Few things are more frightening than seeing blood in the stool or on the paper. The good news is that most causes are benign — but there is one strict principle: blood should never be "automatically" attributed to haemorrhoids without assessment. The appearance of the blood gives clues to where it comes from, but only a doctor can confirm the cause.

What the appearance of the blood suggests

The look and location of the blood give some clues:

  • Bright red on the paper or on the surface of the stool: usually from the lower end (anus or rectum) — for example haemorrhoids or a fissure.
  • Dark red or mixed into the stool: may come from higher up in the colon.
  • Black, tarry stools (melaena): suggest bleeding from the upper digestive tract (stomach or duodenum) and need prompt assessment.

Note: these are clues, not a diagnosis. Two different causes can produce a similar picture.

The most common causes

  • Haemorrhoids: the most common cause. Bright red blood, usually painless, on the paper or in the bowl.
  • Anal fissure: a small tear in the lining of the anus. It causes bright red blood together with intense, sharp pain during or after a bowel movement, often after hard stools or constipation. It is very common and is often mistaken for "haemorrhoids".
  • Diverticula (diverticular disease): can cause painless, sometimes heavy bleeding.
  • Polyps and colon or rectal cancer: can bleed, often without pain — which is why bleeding should never be ignored.
  • Inflammatory bowel disease (e.g. ulcerative colitis): blood often with mucus, diarrhoea or abdominal pain.
  • Infections / gastroenteritis: transient, usually with diarrhoea.

When you should definitely be assessed

Even without emergency signs, bleeding needs assessment when:

  • It is new, persistent or recurrent.
  • It is accompanied by a change in bowel habits (persistent diarrhoea or constipation).
  • There is unexplained weight loss, fatigue or anaemia.
  • You are 45 or older or have a family history of colorectal cancer.

How it is investigated

Assessment starts with the history and clinical examination (digital rectal examination, anoscopy). Depending on the picture, age and risk factors, a colonoscopy may be needed — the test that checks the whole colon and can at the same time remove polyps or take a biopsy.

Related: Haemorrhoids · Anal fissure · Haemorrhoids: conservative or surgery? · Colon cancer · Preventive screening by age

Does blood on the paper definitely mean haemorrhoids?

No. It is the most common cause, but the same symptom can come from an anal fissure, diverticula, polyps or cancer. Medical assessment is needed to confirm.

How do I tell an anal fissure from haemorrhoids?

An anal fissure typically causes intense, sharp pain during or after a bowel movement together with bright red blood, often after hard stools. Haemorrhoids usually bleed painlessly. Only an examination confirms it reliably.

Should I worry if it was a little and stopped?

Even a small, transient episode is worth reporting to your doctor, especially if it recurs or if you are 45 or older or have a family history of colorectal cancer.

When is it an emergency?

With a large amount of blood, black tarry stools, dizziness, weakness or fainting, severe abdominal pain or fever. These need urgent medical help.

What test will I need?

Depending on the case: a clinical and proctological examination and, where indicated, a colonoscopy that checks the whole colon and can at the same time remove polyps or take a biopsy.