Bright red blood in stool can be caused by hemorrhoids, an anal fissure, diverticula (small pouches in the colon), or abnormal blood vessels in the colon. In some cases, bright red blood in the stool may also be linked to Crohn’s disease, ulcerative colitis, or colorectal cancer.
Depending on the cause, bright red blood in the stool may be accompanied by other symptoms, such as painful bowel movements, abdominal discomfort, diarrhea, fever, weight loss, or a frequent and/or urgent need to have a bowel movement. It can also occur after certain medical exams like colonoscopy, or with rectal infections such as gonorrhea or syphilis that may cause discharge.
Medical evaluation by a colorectal specialist (proctologist/colorectal surgeon), gastroenterologist (GI doctor), or primary care provider helps confirm the cause and guide treatment. Care may range from increasing fiber and fluids and using warm sitz baths or hemorrhoid ointments to antibiotics, anti-inflammatory medicines, endoscopic procedures, or surgery, depending on the diagnosis.
What does bright red blood in stool mean?
The main causes of bright red blood in the stool are:
1. Hemorrhoids
Hemorrhoids are more common in people with constipation and can happen when veins around the anus become enlarged from straining during bowel movements.
Along with bright red blood in stool, hemorrhoids may cause discomfort, itching, and a swollen feeling around the anus.
How to treat: Simple steps, like increasing the amount of fiber in your diet and drinking more water, can help prevent bleeding from hemorrhoids. If there is pain, warm sitz baths for 15 minutes a day may be recommended. See sitz bath for hemorrhoids.
A doctor may also recommend hemorrhoid ointments to help relieve symptoms faster and, in some cases, surgery. For this reason, it is recommended to see a colorectal specialist or gastroenterologist for an evaluation.
2. Anal fissure
An anal fissure can also occur in people with constipation. It is a small tear in the skin around the anus that may bleed during a bowel movement and can cause pain and/or itching.
How to treat: To ease discomfort, it is recommended to take warm sitz baths, drink plenty of water throughout the day, and add more fiber to your diet to soften stool and reduce irritation during bowel movements.
It is also important to see a colorectal specialist or gastroenterologist, since ointments that support healing and help relieve pain may be recommended. In more severe cases, surgery may be needed to close the fissure.
3. Sexually transmitted infections
Some sexually transmitted infections (STIs), such as gonorrhea or syphilis, can affect the rectum in some cases and lead to symptoms like bright red blood in the stool, a frequent urge to have a bowel movement, and yellowish discharge from the anus, which may also contain blood.
How to treat: If an STI is suspected, it is recommended to see a gynecologist or a urologist. Treatment is usually done with antibiotics prescribed by a healthcare provider.
4. Medical exams
Some medical exams, such as a colonoscopy (a test used to check for changes in the intestine/colon), may cause bright red blood in the stool.
This can happen because small injuries to the intestinal wall may occur during the exam and bleed afterward, leading to blood in the stool. If polyps are removed during a colonoscopy, the risk of bleeding is higher. Read more about polyps in the colon.
How to treat: This kind of bleeding is usually normal and should not cause concern, as it typically stops within 48 hours. However, if the bleeding is very heavy or continues for more than two days, contact the doctor who performed the exam or visit the emergency room.
5. Diverticulitis
Diverticulitis occurs when diverticula, which are small pouches in the intestinal wall, become inflamed. Diverticulitis may also cause abdominal pain, nausea, vomiting, and even fever.
How to treat: Treatment should be managed by a gastroenterologist and is usually done with antibiotics and anti-inflammatory medications to treat a diverticulitis flare. However, since diverticula remain in the intestine, they can become inflamed again, so a specific diet may be recommended to help prevent another flare.
6. Abnormal blood vessels
Abnormal blood vessels in the colon are known as angiodysplasia. They can cause bleeding in the digestive tract, which may sometimes be noticed as bright red blood in the stool.
Bleeding from these vessels is usually not linked to other symptoms, but it can lead to anemia and, in some cases, make stools darker. Angiodysplasia is more common in people over 60 years old.
How to treat: Bleeding from abnormal blood vessels is usually not serious and often stops on its own. However, the bleeding may return later.
If angiodysplasia is suspected, it is recommended to see a colorectal specialist to confirm the diagnosis. In some cases, treatment using an endoscopy or colonoscopy may be recommended to block the abnormal vessels.
7. Crohn’s disease
Crohn’s disease is a chronic condition that causes significant inflammation in the intestine. It can cause symptoms such as stool with blood, ongoing diarrhea, low appetite, strong abdominal cramps, and weight loss.
How to treat: If Crohn’s disease is suspected, it is important to see a colorectal specialist or gastroenterologist. Once the diagnosis is confirmed, treatment typically involves medications that suppress the immune response and prevent future flare-ups.
8. Ulcerative colitis
Ulcerative colitis is an inflammatory bowel disease similar to Crohn’s disease. Depending on how severe it is, it can cause symptoms such as diarrhea with bright red blood in the stool, frequent and/or urgent need to have a bowel movement, abdominal pain, or weight loss.
How to treat: If ulcerative colitis is suspected, it is recommended to see a colorectal specialist or gastroenterologist. Treatment is usually done with medications to control inflammation in the intestine and, in some cases, surgery to remove the diseased part of the colon.
9. Colorectal cancer
Although less common, bright red blood in the stool can be a sign of colorectal cancer. Other symptoms may also be present, such as changes in how often you poop, tiredness, and weight loss.
How to treat: If cancer is suspected, it is very important to see a colorectal specialist or gastroenterologist for tests such as a colonoscopy or a CT scan, which can help confirm or rule out the diagnosis.