Seeing blood in your poop can be frightening. It is natural to immediately wonder whether something is seriously wrong. The good news is that blood in the stool is not always a sign of a dangerous condition. Common problems such as hemorrhoids or a small anal tear can cause bleeding. However, blood in the stool should not simply be ignored, because it can sometimes point to a condition that needs medical treatment.

What Can Cause Blood in Poop?

There are many possible causes of rectal or gastrointestinal bleeding, ranging from minor problems to more serious illnesses.

Two of the most common causes are hemorrhoids and anal fissures. Hemorrhoids are swollen veins in or around the anus that can bleed, particularly after straining during a bowel movement. An anal fissure is a small tear in the tissue around the anus, often caused by passing a hard or large stool. Both can produce small amounts of bright red blood. The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) lists hemorrhoids and anal fissures among common causes of lower gastrointestinal bleeding.

Other possible causes include diverticular disease, inflammation of the colon, inflammatory bowel diseases such as Crohn’s disease or ulcerative colitis, stomach or intestinal ulcers, infections, polyps, and cancers of the digestive tract.

Because so many conditions can cause bleeding, the appearance of the blood and any accompanying symptoms can provide important clues.

What Does Bright Red Blood Usually Mean?

Bright red blood on toilet paper, on the outside of the stool, or in the toilet bowl often comes from somewhere near the end of the digestive tract, such as the rectum or anus.

For example, a person who has been constipated and strained to pass a hard stool may notice a small streak of bright red blood afterward. This may be caused by a hemorrhoid or anal fissure rather than a serious internal illness.

The NHS notes that a small amount of one-off rectal bleeding is not usually a serious problem and may sometimes resolve on its own.

However, repeatedly seeing bright red blood still deserves medical attention, particularly if there is no obvious explanation.

What About Dark Red or Black Poop?

Dark red, maroon, or black stool can be more concerning.

Black stool that is sticky or tar-like can indicate bleeding higher in the digestive system, such as in the stomach or upper intestine. Conditions such as stomach ulcers or gastritis can cause this type of bleeding.

Not every dark stool is caused by blood. Certain foods, iron supplements, and some medicines can change stool color. However, it can be difficult to tell the difference yourself. New black, tarry stool should therefore be medically assessed rather than assumed to be harmless.

When Should You Be Worried?

The amount of bleeding and the other symptoms occurring with it are important.

Seek urgent or emergency medical attention if you have:

• A large amount of blood or bleeding that will not stop
• Large blood clots
• Black, tarry stool
• Severe or worsening abdominal pain
• Dizziness, fainting, unusual weakness, or confusion
• A rapid heartbeat or difficulty breathing
• Pale, cold, or clammy skin

Heavy gastrointestinal bleeding can lead to significant blood loss and, in severe cases, shock.

What If There Is Only a Tiny Amount?

A tiny streak of bright red blood after constipation or straining is generally less alarming than heavy bleeding, particularly if it happens only once.

Still, “less alarming” does not mean “always safe.”

If the bleeding repeatedly comes back, continues for more than a short period, or occurs alongside other changes in your health, it is worth getting checked. Unexplained weight loss, persistent changes in bowel habits, ongoing abdominal discomfort, unusual tiredness, or weakness are particularly important symptoms to mention to a healthcare professional.

Repeated bleeding can also gradually lead to iron-deficiency anemia, even when the amount of blood lost at any one time seems small. Chronic gastrointestinal bleeding may cause symptoms such as tiredness, pale skin, and shortness of breath.

Does Blood in Poop Mean Cancer?

No. Blood in the stool does not automatically mean cancer.

Hemorrhoids, fissures, inflammation, ulcers, diverticular disease, and several other conditions can all cause bleeding. Nevertheless, cancers and precancerous polyps of the colon or rectum are among the possible causes, which is one reason unexplained or persistent bleeding should be investigated rather than self-diagnosed.

A doctor may ask about the color and amount of blood, your bowel habits, medications, age, family history, and other symptoms. Depending on the situation, testing might include blood tests, stool tests, a physical examination, or procedures such as endoscopy or colonoscopy.

The Bottom Line

Blood in your poop is not always a very bad thing. A small amount of bright red blood can come from relatively minor problems such as hemorrhoids or an anal fissure.

At the same time, blood in the stool is a symptom rather than a diagnosis. Persistent, unexplained, heavy, dark, or recurrent bleeding deserves medical attention.

If there is a large amount of blood, the bleeding will not stop, the stool is black and tarry, or you feel faint, dizzy, weak, confused, or severely unwell, seek urgent medical care.

For smaller amounts of blood that keep happening, arrange a medical evaluation rather than assuming hemorrhoids are responsible. Finding the cause is the safest way to determine whether treatment is needed.