Symptoms
Patient education · Reviewed by the treating clinician · Last reviewed January 2026
Gastrointestinal bleeding is blood loss from the digestive tract. Some of it is minor and settles on its own. Some of it is a genuine emergency that can become life-threatening within hours. The two can look surprisingly similar at the start, and neither patients nor doctors can reliably tell them apart without assessment.
Go to hospital now if you have any of these
- Vomiting blood, or material that looks like coffee grounds.
- Black, tarry, foul-smelling stools (melaena).
- A large amount of fresh red blood from the back passage.
- Fainting, near-fainting, cold clammy skin, a racing pulse, or breathlessness.
- Severe abdominal pain with bleeding, or bleeding with fever.
Call the hospital on (phone) before arriving so the team can prepare. If you cannot reach us, go straight to the nearest emergency department. Do not eat or drink, and do not take painkillers of the aspirin or ibuprofen type, which can worsen bleeding.
The four ways bleeding shows itself
| What you see | Medical term | Usually means |
|---|---|---|
| Vomiting bright red blood, or dark material like coffee grounds | Haematemesis | Bleeding from the oesophagus, stomach or duodenum — the upper gut |
| Black, tarry, sticky, foul-smelling stool | Melaena | Bleeding from the upper gut that has been partially digested |
| Fresh red blood in or on the stool | Haematochezia | Usually lower gut bleeding, though a brisk upper bleed can also present this way |
| No visible blood at all, found as anaemia on a blood test | Occult bleeding | Slow, low-volume blood loss, often from the colon or a stomach lesion |
Why the colour of the blood matters
Blood changes colour depending on how long it stays in the gut. Blood that has spent hours being digested becomes black; blood passed quickly stays red. This is a useful clue to where the bleeding is coming from.
What the colour does not tell you is how serious the bleed is. A small, slow bleed from a stomach ulcer can produce dramatic black stools, while a modest amount of fresh red blood can come from haemorrhoids. How you feel matters as much as what you see.
Signs that the bleeding is significant
These indicate real blood loss and possible shock. They mean emergency care, not a clinic appointment:
- Feeling faint or actually fainting, especially on standing up.
- Cold, clammy, pale or sweaty skin.
- A rapid or weak pulse, or a feeling of the heart racing.
- Shortness of breath, particularly on mild exertion.
- Chest pain, especially in someone with known heart disease.
- Confusion, drowsiness or unusual restlessness.
- Very little urine output.
Common causes — upper gut
- Peptic ulcer of the stomach or duodenum, often linked to H. pylori infection or to painkillers of the aspirin/ibuprofen type.
- Gastritis and duodenitis — inflammation of the stomach or duodenal lining.
- Oesophageal varices — enlarged veins in people with cirrhosis, which can bleed heavily and suddenly.
- Mallory-Weiss tear — a tear at the junction of the food pipe and stomach, typically after repeated vomiting.
- Stomach or oesophageal cancer — usually presenting with slower, chronic bleeding.
Common causes — lower gut
- Haemorrhoids and anal fissure — the commonest cause of fresh red bleeding, but a diagnosis of exclusion.
- Diverticular disease — small outpouchings in the colon that can bleed briskly.
- Colonic polyps and colorectal cancer.
- Inflammatory bowel disease — ulcerative colitis and Crohn’s disease.
- Angiodysplasia — small vascular malformations, more common in older patients.
- Post-procedure bleeding after polypectomy or biopsy.
What happens in hospital
- Assessment and stabilisation. Pulse, blood pressure, oxygen and blood tests including haemoglobin, coagulation and kidney function. Intravenous fluids and, if needed, blood transfusion.
- Medication review. Blood thinners and antiplatelet medicines are identified, and acid-suppressing treatment is often started.
- Endoscopy. Upper GI endoscopy is usually performed within 24 hours, and sooner if there is active bleeding or shock. It identifies the source and allows treatment in the same session.
- Endoscopic treatment. Depending on the cause, this may be injection, thermal coagulation, clips, band ligation for varices, or glue injection for gastric varices.
- Observation and prevention. Treatment to prevent re-bleeding, eradication of H. pylori if present, and a plan for the underlying condition.
Anaemia without visible bleeding — do not ignore it
Sometimes there is no blood to see. A routine blood test shows iron deficiency or anaemia, and there is no obvious explanation, particularly in men and in postmenopausal women. In that situation the gut should be examined even if you feel completely well. Slow, invisible blood loss from a colon polyp, an ulcer or an early cancer is a treatable cause, and it is much easier to treat when found early.
What you can do while waiting for help
- Do not eat or drink anything — you may need a procedure, and an empty stomach is required.
- Do not take aspirin, ibuprofen, diclofenac or similar painkillers.
- Lie down and keep warm if you feel faint, and raise your legs.
- Bring a list of all your medicines, especially blood thinners, and note when you last took them.
- Arrange for someone to come with you — you may need sedation or admission.
- Do not drive yourself to hospital.
Please remember
This article is general health information, not personal medical advice. It cannot account for your individual circumstances. Do not start, stop or change any medicine based on it. If you are worried about your symptoms, please book a consultation, and in an emergency seek care immediately.