Colon Cancer Symptoms

Colon cancer usually doesn’t cause symptoms in the early stages. As the disease progresses, you may experience abdominal pain, rectal bleeding, and changes in the size and shape of your stool. Unintentional weight loss, iron deficiency anemia, and jaundice can also occur.

This article explores the signs and symptoms of colon cancer. It also looks at some of the complications of colon cancer and when you should see a healthcare provider.

colon cancer symptoms


Frequent Symptoms of Colon Cancer 

At stage 1, colon cancer usually has no symptoms. This is why regular screening beginning at age 45 (and earlier for those with risk factors) is an important investment in your health.

The symptoms mentioned below by no means point directly to colon cancer. In fact, they could indicate another problem in the bowels, such as an infection (for example, acute diverticulitis), ulcers, or inflammation (for example, Crohn's disease). This is why seeing your healthcare provider is critical.

Colon cancer symptoms come in two general varieties: local symptoms (based on where the tumor is located) and systemic symptoms (involving the whole body).

Local Symptoms of Colon Cancer

Local colon cancer symptoms affect your bathroom habits and the colon itself. These symptoms can include:

Changes in Your Bowel Habits

There is no such thing as a universally "normal" bowel movement. In fact, your healthcare provider really only cares about what is normal for you.

The size, color, and consistency of everyone's stools are unique. Therefore, it is important to notice any change in your normal patterns. This is often one of the first symptoms of colon cancer.

Change in Stool Frequency

A persistent change (more than a few days) in stool frequency is one potential sign of colon cancer. For example, if it is normal for you to have three bowel movements per day, and you are having only one per day, or one every other day, this may signal constipation. 

On the other hand, if your typical pattern is to have a bowel movement every other day and you're having one bowel movement per day, it may be unusually frequent and could signal a change.

Changes in Stool Shape

Thin or narrow stools, often described as ribbon- or pencil-like, may also be a sign of colon cancer. In an otherwise healthy person, thin stools may be caused by a narrowing of the colon—also called a partial blockage of the colon due to colon cancer.

Changes in Stool Color

Bleeding in the colon due to colon cancer may result in bright red or dark red blood in the stools. More specifically, if bleeding is in the ascending (right-side) colon, the stools may be more maroon or purple in color since the bleeding is occurring farther away from the rectum. 

If the tumor is in the descending (left-side) colon, the bleeding tends to result in bright red stools (the passage of fresh, red blood is called hematochezia). Blood in the stool is always a reason to see a healthcare provider, since it may be one of the first symptoms of colon cancer.

Difficulty With Stool Evacuation

A persistent feeling that you need to have a bowel movement, even when you just had one (called tenesmus), may be a symptom of colon cancer. 

Alternating Constipation and Diarrhea

Symptoms of alternating diarrhea and constipation may occur when there is a partial obstruction in the bowel due to a tumor. Constipation may occur due to difficulty in stool passing the obstruction, followed by diarrhea when backed-up contents are then passed.

Abdominal Discomfort

Abdominal pain or cramping may occur in those who have colon cancer. Colon cancer pain is usually felt in the abdomen, but its exact location can vary. Most people describe it as a dull cramping sensation. 

Females can sometimes dismiss symptoms like abdominal discomfort because they can feel similar to menstrual symptoms.

Gas and Bloating

Excessive gas and bloating can be a sign of colon cancer. However, dietary triggers (for example, carbonated beverages, dairy products, and high-fiber foods) and digestive disorders (for example, inflammatory bowel disease) are common culprits.

If gas and bloating are related to colon cancer, they tend to be late symptoms caused by an obstructing tumor in the colon. Bloating may also occur as a result of cancer spreading to nearby lymph nodes. 

Nausea and/or Vomiting

When nausea and vomiting are symptoms of colon cancer, it's usually because a tumor is causing a bowel obstruction.

If nausea and vomiting are accompanied by other worrisome signs—such as constipation, abdominal cramping, and/or abdominal distension—colon cancer could be a cause. 

Nausea and vomiting may occur at any stage of colon cancer but are more common with advanced disease. It's important to remember that the occurrence of nausea and vomiting alone, without other colon cancer symptoms, is not likely an indication of cancer.

Systemic Symptoms of Colon Cancer

Systemic colon cancer symptoms are those that affect your whole body.

Unintentional Weight Loss

If you lose weight without trying, it is an important symptom that shouldn't be ignored. Colon cancer is only one of several serious conditions that might first present themselves with unexplained weight loss.

The basis behind unintentional weight loss with cancer is that tumors use the body's blood and nutrients to thrive and grow. In addition, some tumors release chemicals that increase the body's metabolism, which can further lead to unexplained weight loss. 

Unexplained weight loss is described as losing 10 or more pounds or at least 5% of your body weight over a six- to 12-month period. For example, if you are a 150-pound person who lost 7.5 pounds in a year for no apparent reason, you should contact your healthcare provider.

Unusual loss of appetite is another sign to look out for. While the loss of appetite is most commonly a stage 4 colon cancer symptom, it has been noted in some people with early colon cancer.

Unexplained Fatigue

Extreme tiredness is a nonspecific symptom, but is very common in people with more advanced cancers such as stage 4 colon cancer. Cancer fatigue differs from "ordinary" fatigue in that it's not usually relieved by rest or counteracted by a good cup of coffee.

It's not uncommon for people to have a sense that something is amiss in their body, even if they don't have specific symptoms to back up that feeling. Trust your intuition. If you are concerned that something is wrong, make an appointment to talk with your healthcare provider.

Rare Systemic Symptoms

Stage 4 colon cancer symptoms may include:

  • Fever: If a tumor in the colon breaks through the intestines, an abscess may form, which causes a fever.
  • Air bubbles in urine: Air bubbles in your urine (called pneumaturia) may occur if a tumor in the colon invades into the bladder.
  • Problems breathing: If the colon cancer has spread to the lungs, shortness of breath, coughing, and/or chest pain may occur.
  • Headache and neurological problems: If the colon cancer spreads to the brain or spinal cord, headache, vision changes, confusion, and/or seizures may occur.
  • Bone pain: Fractures, bone pain, and high calcium levels (seen on a blood test) may occur if cancer spreads to the bones.


Complications of colon cancer may include anemia, jaundice, and bowel obstruction.

Iron Deficiency Anemia

Due to microscopic bleeding from a tumor, iron deficiency anemia may occur as the first sign of colon cancer.

Anemia is diagnosed with a blood test, called a complete blood count (CBC), and may cause symptoms of unusual tiredness, dizziness, palpitations, and shortness of breath.


Another potential complication of colon cancer is jaundice, a condition in which the skin and whites of the eyes take on a yellowish appearance.

Jaundice may occur when colon cancer spreads to the liver, a common site of metastasis. It may also occur due to pressure from a colon cancer on important structures related to the liver.

Bowel Obstruction

A bowel obstruction from colon cancer means that the tumor is physically blocking the intestines.

Depending on the severity of the blockage, solids, liquids, and even gas may be prevented from passing through the colon. This can lead to painful stomach cramps, bloating, constipation, and sometimes nausea and/or vomiting.

While a nasogastric tube may be placed temporarily to reduce swelling and remove the fluid and gas buildup of a bowel obstruction, surgery to remove the obstructing tumor or a stent placement (to open up the blocked area) is often required. 

When to See a Healthcare Provider

While many people have heard that having blood in their stools may be a sign of colon cancer, just about any change in your bowel habits is worth evaluating. While you may be anxious about the possibility of having colon cancer, early diagnosis offers you the best opportunity for successful treatment. In many cases, something else entirely is going on—something less serious than cancer.

Research has shown that there is a significant delay between when people first notice signs of colon cancer and when it is actually diagnosed. This lag time could result in colon cancer spreading further, which lowers the chance of successful treatment. 

Colon Cancer Healthcare Provider Discussion Guide

Get our printable guide for your next healthcare provider's appointment to help you ask the right questions.

Doctor Discussion Guide Woman
10 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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Additional Reading

By Suzanne Dixon, MPH, RD
Suzanne Dixon, MPH, MS, RDN, is an award-winning registered dietitian and epidemiologist, as well as an expert in cancer prevention and management.