Learn more about the potential symptoms of colon cancer and rectal cancer. The Symptoms of Colon Cancer and Rectal Cancer | Colorectal Cancer Alliance
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What are the symptoms of colorectal cancer?


Colorectal cancer may not cause symptoms, particularly at first. Someone can have colon cancer or rectal cancer  and not know it. That's why every person should get screened starting at age 45. People at higher risk may need to get checked earlier, according to their risk factors.  

When they occur, symptoms may include: 

Changing bowel habits 

Changing bowel habits may include intermittent or constant diarrhea and/or constipation, a change in the consistency of your stool, or stools that are more narrow than usual.

Persistent abdominal discomfort

Abdominal discomfort may present as cramps, gas, or pain. You may also feel full, bloated, or like your bowel is not completely empty. Nausea and vomiting can also be a symptoms.

Rectal bleeding

Blood in or on your stool is a symptom of rectal cancer and colon cancer. The blood can be bright red, or the stool may be black and tarry or brick red.

Weakness and/or fatigue 

Weakness and/or fatigue may be a sign of colorectal cancer. Weakness and/or fatigure may be accompanied by anemia or a low red blood cell count.

Unexplained weight loss

A loss of weight for no known reason should always be investigated. Nausea and/or vomiting are also possible symptoms.

When should I see a doctor?


Earlier is better! Symptoms of colon cancer and rectal cancer can be associated with many other health conditions. Only a medical professional can determine the cause of your symptoms.

The early signs of cancer often do not include pain. A medical provider should be consulted when any symptom develops. Early detection can save your life.

When it comes to colorectal cancer, the most common symptom is no symptom. That's why colorectal cancer is called the silent killer. If you’re 45 and at average risk, get screened

Resources for download


Symptoms Tracker

Help your doctor determine the cause of your symptoms. Use our colorectal cancer symptoms tracker to create a simple log of symptoms. Then give it to your doctor.

Download English

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