The short answer
A lasting change in bowel or bladder habits — such as new constipation or diarrhea, narrower stools, or changes in urination — can be a warning sign of colorectal, bladder, or prostate cancer. Most causes are not cancer, but lasting changes should be checked.
A lasting change in bowel or bladder habits can be a warning sign of cancer.
Bowel changes like new constipation, diarrhea, or narrow stools can signal colorectal cancer.
Changes in urination, or blood in the urine, can signal bladder or prostate cancer.
Most such changes have non-cancer causes, but lasting ones should be checked.
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The full explanation.
The simple version
Everyone's bowel and bladder habits vary. But a change that is new and lasts — not just a passing upset — can occasionally be a warning sign of cancer. Most such changes are caused by something else, but lasting ones should be checked.
Bowel changes to watch
Worth checking if they last more than a couple of weeks:
- New constipation or diarrhea
- Narrower stools than usual
- A feeling that the bowel does not fully empty
- Blood in the stool or dark, tarry stools
Bladder changes to watch
Also worth checking: needing to urinate more or less often, trouble urinating, pain when urinating, or blood in the urine. These can signal bladder or prostate problems, including cancer.
Blood in the stool or urine should always be checked.
When to see a doctor
Most of these changes come from diet, infections, hemorrhoids, or an enlarged prostate — not cancer. Still, a change that lasts more than a couple of weeks, or any blood in the stool or urine, should be evaluated by a doctor.
Words to know
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Common questions
▸What bowel changes should I watch for?
Watch for a lasting change such as new constipation or diarrhea, narrower stools, a feeling that the bowel does not empty, or blood in the stool. Changes that last more than a couple of weeks should be checked.
▸What bladder changes matter?
Watch for needing to urinate more or less often, trouble urinating, pain when urinating, or blood in the urine. These can signal bladder or prostate problems, including cancer.
▸Do these changes mean cancer?
Usually not. Diet, infections, hemorrhoids, an enlarged prostate, and many other conditions cause these changes. But because they can signal cancer, lasting changes should be evaluated.
▸When should I see a doctor?
See a doctor for a change in bowel or bladder habits that lasts more than a couple of weeks, or for any blood in the stool or urine.
Questions to ask your doctor
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