If you see blood in your stool or toilet paper, you might be concerned. But while blood in stool can signal a serious problem, it isn't always the case.
Here's what you need to know about the possible causes of bloody stools and what you and your doctor should do if you discover a problem.
What Does Blood in Stool Look Like?
Blood in stool can appear in different colors depending on where it's coming from:
- Bright-red blood: You're bleeding in the lower part of your colon, rectum, or anus. The rectum connects your colon to your anus. The anus is the opening in your body through which your poop comes out.
- Dark-red or brown blood: You're bleeding in the higher part of your colon or in your small intestine.
- Black (aka melena): You're bleeding in your stomach, for instance from a stomach ulcer.
Sometimes, you won't see any bleeding in your stool, but it might be visible under a microscope. This is called occult bleeding.
Some foods can change the color of your poop. This doesn't mean there's blood in your stool; your stool might just take on a different color when you eat foods such as beets, tomatoes, or blackberries, or take supplements such as iron or some multivitamins.
You may be unaware of any bleeding and have no symptoms. On the other hand, you may also have abdominal pain, vomiting, weakness, difficulty breathing, diarrhea, palpitations, fainting, and weight loss depending on the cause, location, length, and severity of the bleeding.
When to Worry About Blood in Stool
Blood in your stool might be a sign of something mild, but sometimes it could be something serious. You should see a doctor if:
- You've had blood in your poop for over 3 weeks
- You have a lot of pain in your bottom
- You have pain or a lump in your stomach
- You have heavy bleeding
- Your poop has been softer, thinner, or longer than normal for 3 weeks
- You have no idea why you're bleeding (in other words, you're not bleeding because of constipation, diarrhea, or something you know about)
- You have bleeding along with fever, chills, fainting, weakness, or vomiting
Causes of Blood in Stool
Blood in stool means there's bleeding somewhere in your digestive tract. Sometimes, the amount of blood is so small that it can only be detected by a fecal occult test (which checks for hidden blood in stool). At other times, it may be visible on toilet tissue or in the toilet after a bowel movement.
Possible causes of blood in stool include:
Hemorrhoids. Also known as piles, hemorrhoids are the most common cause of bloody stool. These are swollen veins inside your bottom, which sometimes cause the skin in that area to break and bleed. It's caused by activities such as straining to poop (constipation) or heavy lifting. An itching bottom or pain can be a sign of hemorrhoids.
Anal fissure. This is a small cut or tear in the tissue lining the anus similar to the cracks that occur in chapped lips or a paper cut. Fissures are often caused by passing a large, hard stool and can be painful.
Inflammatory bowel disease (IBD). If you have bloody diarrhea and pain that goes on for weeks, along with weight loss, IBD might be the reason. This long-term condition inflames parts of your digestive tract. Experts aren’t sure exactly why that happens. There are two main kinds of IBD: ulcerative colitis and Crohn’s disease.
Ischemic colitis. This is when blood flow to your colon slows down or stops. The lack of oxygen causes damage to your intestine. The blockage can happen slowly over time, such as when cholesterol builds up in your arteries. Or it can happen all of a sudden from a blood clot or from a serious drop in your blood pressure. It can lead to bloody diarrhea and is usually accompanied by abdominal pain. The pain usually worsens when you eat.
Diverticular disease. Diverticula are small pouches that project from the colon wall. Usually, diverticula don't cause problems, but sometimes they can bleed or become infected.
Sexually transmitted infection (STI). STIs such as gonorrhea, chlamydia, syphilis, and herpes can cause inflammation and bleeding from your rear end. Bleeding can also be a result of damage from anal sex.
Colitis. This is inflammation of the colon.
Angiodysplasia. This is a condition in which fragile, abnormal blood vessels lead to bleeding.
Peptic ulcer. This is an open sore in the lining of the stomach or duodenum, the upper end of the small intestine. Many peptic ulcers are caused by infection with a common bacterium called Helicobacter pylori (H. pylori), which spreads via personal contact and contaminated food and water. Long-term use or high doses of anti-inflammatory drugs such as aspirin, ibuprofen, and naproxen can also cause ulcers.
Polyps or cancer. Polyps are benign growths that can grow, bleed, and become cancerous. Colorectal cancer (aka colon cancer) is the fourth most-common cancer in the U.S. and often causes bleeding that is not noticeable with the naked eye.
Esophageal problems. Varicose veins of the esophagus (food pipe) or tears in the esophagus can lead to severe blood loss.
Blood thinners. Drugs meant to prevent blood clots, such as warfarin or aspirin, can make your stool dark, but there is usually no pain associated with it.
Gastroenteritis. An infection in the stomach or intestines from a virus or bacteria (such as when you have food poisoning) can cause bloody diarrhea, along with nausea and vomiting. Bacterial infections that can cause bloody diarrhea include E. coli., salmonella, shigella, and campylobacter. An infection doesn’t usually last more than 2 weeks and won't come back after it gets better unless you catch the same infection again.
Endometriosis. A sign of endometriosis is bleeding from your bottom. Women and people with female anatomy get endometriosis when tissue similar to that in the lining of the womb grows in other places, such as your fallopian tubes and ovaries. The tissue becomes inflamed and bleeds when you have your period.
This is a sign of a problem in the gastrointestinal (GI) or digestive system. You'll either have overt (easy to see) or occult (not easy to see) signs of GI bleeding. It could happen in your upper or lower digestive system. “Upper” refers to body parts such as your esophagus and stomach. “Lower” refers to body parts such as your colon, rectum, and anus.
For overt GI bleeding, signs include:
- Vomiting blood, which might look red or brown and resemble coffee grounds
- Black, tarry stool
- Rectal bleeding, usually in or with your stool
For occult GI bleeding, signs include:
- Dizziness or fainting
- Difficulty breathing
- Chest pain
- Stomach pain
Some reasons for upper GI bleeding are peptic ulcers (the most common reason), enlarged veins in the esophagus, or a tear in the esophagus, called a Mallory-Weiss tear.
Though both parts of the GI tract could bring on blood in your stool, rectal bleeding often refers to bleeding from the lower GI tract. Common reasons are hemorrhoids, anal fissures, and constipation. Less common reasons are cancer, diverticulosis, IBD, and colitis.
Blood when wiping but not in stool
If you see bright-red blood on your toilet paper when you wipe, but there is none in your stool, this is probably due to hemorrhoids or an anal fissure. This is not serious and can be treated at home by applying a hemorrhoid cream, eating a high-fiber meal, and taking a warm bath.
Causes of Blood in Stool in Children
Many of the causes of blood in children's stool are the same as for adults, but some differ. Here are the most common for kids:
Constipation. This is the most likely cause of blood in stool for children. Constipation can lead to anal fissures, resulting in bleeding. Hemorrhoids are not very common in children.
Ulcers. These are sores on the lining of the digestive tract, caused by infection from the H. pylori bacteria. Your child will have sticky black bowel movements, along with chest pain and burping.
Food allergies. Proteins in breast milk or formula can cause babies to develop colitis, which refers to inflammation of the large intestine. These may come from proteins added to infant formula (such as cow's milk and soy) or from foods and drinks the mother consumes, which are transmitted to the breast-feeding baby, such as cow's milk, nuts, wheat, fish, and eggs.
Infectious diarrhea. This comes from a virus, bacteria, or parasite and is spread via person-to-person contact or by consuming contaminated food and water. It may manifest with the presence of blood in your child's stool.
Meckel’s diverticulum. A pouch of tissue extends out from the wall of the intestine, a remnant from when your child's digestive system was developing in the womb. Some of the tissue may be stomach tissue which makes acid, leading to symptoms such as painless rectal bleeding. About half of the cases are in young children, but it doesn't always cause any symptoms. You can correct this condition with surgery to remove the tissue.
Inflammatory bowel disease (IBD). The two main types of IBD -- ulcerative colitis and Crohn's disease -- can cause blood in stool.
Blood in Stool Diagnosis
It is important to have a doctor evaluate the blood in your stool. Any details you can give about the bleeding will help your doctor locate the site of bleeding. For example, a black, tarry stool is likely an ulcer or other problem in the upper part of the digestive tract. Bright-red blood or maroon-colored stools usually indicate a problem in the lower part of the digestive tract, such as hemorrhoids or diverticulitis.
After getting a medical history and doing a physical (rectal) exam, your doctor may order tests to determine the cause of bleeding. Tests may include:
Nasogastric lavage. This test may tell your doctor whether bleeding is in the upper or lower digestive tract. Your stomach contents are removed through a tube inserted into the stomach through the nose. If your stomach doesn't contain evidence of blood, the bleeding may have stopped or is more likely in the lower digestive tract.
Esophagogastroduodenoscopy (EGD). This procedure, also called an endoscopy, involves inserting an endoscope, a flexible tube with a small camera on the end, through your mouth and down your esophagus (food pipe) to the stomach and duodenum. The doctor uses this to look for the source of bleeding. Endoscopy can also be used to collect small tissue samples (called a biopsy) for examination under a microscope.
Colonoscopy. This is similar to an EGD except the scope is inserted through your rectum to view the colon. As with an EGD, a colonoscopy can be used to collect tissue samples for a biopsy.
Enteroscopy. This procedure, similar to the EGD and colonoscopy, examines your small intestine. In some cases, this involves swallowing a capsule with a tiny camera inside that transmits images to a video monitor as it passes through the digestive tract. The enteroscopy can capture a part of the body that is not reachable by the endoscopy.
Barium X-ray. This uses a contrast material called barium to make the digestive tract show up on an X-ray. The barium may either be swallowed or inserted into the rectum.
Radionuclide scanning. Small amounts of radioactive material are injected into your vein, and then a special camera is used to see images of blood flow in the digestive tract to detect where bleeding is happening.
Angiography. A special dye is injected into a vein to make blood vessels visible on an X-ray or CT scan. The procedure detects bleeding as dye leaks out of blood vessels at the bleeding site.
Laparotomy. The doctor opens and examines the abdomen via surgery. This may be necessary if other tests fail to find the cause of bleeding.
Other tests include:
Anoscopy. The doctor examines your anal canal using an anoscope, a small hollow tube with a magnifier.
Proctoscopy. This is a test that involves looking at your rectum and anus with the help of a small lighted tube called a proctoscope. It's also called a rigid sigmoidoscopy.
Flexible sigmoidoscopy. The doctor looks at your lower colon using a thin, flexible tube called a sigmoidoscope.
Rectal culture swab. A bacterial culture taken from your bottom is sent to the lab to identify infections.
Stool test. This lab test looks for clotting problems, anemia, and H. pylori infection in your stool.
Imaging test. A CT scan of your stomach checks for any problems there.
Treatment for Blood in Stool
Often, rectal bleeding will stop on its own if it's due to something like constipation, and you won't need further treatment. However, for more serious matters, treatment will depend on the cause of the bleeding.
It may include medications such as antibiotics to treat H. pylori, ones to suppress acid in your stomach, or anti-inflammatory drugs to treat colitis. You may need surgery to remove polyps or the parts of the colon damaged by cancer, diverticulitis, or IBD.
For less serious cases of rectal bleeding, you can do simple things at home to help yourself. These include:
- Eating a high-fiber diet to relieve constipation, which can worsen hemorrhoids and anal fissures
- Taking a sitz bath, which means sitting in warm water to relieve fissures and hemorrhoids
- Using an over-the-counter hemorrhoid cream to soothe pain
- Exercising to stimulate bowel movement
If you have a lot of bleeding, a doctor will use one of several techniques to stop it. Often, they use an endoscopy to inject chemicals into the site of bleeding, treat it with an electric current or laser, or apply a band or clip to close the bleeding vessel. If the endoscopy does not control bleeding, the doctor may use angiography to inject medicine into the blood vessels.
Blood in your stool could mean you have hemorrhoids, constipation, or something more serious like inflammatory bowel disease or cancer. The blood might clear up on its own, but if it lasts over 3 weeks or the bleeding is heavy, you should see your doctor to get some answers.
Blood in Stool FAQs
When should I be worried about blood in my stool?
If you have heavy bleeding, pain, and other symptoms such as fever, chills, or dizziness, you should seek medical attention right away.
Is blood in stool usually serious?
Most of the time, no. The most common reasons for blood in stool are hemorrhoids and anal fissures from constipation, which can be easily treated. But blood in stool can be a sign of something more serious, such as colorectal cancer.