Not all changes in bowel movements are cause for concern, but noticing blood in your stool or the toilet bowl, or on toilet paper, can sometimes be a sign of an underlying condition.
Possible causes of bloody stool include anal fissures, inflammatory bowel disease (IBD), ulcers, or colorectal cancer.
Understanding the possible root of your bloody stool and any associated symptoms can be helpful when navigating how to improve the bleeding.
Still, speaking with a health care provider is highly recommended if you’re noticing blood in your stool, especially if you’re experiencing any additional or severe symptoms like anal discharge, vomiting, or severe abdominal pain.
Causes of Blood in Stool
There are several possible causes of blood in stool.
When speaking with your health care provider, it can be helpful to identify the color of the blood in your stool, as this can clue your provider into where the bleeding is occurring.
Generally, bright red blood in your stool signals that the bleeding is coming from your colon or rectum.
On the other hand, dark red blood can indicate bleeding higher in the colon or small bowel.
Dark red brown or tar-like stool is potentially a sign of bleeding in the stomach.
Anal fissures are tears in the anal canal, which holds the muscles responsible for controlling your bowel movements.
In addition to causing anal spasms and discomfort, anal fissures can cause:
- Pain that gets worse during bowel movements
- Bright red bleeding or blood in stool
Anal fissures can occur after passing hard stool or prolonged diarrhea.
In many cases, certain lifestyle changes, like drinking plenty of water and eating an adequate amount of fiber, can help heal anal fissures.
Hemorrhoids occur when the veins and blood vessels in and around the anus and rectum become swollen and irritated.
Hemorrhoids are very common and can be caused by several factors including pregnancy, straining during bowel movements, age, and having chronic constipation or diarrhea.
Symptoms of hemorrhoids include:
- Pain and irritation around the anus
- Bright red blood in stool
- Swelling or a hard lump around the anus
Treatment will vary depending on your health, age, and the severity of your hemorrhoids.
To help reduce your pain and symptoms, your provider may recommend warm water sitz baths, ice packs, or hemorrhoid creams.
In more severe cases, surgery may be needed.
Anal abscesses or fistulas
If the small glands inside your anus become infected, that can lead to an anal abscess or fistula.
An abscess describes a gland that has accumulated pus, while a fistula is a tiny tunnel that connects the abscess to the skin around the anus.
Inflammatory bowel disease (IBD), tuberculosis, or radiation treatments can cause anal abscesses or fistulas. Unfortunately, surgery is almost always necessary to treat a fistula.
Diverticulosis and diverticulitis
Diverticulosis and diverticulitis are two conditions that occur in the large intestine.
Diverticulosis refers to the presence of small bulges or pockets (known as “diverticula”) in the colon; in most cases, they don’t cause any symptoms.
However, diverticulosis can lead to diverticulitis, which is inflammation and infection in one or more diverticula.
Symptoms of diverticulitis include:
- Pain, tenderness, or sensitivity in the lower left side of the abdomen
- Nausea or vomiting
- Abdominal cramps
- Diarrhea (less common)
- Blood in stool
Diverticulosis doesn’t require treatment but several measures can help treat diverticulitis, depending on the severity of your condition.
If diagnosed, antibiotics, over-the-counter (OTC) medications, or surgery may be recommended by your provider.
Inflammatory bowel disease (IBD)
Inflammatory bowel disease (IBD) refers to the inflammation within the digestive tract and includes Crohn’s disease and ulcerative colitis (UC).
Common IBD symptoms include:
- Blood or mucus in stool (often diarrhea)
- Painful bowel movements
- Abdominal pain
- Constipation (more common with UC)
- Nausea and vomiting (more common in Crohn’s)
Unfortunately, there is no cure for IBD, but there are medications that can help with symptom management.
These include anti-inflammatory medications, corticosteroids, antibiotics, biologics, and immunomodulators.
A peptic ulcer is a sore in the lining of your stomach or duodenum, which is the first part of your small intestine.
An ulcer can occur as a result of infection, long-term use of nonsteroidal anti-inflammatory medicines (NSAIDs), or when the acids that work to digest food damage the stomach or intestine walls.
In addition to causing burning stomach pain, ulcers can bleed, causing dark red or black stools.
There are several medications that can be used to treat a peptic ulcer.
Colon polyps are growths that can be flat, slightly raised, or on a stalk and that appear on the inner lining of the large intestine or colon.
They grow as a result of genetic changes in the cells of the colon.
Most polyps don’t cause symptoms early on and are detected via different screening procedures, including colonoscopies, sigmoidoscopies, or CT scans.
When symptoms do occur, they can include:
- Blood in stool
- Anemia or weight loss
- Change in normal bowel movement patterns
- Abdominal pain (rare)
If a polyp is found, your provider will remove it for testing to determine what type of polyp it is, which will in turn determine your treatment plan.
When left untreated, colon polyps can lead to cancer.
Sexually transmitted infections (STIs)
Some sexually transmitted infections (STIs), including syphilis, chlamydia, herpes simplex virus, and gonorrhea can cause rectal bleeding.
If you’re sexually active, experiencing rectal bleeding, and have not had a recent STI screening, talk to your provider about which testing options are right for you.
In rare cases, bloody stool can be a sign of colorectal cancer.
Additional symptoms, if present, can also include:
- Rectal pain or pressure
- Bright red, maroon, or black blood in stool, underwear, or toilet paper
- Mental confusion
- Feeling lightheaded or dizzy
If you’re experiencing any of the above symptoms, it’s important to reach out to your health care provider as soon as possible.
Speaking with a health care provider is the best way to diagnose the cause of your rectal bleeding.
To start, your provider may ask you questions about your symptoms and health history.
Once your provider has a better understanding of what you’re experiencing, they may perform a physical exam of your rectum and anus.
Additional testing may include:
- A colonoscopy
- A sigmoidoscopy
- A fecal occult blood test
Treatment will vary depending on the cause of your bloody stool and/or rectal bleeding.
This is why it’s important to reach out to a medical provider for more information if you’re experiencing symptoms.
Adults vs. Children
Blood in stool in adults may be a result of one of the causes we’ve gone over.
In children, the most common causes of blood in stool are:
- Anal fissures
- Strep skin infection
- Bacterial diarrhea
- Cow’s milk colitis
If your child has a small amount of blood in their stool but no other symptoms, you should contact their pediatrician within 24 hours.
Additional symptoms that warrant immediate medical attention in children are:
- Bloody diarrhea
- Pink or tea-colored urine
- Stomach pain
- Skin bruises not caused by injury
- If your child is less than 12 weeks old
When To See a Doctor
Though the causes of blood in stool range from mild to severe, it’s a good idea to reach out to your provider if you’re noticing bloody stool, especially over several days.
Symptoms in adults that warrant immediate medical attention include:
- Experiencing a sudden drop in blood pressure
- Having a fast heart rate
- Not being able to urinate
- Slipping into unconsciousness
How K Health Can Help
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K Health articles are all written and reviewed by MDs, PhDs, NPs, or PharmDs and are for informational purposes only. This information does not constitute and should not be relied on for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.
K Health has strict sourcing guidelines and relies on peer-reviewed studies, academic research institutions, and medical associations. We avoid using tertiary references.
Anal Cancer. (2021).
Anal Fissures. (2021).
Inflammatory Bowel Disease. (2021).
Peptic Ulcer. (2016).
Sexually transmitted proctitis. (2006).
Symptoms & Causes of GI Bleeding. (2016).