• Dizziness or lightheadedness
  
• Rapid, weak pulse
• Rapid breathing
• Excessive sweating
• Blue lips (due to the loss of blood oxygen)
• Cold, clammy skin
• Confusion
• Anxiety or agitation
• Extreme weakness
• Pallor
• A feeling of impending doom
  
• Unconsciousness

Diagnosis

If you have blood in your stools, your healthcare provider will evaluate your symptoms and decide whether or not further investigation is needed.

Based on your symptoms, a review of your medical history, and a physical exam, your healthcare provider will choose which tests are most appropriate. Blood work may or may not be taken.

Direct or indirect imaging tests are commonly ordered to check for diverticular disease, colon polyps, tumors, and other causes of hematochezia. These include:

• Colonoscopy: A procedure used to directly view the colon with a flexible scope inserted into the rectum
• Sigmoidoscopy: A procedure used to directly view the sigmoid colon with a flexible or rigid scope inserted into the rectum
• Barium enema: An X-ray technique used to highlight the structure of the colon by delivering contrast fluid containing barium through the rectum
• Upper endoscopy: A procedure used to directly view the upper gastrointestinal (G) tract with a flexible scope inserted into the mouth
• Upper GI series: An X-ray technique, also called a barium swallow, used to highlight the structure of the upper GI tract

Summary

Blood in the stool (hematochezia) may be caused by a relatively minor condition or a potentially severe one. Hemorrhoids and anal fissures are two of the most common causes. Colon polyps, diverticular disease, inflammatory bowel disease, upper gastrointestinal bleeding, and colon cancer are other possible causes.

Red or black stools may also be caused by eating certain red-colored foods or taking iron supplements or Pepto-Bismol. Even so, it is important to see your healthcare provider if there is any evidence of blood in stools just to be safe.

A Word From Verywell

There is no such thing as a "safe" amount of blood in stools, particularly if the symptom is ongoing. You may assume that hemorrhoids are the cause, especially if you have a history of them, but persistent bleeding should be a red flag that something else may be going on.

Although colon cancer is a less likely cause of blood in stools, it is a symptom that commonly occurs when the disease is progressing. By ignoring this early symptom, you may rob yourself of the opportunity for an early diagnosis and treatment. And, in the end, the early diagnosis of cancer almost invariably affords better outcomes.