Colorectal cancer is the second most common cause of cancer death in the United States when numbers for men and women are combined, and the American Cancer Society expects it to cause about 55,230 deaths in 2026.
Yet the disease rarely announces itself with a dramatic warning. The American Cancer Society notes that colorectal cancer might not cause symptoms right away, and when early signs do appear, they tend to look like everyday gut trouble.
That is why the signs below matter. Individually, each one has plenty of harmless explanations. Together, or when they refuse to go away, they are the pattern doctors want you to bring in.
The 8 signs worth taking seriously
1. A lasting change in your bowel habits. New diarrhea, new constipation, or a stool that keeps changing shape for weeks. The ACS lists a change in bowel habits, such as diarrhea, constipation, or narrowing of the stool, as one of the main warning signs.
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2. Stools that look thinner than usual. Pencil-thin or ribbon-like stools can point to a growth narrowing the passage inside the colon or rectum. The National Cancer Institute flags stools that are narrower or have a different shape than usual as a symptom to check.
3. Feeling you still need to go, even right after you have. That nagging urge that a bowel movement did not empty you is on the ACS list and echoed by the Cleveland Clinic, which describes it as feeling like there's still poop in your bowel even after you go.
4. Bright red bleeding from the rectum. Blood on the toilet paper or in the bowl is often hemorrhoids, but it can also be a tumor bleeding low in the colon or rectum, and the two look identical to the person seeing it.
5. Blood in the stool that turns it dark or black. Bleeding higher up in the colon does not stay red. The ACS explains that blood in the stool might make the stool look dark brown or black, so a change in color alone is a reason to see a doctor.
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6. Ongoing abdominal pain, cramps, gas, or bloating. The NCI describes general abdominal discomfort, including frequent gas pains, bloating, fullness, or cramps. Occasional bloating is normal. Discomfort that hangs around for weeks is not.
7. Unusual weakness and fatigue. Slow, silent bleeding inside the colon can drain iron over time and leave you tired for no obvious reason. The ACS lists weakness and fatigue among the classic warning signs.
8. Losing weight without trying. Unintended weight loss shows up on every major authority's list, from ACS to NCI to Cleveland Clinic. If the scale is falling and your diet and activity have not changed, it is worth investigating.
When to call a doctor
The ACS is blunt about this. If you have any of these problems, it advises seeing your doctor right away so the cause can be found and treated if needed. A useful rule of thumb: symptoms that persist beyond two to three weeks, or bleeding of any kind, warrant a visit, even if you feel otherwise well.
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Screening can catch it before symptoms start
The most important line in the ACS guidance is easy to miss: most early-stage colorectal cancers produce no symptoms at all. That is why the ACS now recommends people at average risk start regular screening at age 45, not 50.
Getting screened on time is not a small detail. Regular screening has been shown to cut the risk of dying from colorectal cancer by nearly half, because tests like colonoscopy can find and remove precancerous polyps before they ever become cancer.
If you are 45 or older and have never been screened, ask your doctor which test is right for you at your next visit.
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This article is made and published by Jesper Bengtson, who may have used AI in the preparation.