symptoms of bowel cancer
Bowel cancer (also called colorectal or colon cancer) can cause several bowel and general symptoms, but these can also be due to many less serious conditions.
⚠️ Important first points
- Having one or more of these symptoms does not automatically mean bowel cancer, but you should not ignore ongoing or unexplained changes.
- See a doctor urgently or seek emergency care if you notice heavy bleeding, severe tummy pain, repeated vomiting, or signs of severe anaemia (extreme tiredness, dizziness, shortness of breath).
Main bowel symptoms to watch for
These are the most commonly described symptoms of bowel cancer in major medical sources.
- Change in bowel habit that lasts more than a few weeks:
- New diarrhoea or constipation, or going more or less often than is normal for you.
* Stools becoming narrower, thinner, or having a different consistency than usual.
- Blood in your poo or from your bottom (rectal bleeding) :
- Bright red blood on the paper, in the toilet, or mixed with the stool.
* Very dark or black stools, which can indicate digested blood.
- Feeling you haven’t emptied your bowel properly :
- A sensation of needing to poo again right after going, or constantly feeling like you need to pass a stool.
- Persistent tummy (abdominal) discomfort :
- Cramping, bloating, or pain in the abdomen that doesn’t settle.
* Pain in the back passage or anal area.
- Lump, swelling, or blockage signs :
- A noticeable lump in the tummy, or in the anus/rectum.
* Severe constipation with bloating, tummy pain, and vomiting can suggest a bowel obstruction, which is an emergency.
Whole‑body (general) symptoms
As bowel cancer progresses, it can cause broader symptoms that reflect blood loss, weight changes, or systemic illness.
- Unintentional weight loss – losing weight without trying through diet or exercise.
- Tiredness, weakness, or shortness of breath – often due to anaemia from slow, chronic blood loss in the bowel.
- Pale complexion and dizziness – also signs of anaemia.
- Reduced appetite or general feeling of being unwell – sometimes more noticeable in later stages.
Quick comparison of key warning signs
| Symptom | How it may appear | Why it matters |
|---|---|---|
| Change in bowel habit | New diarrhoea/constipation or altered stool shape for >3 weeks | [7][9][1][3]Common early sign of a growth in the bowel | [9][7]
| Blood in poo / rectal bleeding | Bright red blood or very dark/black stools | [1][3][5][7]Frequent sign that should always be checked, even though piles are also common | [3][7][1]
| Persistent tummy pain or bloating | Ongoing cramping, discomfort, or bloating not settling | [5][7][9][1][3]May point to a tumour or bowel obstruction, especially with vomiting or severe constipation | [7][3]
| Feeling of incomplete emptying | Needing to go again right after a bowel movement | [9][1][3][7]Can indicate irritation or narrowing in the rectum | [7][9]
| Unexplained weight loss & tiredness | Losing weight without trying, feeling very tired or breathless | [1][3][5][9][7]May signal advanced disease and/or anaemia from chronic blood loss | [3][5][1][7]
How doctors think about these symptoms
Specialists emphasize that:
- Many people with bowel cancer symptoms have something more benign like piles, IBS, or minor gut infections, but you cannot tell without proper tests.
- The combination, persistence, and change from your personal “normal” pattern is more important than a single isolated episode.
- Screening programs (like stool tests or colonoscopies in certain age groups) can detect bowel cancer even before symptoms appear, improving outcomes.
“When it comes to bowel habit, there’s no ‘normal’, there’s only ‘normal for you’.”
When to seek urgent help
Contact a doctor as soon as possible if you notice:
- Blood in your poo or from your bottom that lasts more than a few days, keeps coming back, or is unexplained.
- A change in bowel habit lasting longer than about 3 weeks.
- Persistent tummy pain, bloating, or a lump in your abdomen or bottom.
- Unintentional weight loss plus tiredness or breathlessness.
Go to emergency care or call urgent services if:
- You have severe tummy pain with a swollen abdomen and vomiting (possible bowel blockage).
- You feel faint, very breathless, or notice large amounts of blood in your stool (possible severe bleeding and anaemia).
A short illustrative example
Imagine someone who normally has one formed bowel movement a day. Over six weeks, they begin to have looser stools three times a day, notice dark blood streaking the stool, feel constant pressure in their back passage like they still need to go, and lose several kilos without trying. Those combined symptoms of bowel cancer would be a strong reason to see a doctor urgently for tests such as stool checks, blood tests, and possibly a colonoscopy.
Final note
If you or someone close to you has any of these symptoms, the safest step is to talk to a healthcare professional promptly rather than waiting to see if they go away. Early assessment can often rule out cancer and, when cancer is present, gives the best chance of effective treatment.
Information gathered from public forums or data available on the internet and portrayed here.