What Is Bloody Diarrhea?

This type of diarrhea can be caused by a number of health conditions, but there are ways to treat it and potentially prevent it from occurring.

Bloody diarrhea, which is bloody stool or rectal bleeding, can be a symptom of many medical conditions, such as hemorrhoids or inflammatory bowel disease (IBD). Fortunately, there are ways to treat and prevent bloody diarrhea, based on what's causing it. Here's what you need to know.

Bloody Diarrhea Symptoms

Depending on what's causing your bloody diarrhea, you might see blood:

  • Covering your poop
  • In the toilet bowl
  • Only on the toilet paper after you wipe

It might be bright red, dark red, or even a super dark, tar-like color. The longer the blood sits inside your digestive tract, the darker it'll be since it spends a more prolonged time interacting with digestive chemicals.

That means that, usually, bright red blood is less likely to indicate something serious because it usually starts low in your colon or rectum. However, seeing dark red blood in your diarrhea possibly means bleeding higher up in your digestive tract and needing to get checked out.

What Causes Bloody Diarrhea?

Bloody diarrhea can be the result of various medical conditions, such as anal fissures, infections, or ulcerations.

Anal Fissures

Anal fissures are minor cuts that happen at the anus. Anal fissures will likely bleed bright red, and you might see blood on the tissue or in the bowl, depending on how big the tear is or where it is.

Pain is the main noticeable difference between having bleeding hemorrhoids—which happen in the rectum—and an anal fissure. If pooping is painful and you see blood, you probably have an anal fissure.

Anal fissures can occur for several reasons. Usually, they're seen after chronic constipation or straining. You push so hard to get stool out that you end up tearing the skin at your anus. However, anal fissures also happen with chronic diarrhea and after childbirth.

Colorectal Cancer

If you're noticing dark brown or black stool or bright red blood on your tissue paper, it might be a symptom of colorectal cancer. Colorectal cancer can cause bloody diarrhea or stool when the tumors leak blood.

The whole purpose of tumors is to keep growing; to do so, they tap into your blood supply to suck up all the nutrition. When they're sitting inside your digestive tract, they can leak blood that you might see inside your toilet bowl. That blood might also make your poop look darker than usual.


Hemorrhoids—swollen blood vessels at the bottom of your rectum—are among the most common reasons you'll see blood in your stool. Many people with hemorrhoids notice a small amount of bright red blood on the stool, toilet, or toilet tissue.


Infections that may cause bloody stool include:

  • Gastrointestinal (GI) infections: The most common types of GI infections that cause rectal bleeding include infectious colitis or food poisoning.
  • Diverticulitis: Another type of infection occurs when diverticula, or bulges of tissue in the colon's wall, form and become inflamed. If a person has significant bleeding from diverticulitis, they'll sometimes need surgery to keep it from happening again.
  • Sexually transmitted infections (STIs): Gonorrhea, chlamydia, herpes, and syphilis are the most common STIs that cause rectal bleeding.

Some Inflammatory Conditions

Bloody diarrhea is often a symptom of inflammatory bowel disease (IBD), an umbrella term for disorders that cause chronic inflammation in your digestive tract. Bleeding is more familiar with ulcerative colitis (UC) than Crohn's disease, the two primary conditions under IBD.

Another type of inflammation that can cause rectal bleeding is proctitis, which is rectum inflammation. Proctitis may be part of IBD and can be caused by certain infections, such as STIs or food poisoning. In addition, radiation proctitis can occur after a person receives radiation therapy to treat cancer.


Peptic ulcers are sores that may occur on the stomach or small intestine linings. One complication of peptic ulcers is bleeding, caused by the ulcers breaking blood vessels. These ulcers can result in black or tar-like stools.

How Is It Diagnosed?

Healthcare providers will ask about a person's medical history and symptoms when diagnosing rectal bleeding. They may also complete a physical exam. Other testing might be necessary for diagnosis, including:

  • Anoscopy: Providers examine a person's anal canal and lower rectum using a rigid tube.
  • Diarrhea stool specimen culture: A stool specimen culture is necessary for determining what germs are responsible for infections causing bloody diarrhea.
  • Colonoscopy: Providers use this procedure to inspect the colon as a whole.
  • Sigmoidoscopy: This is a procedure where a provider may look at the rectum and the lower large intestine.

Treatments for Bloody Diarrhea

A major goal of treatment is to ensure that people do not become dehydrated if they have diarrhea. They may be told to drink diluted juices or drinks with electrolytes and eat bland foods like bananas, oatmeal, and toast.

Also, oral or intravenous rehydration therapy, which involves methods of replacing fluids, can be helpful in cases of diarrhea. Intravenous rehydration therapy is designated for severe cases of diarrhea.

Treatment for bloody diarrhea also varies based on what's causing it. For example, options can include stool softeners if a person has anal fissures or hemorrhoids and chemotherapy for individuals diagnosed with colorectal cancer.


Bloody diarrhea can be prevented in some cases. The following are ways to prevent the condition based on some causes:

  • Anal fissures: Avoiding hard bowel movements, increasing fiber in your diet, and using laxatives for hard stools
  • Hemorrhoids: Eating high-fiber foods, using stool softeners or fiber supplements, drinking enough fluids, avoiding straining during bowel movements, and avoiding sitting on the toilet for a long time
  • Infections: Practicing good hygiene and using condoms during oral, anal, and vaginal sex

Additionally, the mechanisms by which IBD occurs remain elusive. Although you cannot prevent IBD, there are some steps you can take to prevent or minimize flare-ups, such as:

  • Not smoking
  • Staying up-to-date on vaccinations
  • Screening for colorectal and cervical cancers
  • Consulting a healthcare provider about depression or anxiety
  • Checking your bone density, as IBD may increase your risk of developing osteoporosis

As for diverticulitis, the mechanisms by which the infection occurs remain unknown, so healthcare providers cannot prevent it.

Reducing Colorectal Cancer Risk

Steps that you can take to lower your risk of developing colorectal cancer include:

  • Being physically active
  • Decreasing alcohol consumption
  • Incorporating a healthy diet that decreases the number of animal fats and increases the number of fruits, vegetables, and whole grains
  • Maintaining a healthy body weight
  • Not smoking
  • Taking low-dose of aspirin, although research is limited regarding the association between aspirin and the risk of developing cancer


The primary complication of diarrhea is possible dehydration and electrolyte loss. When someone loses too much fluid and electrolytes, they can experience the following:

Living With Bloody Diarrhea

About 95% of rectal bleeding cases resolve, and the prognosis for general diarrhea is good. Staying hydrated during bouts of diarrhea, with or without blood, aids in a better prognosis.

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23 Sources
Health.com uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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