At a glance
Rectal bleeding is common. It is also frightening. The combination of seeing blood in an intimate area and not knowing what it means creates significant anxiety.
The good news: most rectal bleeding is caused by benign conditions — hemorrhoids, fissures, and minor tears. The important part: it should always be checked at least once to confirm the cause.
This guide helps you understand what different patterns of rectal bleeding may mean, when to seek routine assessment, and when to seek urgent care.
Common benign causes
Hemorrhoids
The most common cause of rectal bleeding. Typically bright red blood on the toilet paper, on the stool surface, or dripping into the bowl. Usually painless (internal hemorrhoids) or associated with a lump (external hemorrhoids).
Anal fissure
A small tear in the anal lining. Causes bright red blood, usually with sharp pain during bowel movements. Often triggered by hard stools or constipation.
Minor tears from straining
Even without a chronic fissure, hard stools and straining can cause minor tears that bleed briefly. This typically resolves once the stool softens.
Patterns that need assessment
While most rectal bleeding is benign, certain patterns should be assessed by a clinician:
- Persistent bleeding that continues over several weeks
- Recurrent episodes — bleeding that keeps coming back
- Bleeding with a change in bowel habits — new constipation, diarrhoea, or altered frequency
- Bleeding with mucus — may indicate inflammation in the bowel
- Bleeding with unexplained weight loss
- Bleeding in someone over 40 who has not been investigated before
- Any bleeding that does not have an obvious explanation
None of these patterns necessarily indicate something serious. They indicate that investigation is worthwhile to confirm the cause and provide appropriate management.
Patterns that need urgent care
Seek immediate medical attention for:
- Heavy bleeding that fills the toilet bowl, soaks through pads, or will not stop
- Bleeding with dizziness, lightheadedness, or fainting — may indicate significant blood loss
- Dark red, maroon, or black stool — may indicate bleeding from higher in the bowel
- Bleeding with severe abdominal pain
- Bleeding with fever
These presentations need urgent assessment, usually in A&E.
Understanding the colour
The colour of the blood provides useful information:
- Bright red: typically from the anus or very low rectum — hemorrhoids, fissures, minor tears. Most common and usually benign.
- Dark red or maroon: may indicate bleeding from higher in the colon. Needs investigation.
- Black, tarry stool (melaena): may indicate bleeding from the upper digestive tract (stomach or small bowel). Needs urgent investigation.
The role of age
While colorectal conditions like hemorrhoids and fissures affect all ages, the threshold for investigation changes with age:
- Under 40: benign causes are overwhelmingly likely. Investigation is still appropriate for persistent or concerning symptoms.
- Over 40: the very small risk of more serious causes increases with age. Most guidelines recommend a lower threshold for investigation, particularly colonoscopy.
- Over 50 or family history: screening and prompt investigation of any bleeding are particularly important.
What to do
For minor, one-off bleeding
- Note what happened — was there straining? Hard stool?
- Monitor for recurrence
- Address constipation if present
- Mention it to your GP at your next routine appointment
For recurring bleeding
- See your GP for assessment
- They may examine the area and refer for further investigation if needed
- Do not assume it is “just hemorrhoids” without having it confirmed
For heavy or concerning bleeding
- Seek urgent medical attention
- Do not delay — significant bleeding needs assessment regardless of the likely cause
The honest message
Rectal bleeding is almost always caused by something common and treatable. But “almost always” is not “always.” The purpose of getting it checked is not to look for something terrible — it is to confirm the benign cause and get appropriate treatment. One appointment can provide that reassurance.