Colorectal cancer symptoms

Did you know 1 in 20 people will be diagnosed with colorectal cancer in their lifetime? This is why it’s so important to know the signs and symptoms of colorectal cancer and take action if you’re experiencing any of them.

hero symbol

What are the symptoms of colon cancer?

The signs and symptoms for colon cancer and rectal cancer are the same. Here are the most common colorectal cancer symptoms.

Bloody poop

Also known as: rectal bleeding, blood in the stool

If you notice blood on your poop or on the toilet paper when you wipe, talk to your doctor. Usually your primary care physician (PCP) is who to talk to first—if you don’t already have a gastroenterologist. Women, mention this to your OB-GYN if you don’t regularly see your PCP.

Bloody poop doesn’t necessarily mean you have colorectal cancer; however, any amount of rectal bleeding is not normal, and you need to figure out why you’re seeing blood in the toilet. Blood in the stool is a common symptom of colorectal cancer (as well as several other GI issues, including internal hemorrhoids).

Talk with your doctor ASAP—don’t delay reaching out and making an appointment—if you’re seeing blood in your poop. Be sure to pay attention to and highlight the following factors when speaking with your doctor:

  • The color of the blood and/or poop
  • Whether the blood is on or in the poop
  • If the blood is on the toilet paper or in the toilet bowl
  • How often the blood occurs
  • Whether or not bowel movements are painful
  • If any other symptoms accompany the bleeding (stomach pain, constipation, fatigue, painful urge to pass gas, large amounts of blood loss while passing gas, etc.)

Blood in your poop is not normal. If your doctor recommends over-the-counter remedies and suggestions, but you still have blood in your poop, don’t be embarrassed. Go back to your doctor for help.

Your doctor needs to stay motivated and determined to find the cause of your rectal bleeding. Don’t stop pushing and asking for screenings and tests until you find what is causing the bloody poop or symptoms—regardless of your age.

Funky poop

Also known as: ongoing changes in bowel habits

Every poop is different, and every person poops differently. Poop can change because of what you’re eating, infections, medications you’re taking, or other medical issues. If you have not pooped for three days in a row —you should see a doctor.

Some people poop once per day; others poop a few times each day. If you notice your personal pooping schedule, or the way your poop looks, is changing—bring it up with your doctor. We know it can be embarrassing, but it’s nothing to be ashamed of. We encourage, urge, or challenge you to talk to your doctor about what is off with your poop. This conversation could save your life.

Poop Color and Size: The Bristol Stool Chart

The Bristol Stool Chart is a helpful guide that shows what your poop is trying to tell you.

2023_Bristol Stool Chart_WEB-FightCRC

If you’re consistently seeing anything but Normal (types 3 and 4), have a conversation with your doctor. If you’re passing watery, diarrhea-like stools for more than 24 hours, call a doctor ASAP. Same goes for if you have sudden urges to poop, but you can’t control it.

Also, poop should be typically brownish in color. Signs to talk to your doctor include poop colored:

  • Black—looks like tar
  • Clay—like a terracotta pot
  • Red—anywhere from bright red to dark red
  • White—looks ashy
  • Call a doctor right away if you see mucus or pus.

Stomach pains

Also known as: abdominal pains, stomach cramps

Severe abdominal pain is nothing to brush off.

If you’re experiencing gut-wrenching, knife-in-my-stomach type abdominal pains, visit an emergency room ASAP. You need to advocate for yourself to identify the cause of the pains; do not settle for medication that simply takes the pain away.

If you’re experiencing frequent, mild abdominal pains, it’s still important to get checked out and discover why.

Skinny poops

Also known as: narrow stools, thin stools, pencil-thin stools, ribbon-like stools

Some people may be used to thinner stools, but super thin, pencil-like stools are something to keep an eye on and report to your doctor. Skinny poops can be caused by a lot of things—some are harmless and temporary conditions, and others may be serious. Low-fiber diets, temporary infections, irritable bowel syndrome (IBS), and colorectal cancer can all be at play.

Thin stools are a serious symptom because skinny poop may be caused by an obstruction in the colon, like a tumor. If you’re seeing skinny poop for more than a week, see a doctor.

For the most part, narrow stools that occur infrequently are not a cause for concern. But if you experience ribbon-like stools for more than a week, seek medical attention.

Losing weight without trying

Also known as: unexplained weight loss

Just because you’re losing weight without trying doesn’t mean you have colorectal cancer. But it is one of the symptoms of colorectal cancer which is why it is important that you get this symptom evaluated.

Amongst cancer patients, weight loss is often a result of cancer cells consuming the body’s energy as they multiply. In addition, your immune system is spending more energy to fight and destroy cancer cells.

If colorectal cancer is the specific cause of your weight loss, this may be due to the tumor blocking the colon or intestinal tract, preventing proper nutrient absorption. If you’re losing weight and you don’t know why, ask your doctor to help you uncover the underlying cause.

Can’t fart

Also known as: frequent gas pains, bloating, a feeling of fullness, or abdominal cramps

Most people release about 1 to 4 pints of gas a day and fart up to 21 times per day. (We’re not kidding!)

Any obstruction in the colon, including cancer, can hinder your ability to pass gas. The colon is located in the abdomen, so if colon cancer is the cause of your bloating or pain, it is not uncommon to feel discomfort in that area.

If you can’t fart, or if you have a persistent feeling of fullness or stomach cramping, talk to a doctor.

Super tired and short of breath

Also known as: muscle weakness, fatigue, anemia

Similar to losing weight without trying, colorectal cancer symptoms can disguise themselves as constant weakness and fatigue.

Since cancer cells multiply unchecked, the constant, extra energy consumption can cause you to feel very tired—even when you’re had enough sleep and rest. Chronic fatigue and muscle weakness are most likely a sign of an underlying medical condition, even if it is not caused by colorectal cancer.

Anemia, also known as having low red blood cell counts, can be caused by internal bleeding. Many patients have learned they’re anemic after they try to give blood and are told they cannot. Others may go for routine bloodwork and find out they’re anemic in the lab report. Anemia often points to a medical condition that needs to be discovered.

If you experience fatigue, muscle weakness (that’s not related to working out), and/or you find out you’re anemic, talk to your doctor. These are all symptoms that could suggest colorectal cancer.

Tips for Talking to Your Doctor

What should I do if I see a colorectal cancer symptom?

If you are experiencing a symptom of colorectal cancer, it does not mean you have colorectal cancer. However, it does mean you need to see a doctor and get checked out.

Also, the more of the signs of colorectal cancer you’re experiencing, and the more severe the symptoms, the more urgent the doctor’s appointment needs to be.

Wishful thinking will not make the symptoms go away and, in fact, will only delay diagnosis and treatment—not just of colorectal cancer, but whatever the underlying issue causing your symptoms turns out to be. Don’t hope your symptoms will go away: Be proactive and get a jump on figuring out what’s wrong as early as possible.

Regardless of your age, if you’re experiencing symptoms, you need to tell your doctor. Don’t self-diagnose with the Internet. See a licensed medical professional.

Does colorectal cancer always have symptoms?

No! It’s not uncommon for people diagnosed in the early stages of colon cancer (stage I or II) to not experience any symptoms. Sometimes, but not always, it’s not until colorectal cancer has grown into stages III or IV that symptoms appear.

If caught early, colorectal cancer is highly treatable. Some patients who undergo screening have a polyp removed, or cancer discovered, yet had no idea anything was wrong.

Do I have to get screened even if I’m not seeing signs and symptoms?

YES: Do not wait until you have signs and symptoms before getting screened for colorectal cancer.

Problems found after you begin seeing signs and symptoms often could be avoided with on-time screening. Often, early-stage cancers do not present signs and symptoms.

It’s critical that starting at age 45, everyone needs to get screened for colorectal cancer, regardless of symptoms. Age is one of the biggest factors that increases your risk.

Does my age impact whether or not I should see a doctor if I have colorectal cancer symptoms?

Your age may increase your risk of getting colorectal cancer, but it won’t impact the symptoms. Anyone, at any age, can get colorectal cancer.

If you’re seeing any of the symptoms, regardless of your age, talk to a doctor and push for colorectal cancer screening. If your doctor refuses to consider colorectal cancer because of your age, seek out a second opinion.

Need help? Check out our Provider Finder and search for a doctor near you.

If I’m experiencing a symptom, does that mean I have colorectal cancer?

No! There are many other conditions that cause the same signs as colorectal cancer. An infection, Crohn’s disease, ulcerative colitis, and other GI issues can also cause similar symptoms to colon and rectal cancers. In some cases, treatment for these diseases—for example, surgery—may follow a similar path to colorectal cancer treatment.

Also, irritable bowel disorders (IBD) raise someone’s risk for colorectal cancer. Talking about a prevention plan (such as earlier or more frequent screenings, for example) for colon cancer, if you have IBD, is important.

What about anal cancer?

Colon cancer and rectal cancer are different cancer types than anal cancer. Some anal cancer symptoms are the same as colorectal cancer, such as rectal bleeding, a change in bowel habits, and narrow stools. If you have any of these symptoms, you need to see a gastroenterologist who can properly diagnose you and identify why you’re seeing these signs.

Learn more about anal cancer.

Medical Review

Rachel Issaka headshot
Rachel Issaka, MD, MAS

Fred Hutch Cancer Center

Last Reviewed: January 29, 2024