Blood in stool: Common causes and when to see a doctor

It can be strange and a little scary to see streaks of blood in your poop, bright red water in the toilet or scarlet spots on your toilet paper.

The first thing to know is that bloody poop usually isn’t anything to worry about. Still, there’s a small chance that when you see red in your poop or after a bowel movement, it could be a sign of a medical condition. So in most cases, you’ll want to talk to a doctor or clinician about it.

But first, read on to learn about the causes of bloody stool and what to do next.

What blood in stool looks like (and what it means)

If you have blood in your stools, it can change the overall color of your poop, or show up as streaks or spots of blood in the toilet.

The color of blood in stool can be a sign of where the bleeding is coming from. That’s because blood changes color as it’s broken down by the digestive chemicals – the longer it spends in your digestive system, the darker it gets.

Here’s what poop color can mean:

Poop that’s nearly black could be caused by bleeding in the stomach or small intestines.
Poop that’s dark red or maroon could be caused by bleeding in your small intestines or in the upper part of your large intestines.
Bright red poop could be caused by bleeding from the rectum (part of the large intestines) or anus (where the poop comes out). Bright red poop can also be caused by a serious problem in your stomach or small intestines that’s causing you to bleed a lot over a short time.
Poop that’s normal color can sometimes have hidden blood (also called occult blood). This type of bleeding is found when you use a test like the fecal immunochemical test (FIT) and can be caused by bleeding anywhere in the digestive system.

However, poop color isn’t always a sign of where the bleeding starts. The color of your stool can be affected by many factors, including food and medicine (more on that below). It’s also possible to have bleeding in multiple locations at the same time.

Talking to your doctor is the best way to understand the meaning behind changes in poop color and to find out if you need treatment. So, make a doctor’s appointment if you see blood in your stool.

What blood after a bowel movement means

Bleeding in the digestive system can show up as bright red blood in the toilet water or on toilet paper after you wipe, and blood may briefly coat the stool when it lands in the water. It’s also possible for blood to dribble in the toilet after a bowel movement. As it spreads out, it can look like red food coloring in water. Blood after bowel movements is usually caused by bleeding in the rectum or anus, but it can also be caused by bleeding in your stomach or small intestines.

If it’s a small amount of blood in the toilet or on the tissue, it’s probably not a sign of a serious condition, but you’ll still want to talk to a doctor, especially if it’s happening frequently. If there’s a large amount of rectal bleeding over a short period of time, seek immediate emergency care.

5 common (and usually harmless) causes of bloody or dark stools

The most common reasons for red or dark poop and blood after a bowel movement are usually nothing to worry about. Still, it’s important to talk to a doctor to make sure.

1. Food and medications that affect poop color

Blood isn’t the only reason why poop can look reddish or black. Food and medications can affect poop color and texture. So if your poop doesn’t seem right, take a minute to think about what you’ve been eating.

Reddish stools can be caused by eating lots of beets, cranberries, red gelatin and tomato juice. Antibiotics like cefdinir can also cause red poop. But antibiotics can cause intestinal bleeding, so you shouldn’t ignore red poop if you’re on antibiotics.

Reasons for dark or blackish stools include foods like blueberries, chocolate and leafy greens. You may also have black poop after taking iron supplements or bismuth medications such as Pepto Bismol. Iron supplements can also cause constipation, which is a cause of rectal bleeding that’s covered later in the post.

2. Hemorrhoids

If you see blood after a bowel movement, a likely cause is hemorrhoids, which are swollen veins in the rectum or anus. Other common symptoms of hemorrhoids include an itchy bottom and discomfort when sitting.

Hemorrhoids develop when there’s increased pressure on the lower rectum. Possible causes for the extra pressure include chronic constipation, straining while pooping, spending long periods of time on the toilet (such as scrolling your phone or reading the newspaper), pregnancy, lifting heavy objects, having anal intercourse and being overweight.

Hemorrhoids usually aren’t anything to be concerned about. They sometimes go away on their own, but it’s a good idea to talk to a doctor about a treatment plan.

3. Constipation

Dealing with constipation can be a literal struggle. It can take a lot of straining and sometimes the stool that comes out is extremely hard or very large. And, unfortunately, all that straining and stretching can cause swelling and tears that lead to bleeding.

It’s not unusual to get constipated. But chronic constipation can be a sign of medical conditions. So if you consistently go less than three times a week, talk to your doctor.

4. Chronic diarrhea

When you have diarrhea, it can make your anus red and sore. But once you’ve gotten over the diarrhea, it usually won’t take long for your bottom to feel better.

If you have diarrhea for a long time, it can cause swelling or a tear near your anus. Chronic diarrhea can be a sign of other medical conditions. So if it lasts for more than four weeks, talk to your doctor to find out what’s causing it.

5. Anal fissures

An anal fissure is a tear in the skin around the anus. Reasons for anal fissures include straining to poop, very hard stools, chronic diarrhea and anal intercourse.

If you have an anal fissure that’s causing your rectal bleeding, you’ll likely feel pain or a burning sensation when you poop – and sometimes for hours afterwards. Anal fissures typically go away with home remedies. A doctor can help determine which treatments would be best for you.

5 causes of blood in stool that require medical attention

Some common causes of blood in stool and rectal bleeding need to be treated by a doctor. Not all are serious but can get worse without treatment.

1. Anal abscesses or fistulas

You have small glands in your anus that help you pass stool. But it’s possible for these glands to get infected and filled with pus – when this happens it’s called an anal abscess.

If you have an anal abscess, your body may create a fistula or a tunnel from the abscess to the skin around the anus. This is your body’s way of trying to drain the pus out of the abscess.

Abscesses and fistulas can cause rectal bleeding and discharge. And because they’re caused by infection, you may get a fever or chills. Anal abscesses and fistulas need to be treated by a doctor.

2. Peptic ulcers

Peptic ulcers are sores in the lining of the stomach or the upper part of the small intestines. Ulcers are usually caused by unbalanced digestive fluids, often from frequent use of nonsteroidal anti-inflammatory drugs (NSAIDs) like aspirin and ibuprofen.

Ulcers can also be caused by helicobacter pylori (H. pylori), which is a common stomach bacteria. Up to half of the people in the world may have it, but many don’t know it’s there because they don’t have any symptoms. If you have stomach ulcers, your doctor will likely test you for a H. pylori infection.

The most common symptoms are stomach pain, bloating, heartburn or nausea. Sometimes peptic ulcers can bleed, and the blood will show up in your poop. You might notice dark spots of blood in your stools, blackish stool or stools that look tarry. This is a more serious symptom of ulcers, and you should see a doctor.

3. Inflammatory bowel disease

If you have inflammatory bowel disease (IBD), it means your digestive tract tissues are chronically inflamed and swollen. When your body tries to digest food, you may experience symptoms such as diarrhea, stomach pain and the need to pass stools frequently.

Rectal bleeding can be a common symptom of IBD, depending on the severity of your condition. If you have a mild or moderate case, you’ll likely only have occasional bloody stools. But if you have a severe case, it’s possible to have 10 or more bloody bowel movements in a day. If you have the symptoms of IBD, make an appointment with a doctor. They can diagnose your condition and offer therapies to help with your symptoms.

4. Diverticulitis

Many people have small pouches called diverticula in the weakened parts of their large intestines. Usually, these pouches don’t cause any symptoms. However, if these pouches become inflamed, it could cause a condition called diverticulitis that includes complications like bleeding and infections. If you have symptoms like vomiting, abdominal pain and fever, you should make a doctor’s appointment.

5. Polyps

Polyps are clumps of abnormal tissue that can grow on the lining of your intestine. Polyps don’t usually cause any symptoms, so it’s unlikely that you’d know if you had them. But sometimes polyps can bleed or turn into cancer.

Blood in your poop can mean that you have larger polyps which can sometimes be a symptom of colorectal cancer. And your doctor may recommend you get a colonoscopy to make sure that you don’t have polyps that are cancerous or precancerous. But it’s rare that blood in stool means that you have cancer – research shows that cancer is the cause of bloody stools only 3.4% of the time.

When to see a doctor about blood in stool

If there’s one time when you see a little blood in the toilet or on the tissue only, it’s probably not a big deal – especially if you’re not experiencing other symptoms.

But it’s important to see a doctor if you frequently have bloody stools or see blood in the toilet. Chances are it’s nothing to be concerned about. But if it’s something more serious, like colorectal cancer, early diagnosis greatly increases the chance that treatment will be successful. A good place to start is with your primary care doctor. If necessary, they’ll refer you to another specialist for testing or treatment.

Depending on your symptoms, your doctor may recommend tests such as a colonoscopy to identify conditions that could cause rectal bleeding. They may also refer you to a digestive health specialist for testing and treatment.

When to go to urgent care or the emergency room for blood in stool

If you’re seeing a lot of blood or have severe abdominal pain or cramping, ask someone to drive you to urgent care. Very rarely, bleeding in the digestive system results in shock. Call 911, if you experience any of the following:

Weakness or fatigue
Rapid pulse
Rapid breathing
Dizziness

How your doctor diagnoses the cause of blood in stool

To diagnose the problem, your doctor will ask questions about the bleeding, how much it happens and when it occurs. So, it’s a good idea to keep track of times that you’ve had bleeding or bloody poop, and if you have other symptoms.

Talk to your doctor and stop worrying about bloody stools

It’s always a good idea to talk to your doctor if you’re experiencing rectal bleeding or bloody stools. While it’s unlikely that the rectal bleeding is being caused by something serious, they’ll have recommendations to help you heal more quickly, and help you get necessary treatment for more serious conditions like colorectal cancer, IBD or infections.

While it may feel embarrassing to talk about your symptoms, know that your doctor is used to having these conversations, and they want to know all the details. Because there are so many causes of bloody stools, the more they know, the better they can make a diagnosis and take the next steps in treatment.