What causes rectal bleeding?

There are many different reasons why you might experience rectal bleeding. The causes of rectal bleeding can vary from common and mild conditions to more severe and rare conditions that need immediate medical treatment.

Causes of rectal bleeding can include:

  • Hemorrhoids: The most common cause of rectal bleeding, hemorrhoids are swollen veins in the rectum (internal hemorrhoids) or the anus (external hemorrhoids). You can develop hemorrhoids for many reasons, including chronic constipation, straining during bowel movements, pregnancy, lifting heavy objects, having anal intercourse and having a higher body weight (obesity). Hemorrhoids aren’t a medical emergency and the blood you may see on your toilet paper or in the toilet bowel isn’t something to be majorly concerned about.
  • Anal fissure: Sometimes confused for a hemorrhoid, an anal fissure is a split or tear in the skin around the anus. This happens when you have very hard stool that’s difficult to pass. The extra pressure of the bowel movement causes the skin to split open. An anal fissure can cause you to see blood when you go to the bathroom, as well as feel burning during bowel movements. Anal fissures usually go away on their own over time.
  • Anal abscess or fistula: There are actually small glands inside your anus that are meant to help you pass stool. These glands can become infected causing abscesses or fistulas. When the gland inside the anus builds up puss, causing a blockage, it’s an abscess. An anal fistula is a tiny tunnel that connects the abscess to the skin around the anus. These conditions can be caused by inflammatory bowel disease, tuberculosis or radiation treatments.
  • Diverticulosis/Diverticulitis: These conditions happen when small pouches — called diverticuli — develop in weakened sections of your intestine. These diverticuli can protrude through the walls of your bowels, causing bleeding and infections. When these pouches get infected, they can cause symptoms like abdominal pain, fever and a sudden change in bowel habits.
  • Inflammatory bowel disease (IBD): Inflammatory bowel disease (IBD) is swelling of the small or large intestine. There are two types of IBD — crohn's disease and colitis. Crohn’s disease is a condition where you develop patches of swelling in the digestive tract. In colitis, the swelling is mainly in the large bowel. People with IBD might experience fever, diarrhea, abdominal pain and cramping, intestinal blockages, and rectal bleeding.
  • Ulcers: When the amount of digestive fluids in your intestines is out of balance, it can damage the lining of your digestive tract and cause ulcers. These can bleed, causing you to have black stool that’s sometimes tar-like in appearance.
  • Large polyps: A polyp can look like a mushroom that’s growing out of the side of your bowel. Large polyps can bleed, causing you to experience rectal bleeding. In some cases, polyps can turn into cancer if left untreated. It’s important to have rectal bleeding related to polyps checked because it could be a sign of colorectal cancer.

Are there any foods that can change the color of my stool in a similar way to rectal bleeding?

There are certain foods that can make your poop an unusual color. You can have green, yellow and even black stool. This can happen for a variety of reasons – having too much bile during digestion, having a medical condition like inflammatory bowel disease or celiac disease, being on antibiotics, or even just eating foods with strong color pigments.

Often, blood can make your stool look very dark and almost black. Foods like black licorice, beets, dark berries (blueberries and blackberries) and red gelatin can all make your poop look very dark. This can easily be confused for blood in your stool. If you notice very dark poop during a bowel movement, think back to what you ate recently. There’s a chance that what you ate could be the cause for the usually dark stool.

Can straining too hard for a bowel movement cause rectal bleeding?

Straining too hard during a bowel movement can cause rectal bleeding. This is often related to constipation. When you strain, you can cause conditions like hemorrhoids or anal fissures. Very hard stool can actually cause the skin around your anus to tear, causing you to see blood. Treating constipation can help prevent this from happening.

Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy