In short
See a GP if you have a change in bowel habit lasting three weeks, blood in your poo, tummy pain or bloating that does not settle, unexplained weight loss, or tiredness without a clear cause. Haemorrhoids and IBS are common, but they should not be assumed. Do the NHS FIT test when it arrives even if you feel well.
Bowel cancer (colorectal cancer) is the fourth most common cancer in the UK, with around 42,000 diagnoses a year, and the second most common cause of cancer death after lung cancer — about 16,800 deaths a year.
Most bowel cancers grow slowly from polyps. That is why symptoms that last, and screening that finds hidden blood, change survival.
What bowel changes should you get checked?
The NHS advises seeing a GP if any of the following last three weeks or more.
- Looser stools, going more often, or new constipation
- Blood in poo — dark red or black as well as bright red
- Tummy pain, bloating or discomfort that does not settle
- Weight loss without trying, or unusual tiredness
Is blood in poo always bowel cancer?
No. Piles, fissures and infection are common. Bright red blood on the paper is often from the anus. Darker blood mixed through the stool, or blood with a change in habit, still needs a GP — especially if you are over 50.
Never wait for the next screening kit if you have symptoms. A recent normal FIT does not cancel a new symptom.
Does bowel cancer always cause pain?
No. Early bowel cancer can cause no pain at all. That is why the home FIT test matters: it can find hidden blood before you feel unwell. Stage 1 five-year survival exceeds 90%; stage 4 is around 10%.
What are the key takeaways?
- A three-week change in bowel habit or blood in poo should be checked by a GP.
- Most of these symptoms are not cancer — checking is how the ones that are get found early.
- Do not ignore symptoms because a recent FIT test was normal.
- About 95% of UK cases are in people aged 50 and over, but younger adults can be affected.
Care like this is out of reach for millions
The diagnosis, screening and treatment described here are routine in the UK. In Pakistan, Indonesia and Malaysia, poverty puts them out of reach — so a treatable cancer too often becomes a fatal one. World Aid Network funds treatment through locally-licensed oncologists for patients who cannot pay.
Frequently asked questions
How long should diarrhoea last before I worry?
A change lasting three weeks should be checked, whether looser stools, more frequent stools or constipation. Book sooner if there is blood or you feel very unwell.
Can IBS hide bowel cancer?
IBS is common and is not cancer. A new, persistent change — especially with bleeding or weight loss — should still be assessed rather than labelled IBS without a check.
Should I wait for my screening kit?
No. Screening is for people with no symptoms. Symptoms need a GP appointment now.
This guide is general information, not medical advice. It was reviewed by the World Aid Network editorial team for accuracy against NHS and World Health Organization sources. Always speak to a GP or qualified clinician about your own health.