Colon Cancer Symptoms You Should Never Ignore Vector

Top 10+ Colon Cancer Symptoms to Never Ignore (2024)

by | Mar 20, 2024

Colon cancer, a formidable yet often preventable disease, stands as a significant health concern worldwide.

Manifesting initially through subtle changes within the body, its symptoms can be easily overlooked, making awareness and early detection crucial.

This article breaks down the most common symptoms of colon cancer, ranging from changes in bowel habits to more overt signs such as rectal bleeding and unexplained weight loss.

Understanding these symptoms is not just about recognizing the potential presence of cancer; it’s about empowering individuals to seek timely medical evaluation and intervention, potentially saving lives through early diagnosis.

What is Colon Cancer?

Colon cancer is a type of cancer that originates in the large intestine (colon), which is the final part of the digestive tract. It typically starts from small, benign clumps of cells called polyps that form on the inside of the colon. Over time, some of these polyps can become colon cancers.

Colon Cancer Vector Illustration

Colon Cancer Symptoms to Never Ignore

  1. Blood in stool
  2. Abdominal pain or discomfort
  3. Unexplained weight loss
  4. Fatigue
  5. Anemia
  6. Constipation
  7. Diarrhea
  8. Changes in bowel habits
  9. Rectal bleeding
  10. Narrow stools

Watch this video or keep reading to learn more about the most common symptoms of colon cancer.

Blood in Stool

Discovering blood in your stool can be an alarming symptom, often indicative of various gastrointestinal issues, including colon cancer.

The presence of blood can manifest in several forms: it may appear as bright red, signifying bleeding from the lower part of the digestive tract, or as dark red or black, suggesting a source higher up, which allows the blood time to darken as it moves through the intestines.

While there are benign causes for blood in the stool, such as hemorrhoids or minor tears in the anus (anal fissures), it is a hallmark symptom of more serious conditions like colon cancer. In colon cancer, tumors in the colon or rectum can bleed as they grow, shedding blood into the stool.

This symptom should never be ignored, as early detection of colon cancer can significantly improve treatment outcomes. Individuals noticing blood in their stool should seek medical evaluation promptly to determine the underlying cause and initiate appropriate management.

Abdominal Pain or Discomfort

Abdominal pain or discomfort is a common symptom that can be associated with a wide range of conditions, including colon cancer.

This type of discomfort can vary greatly in its nature and intensity, ranging from a mild, intermittent ache to severe, persistent pain.

In the context of colon cancer, the pain may arise from the tumor itself as it grows and exerts pressure on the surrounding tissues and organs, or from a blockage that the tumor causes in the colon.

This can lead to cramping and discomfort as the body attempts to move waste through the obstructed area. Additionally, gas and bloating may contribute to the sensation of discomfort due to disturbances in the digestive process.

It’s important to note that while abdominal pain is a common symptom, it is not specific to colon cancer and can be caused by many other conditions, such as infections, inflammatory bowel disease, or irritable bowel syndrome.

Nonetheless, persistent or unexplained abdominal pain should always be evaluated by a healthcare professional to rule out serious conditions like colon cancer and to ensure timely and appropriate treatment.

Unexplained Weight Loss

Unexplained weight loss, often defined as losing 5% or more of one’s body weight without trying, can be a concerning symptom and a potential sign of colon cancer.

This type of weight loss occurs when cancer cells disrupt the body’s ability to absorb nutrients properly, or when a large tumor in the colon makes it difficult for nutrients to be absorbed.

In addition, cancerous cells require a significant amount of the body’s energy; as they grow and multiply, they can increase the body’s metabolism, leading to weight loss.

This symptom is not specific to colon cancer and can be associated with a variety of other health conditions, including other types of cancer, thyroid problems, and digestive diseases.

However, when combined with other symptoms such as changes in bowel habits, abdominal pain, or blood in the stool, unexplained weight loss can be a significant indicator of colon cancer.

It’s crucial for individuals experiencing this symptom, particularly without any changes in diet or exercise habits, to consult a healthcare provider for a thorough evaluation to determine the underlying cause and receive appropriate care.


Fatigue associated with colon cancer is a profound sense of tiredness that doesn’t improve with rest. This symptom can be particularly insidious because it’s often attributed to busy lifestyles or stress.

However, when related to colon cancer, fatigue results from the body’s attempt to fight the cancer, as well as the cancer’s impact on the body’s ability to produce healthy red blood cells.

Tumors can bleed, leading to blood loss that might not always be visible in stool but can result in anemia—a condition characterized by a reduced number of red blood cells. Anemia can significantly contribute to feelings of fatigue because red blood cells are responsible for transporting oxygen throughout the body.

Without sufficient oxygen, the body’s tissues and organs are deprived of the energy they need to function effectively, leading to persistent tiredness. Fatigue from colon cancer can affect daily activities and quality of life, making it a crucial symptom to address.

It’s important for individuals experiencing unexplained, persistent fatigue alongside other symptoms like changes in bowel habits or abdominal discomfort to seek medical advice for a comprehensive evaluation.


Anemia is a condition characterized by a deficiency in the number or quality of red blood cells, which are crucial for carrying oxygen throughout the body.

In the context of colon cancer, anemia often results from chronic blood loss that may not be immediately visible, especially if the bleeding is slow and occurs within the colon or rectum. Over time, this blood loss depletes the body’s iron stores, necessary for producing red blood cells, leading to iron-deficiency anemia.

Individuals with anemia may experience symptoms such as fatigue, weakness, pale skin, shortness of breath, dizziness, or an irregular heartbeat. These symptoms occur because the body’s organs and tissues are not receiving enough oxygen to function properly.

Anemia can be a subtle, yet significant, indicator of colon cancer, especially when other symptoms such as changes in bowel habits or abdominal discomfort are present. It is essential for individuals experiencing signs of anemia to undergo medical evaluation to determine the underlying cause and to receive appropriate treatment.

Note: Detecting and addressing anemia early can significantly improve a person’s quality of life and overall health outcome.


Constipation, a common digestive condition, is characterized by infrequent bowel movements or difficulty passing stools. When associated with colon cancer, constipation can result from a tumor obstructing the colon, making it difficult for waste to pass through.

This obstruction can lead to a buildup of stool, causing discomfort and infrequent bowel movements. The consistency of the stool may also change, becoming harder and more difficult to pass, which can exacerbate the discomfort and effort needed during bowel movements.

It’s important to understand that while constipation is a common issue that can arise from a variety of causes such as diet, lifestyle, and medications, persistent constipation that does not respond to usual treatments warrants medical attention.

In the context of colon cancer, constipation often occurs alongside other symptoms such as abdominal pain, blood in the stool, and unexplained weight loss.

Individuals experiencing persistent constipation, especially with these additional symptoms, should seek a medical evaluation to rule out colon cancer or other serious underlying conditions. Early detection and treatment can significantly improve outcomes.


Diarrhea, defined as loose, watery stools occurring more frequently than usual, can be a symptom of colon cancer when the disease affects the colon’s ability to absorb water from the waste material passing through it.

This inability can result from a tumor obstructing the colon, leading to an alteration in the fluid absorption process, or from the cancer directly affecting the cells lining the intestine, disrupting their normal function. Unlike occasional diarrhea that can result from dietary changes or temporary infections, diarrhea associated with colon cancer is persistent and may not resolve with over-the-counter treatments.

It can lead to dehydration and electrolyte imbalances, further complicating the individual’s health status. Diarrhea that occurs alongside other symptoms such as abdominal pain, blood in the stool, unexplained weight loss, or changes in the caliber of stool should raise concerns and prompt medical evaluation.

As with other symptoms of colon cancer, early detection through attentive monitoring and medical intervention is crucial for effective treatment and management of the disease.

Changes in Bowel Habits

Changes in bowel habits that persist for more than a few days can signal colon cancer. This symptom encompasses a range of alterations in the frequency, consistency, shape, or color of stools.

Individuals may notice an increase in constipation or diarrhea, a feeling of incomplete evacuation after a bowel movement, or a change in the size or shape of the stool, such as narrower stools than usual. These changes can occur if a tumor in the colon or rectum alters the organ’s function, affecting how waste moves through and is processed by the digestive tract.

It’s crucial to understand that while changes in bowel habits can be influenced by diet, stress, and other non-cancerous conditions, persistent alterations—especially when accompanied by other symptoms like abdominal pain, blood in the stool, or unexplained weight loss—should not be ignored.

Such symptoms warrant a thorough medical evaluation to identify the underlying cause. Early detection of colon cancer, often through screening and attention to changes in bowel habits, plays a critical role in improving the effectiveness of treatment and the likelihood of a favorable outcome.

Rectal Bleeding

Rectal bleeding is a symptom that may manifest as bright red blood on the toilet paper, in the toilet bowl, or mixed with the stool. It is a potentially alarming sign that can indicate various conditions, from benign issues like hemorrhoids or anal fissures to more serious concerns such as colon cancer.

In the context of colon cancer, rectal bleeding occurs when the tumor in the colon or rectum bleeds, either as a result of the tumor’s growth into nearby blood vessels or due to the irritation of the tumor’s surface.

This symptom is particularly significant because it is often one of the more visible signs of colon cancer, prompting individuals to seek medical attention. However, it’s important to note that rectal bleeding is not exclusive to cancer and can be caused by other conditions, which are often less serious.

Regardless, any instance of rectal bleeding should be evaluated by a healthcare professional to determine its cause.

Early diagnosis and treatment of colon cancer can greatly increase the chances of a successful outcome, making it crucial for individuals experiencing rectal bleeding, especially if accompanied by other symptoms like changes in bowel habits or abdominal pain, to consult with a healthcare provider promptly.

Narrow Stools

Narrow stools, sometimes described as pencil-thin, can be a subtle but significant symptom of colon cancer. This change in stool caliber may occur when a tumor within the colon narrows the passage through which stool can move, forcing the stool to take on a thinner shape as it passes the obstruction.

While stool shape can vary for a multitude of reasons, including dietary changes and non-cancerous conditions like hemorrhoids, persistent narrow stools—especially when accompanied by other symptoms such as rectal bleeding, changes in bowel habits, abdominal pain, or unexplained weight loss—should prompt concern.

It’s essential to recognize that narrow stools alone are not a definitive sign of colon cancer, as many individuals may experience them temporarily without any underlying serious condition. However, when they persist and are associated with other warning signs or risk factors for colon cancer, it becomes crucial to undergo a medical evaluation.

Early detection of colon cancer through attentive observation of symptoms like narrow stools and timely medical consultation can significantly improve the effectiveness of treatment and the overall prognosis.

Final Thoughts

Recognizing the symptoms of colon cancer is a critical step toward early diagnosis and effective treatment.

While the presence of symptoms like rectal bleeding, narrow stools, and persistent abdominal discomfort can be concerning, they serve as crucial indicators that warrant medical evaluation.

Early detection of colon cancer can vastly improve the prognosis, highlighting the importance of being attuned to one’s body and seeking medical advice when changes occur.

By fostering an understanding of these symptoms, individuals can take proactive steps in managing their health and potentially safeguard against the ramifications of a late-stage colon cancer diagnosis.

John Landry, BS, RRT

Written by:

John Landry, BS, RRT

John Landry is a registered respiratory therapist from Memphis, TN, and has a bachelor's degree in kinesiology. He enjoys using evidence-based research to help others live a healthier life.


  • Lotfollahzadeh S, Recio-Boiles A, Cagir B. Colon Cancer. [Updated 2023 Jun 3]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024.

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