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Common vs. Uncommon Symptoms of Colon Cancer: What to Watch For

female cancer patient with doctor smiling at the camera

Colon cancer, also known as colorectal cancer, is a type of cancer that begins in the colon or rectum. Early detection is crucial for effective treatment, which is why it is important to be aware of the symptoms. This article discusses the common and uncommon symptoms of colon cancer to help you recognize the signs early.

Common Symptoms of Colon Cancer

Changes in Bowel Habits

One of the most common colon cancer symptoms is a noticeable change in bowel habits. This can include diarrhea, constipation, or a change in the consistency of your stool that lasts more than a few days. These changes occur because the cancer can create a partial blockage in the colon, affecting how stool moves through the digestive tract.

Rectal Bleeding or Blood in Stool

Another frequent symptom of colon cancer is rectal bleeding or the presence of blood in your stool. This bleeding can be bright red or darker, resembling tar. It’s important not to dismiss blood in your stool as it can indicate other serious conditions as well, such as hemorrhoids or gastrointestinal issues, but it warrants immediate medical attention to rule out colon cancer.

Persistent Abdominal Discomfort

Colon cancer can cause persistent abdominal pain, cramping, bloating, or gas. This discomfort is often caused by the tumor obstructing the bowel or causing inflammation. If you experience ongoing abdominal pain that doesn’t go away, it is essential to consult with a healthcare provider.

A Feeling that Your Bowel Doesn’t Empty Completely

A sensation that your bowel doesn’t empty completely after a bowel movement can be another sign of colon cancer. This feeling can result from the presence of a tumor in the colon that obstructs stool passage, leading to incomplete evacuation.

Weakness and Fatigue

Colon cancer can cause persistent weakness and fatigue. These symptoms can occur because the body is using more energy to fight the cancer, or due to anemia caused by chronic blood loss from the cancer. If you feel unusually tired and weak without a clear reason, it is important to seek medical evaluation.

Uncommon Symptoms of Colon Cancer

Unexplained Weight Loss

While weight loss is a more recognized symptom in many cancers, it is less common but still significant in colon cancer. Unexplained weight loss can occur due to the body’s increased energy expenditure to fight the cancer, or because the cancer affects your appetite and ability to absorb nutrients properly.

Iron-Deficiency Anemia

Iron-deficiency anemia is an uncommon but possible symptom of colon cancer, especially in men and postmenopausal women. Chronic blood loss from the tumor can lead to anemia, which may present as fatigue, weakness, and pale skin. A blood test can reveal low hemoglobin levels, prompting further investigation for colon cancer.

Nausea and Vomiting

Nausea and vomiting can be symptoms of advanced colon cancer. These symptoms may occur if the tumor causes intestinal obstruction of the colon, preventing the passage of food and waste, leading to a backup that results in nausea and vomiting.


Although rare, jaundice can be a symptom of colon cancer that has spread to the liver. Jaundice is characterized by yellowing of the skin and eyes, dark urine, and pale stools. This condition arises when cancer interferes with the liver’s ability to process and eliminate bilirubin.


When to See a Doctor

It is crucial to consult a healthcare provider if you experience any of the common or uncommon symptoms of colon cancer. Early detection significantly improves treatment outcomes. Regular screening for colon cancer is recommended for individuals over 50 or those with a family history of the disease, even if symptoms are not present.

Screening Tests

Several screening tests can detect colon cancer early, including:

  • Colonoscopy: A procedure that allows a doctor to examine the entire colon and rectum with a camera.
  • Stool Tests: Tests like the fecal occult blood test (FOBT) or fecal immunochemical test (FIT) check for blood in the stool.
  • Sigmoidoscopy: Similar to a colonoscopy, but examines only the lower part of the colon.
  • CT Colonography: A specialized scan to visualize the colon and rectum.

Regular screening can detect colon cancer before symptoms appear, which is vital for early treatment and better prognosis.


Understanding the common and uncommon colon cancer symptoms is crucial for early detection and treatment. Common symptoms include changes in bowel habits, rectal bleeding, persistent abdominal discomfort, a feeling of incomplete bowel evacuation, and weakness and fatigue. Uncommon symptoms include unexplained weight loss, iron-deficiency anemia, nausea and vomiting, jaundice, and frequent infections.

If you experience any of these symptoms, it is important to consult with a healthcare provider promptly. Regular screening and awareness of symptoms can help detect colon cancer early, improving treatment outcomes and survival rates. Stay vigilant and proactive about your health to catch potential issues early.

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