The short answer
Blood in the stool is common and is most often caused by hemorrhoids or small tears, not cancer. Because it can occasionally be an early sign of colorectal cancer, though, any blood in the stool is worth getting checked — especially if it keeps happening or comes with other changes.
Most blood in the stool comes from hemorrhoids or small tears, not cancer.
Because it can sometimes be an early sign of colorectal cancer, it should always be checked.
Blood with a change in bowel habits, weight loss, or tiredness is more worth checking.
Getting it checked early is exactly how many colorectal cancers are caught in time.
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The full explanation.
The simple version
Seeing blood is frightening, but the most common causes are harmless — hemorrhoids (swollen veins) and small tears called fissures. Still, because blood in the stool can occasionally be an early sign of colorectal cancer, it is one symptom that is always worth checking.
What usually causes it
Bright red blood on the toilet paper or in the bowl often comes from hemorrhoids or a small tear, especially with constipation or straining. Digestive upsets and some medicines can also play a role. These causes are common and treatable.
Why it is still worth checking
Colorectal cancer is one of the more common cancers, and it is highly treatable when found early. Blood in the stool — particularly when it keeps happening, is mixed into the stool, or comes with a change in bowel habits, unexplained weight loss, or tiredness — is a reason to get checked rather than wait.
When to see a doctor
See a doctor about any blood in the stool, and sooner if it keeps happening or comes with a change in bowel habits, weight loss, or tiredness. Simple tests can find the cause, and checking early is how many colorectal cancers are caught in time.
Words to know
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Common questions
▸Does blood in the stool mean cancer?
Usually not. It is most often caused by hemorrhoids or small tears. But because it can occasionally be an early sign of colorectal cancer, it should always be checked.
▸Bright red or dark — does the color matter?
It can offer clues, but any blood in the stool is worth checking regardless of color. A doctor can help work out the source.
▸What else can cause blood in the stool?
Hemorrhoids, small tears (fissures), constipation and straining, digestive upsets, and some medicines are common non-cancer causes.
▸When should I be more concerned?
Blood that keeps happening, is mixed into the stool, or comes with a change in bowel habits, unexplained weight loss, or tiredness is more worth prompt checking.
Questions to ask your doctor
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