Does What You Eat Affect Your Cologuard Results?

Colorectal cancer is the third most common cancer and the second leading cause of cancer-related death in the United States. Screening can catch colorectal cancer early, when it’s still easier to treat. 

But many people are hesitant about getting colonoscopies because they require preparation and anesthesia. Luckily, there are now other screening tools you can use, like the Cologuard test. Here’s what you should know about Cologuard and how to get ready for the test. 

What is Cologuard?

Cologuard is a stool test that looks for signs of colorectal cancer. 

Your stool contains cells that shed from the inside of your colon. The Cologuard test combines technology called fecal immunochemical testing and multitarget stool DNA testing. These tests can spot abnormal DNA in the colon cells in your stool sample. The tests also pick up any blood in your stool. Both blood and abnormal DNA can be signs of colon cancer. 

Not everyone can use Cologuard for colon cancer screening. You may be able to use Cologuard if you:

• Are older than 45 years 

• Don’t have a history of colon polyps or adenomas

• Don’t have a family history of colorectal cancer

• Don’t have a history of inflammatory bowel disease, ulcerative colitis, Crohn's disease, or familial adenomatous polyposis

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• Cologuard isn’t the only option. Find out which at-home colon cancer screening test is right for you.   

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• Can you stop getting colonoscopies? Many people over the age of 85 may be able to stop getting regular colonoscopies.

How do you prepare for Cologuard testing?

You don’t need to do any special preparation before taking a Cologuard test. This makes Cologuard easier and less time-consuming than colonoscopy screening, which requires changing your diet, fasting, and taking a colonoscopy prep. 

Cologuard is available only by prescription. A healthcare professional will send a prescription for the Cologuard kit, and the kit will be mailed to your home. 

You can use the kit as soon as you receive it. You don’t have to do any special preparation or change your diet before collecting your stool sample. 

But, keep in mind that the test does look for blood in your stool sample. It’s best not to collect your sample if you have bleeding hemorrhoids, diarrhea, or you’re menstruating. These conditions can cause blood to appear in your sample and trigger a false positive result. Instead, store your kit and use it when your bleeding has stopped. Keep the kit in a cool, dry place until you’re ready to use it. 

When you’re ready to do the test, unpack the kit and collect your stool sample. Follow the kit’s instructions on how to label and pack your sample. You can drop off your kit at a local UPS store or schedule a UPS pickup. Make sure to mail your kit as soon as possible once you collect your sample. The laboratory needs to run the tests within 3 days of your sample collection or the test results may not be valid. 

Your results will be available within 2 weeks. Your healthcare team will call you with your results or you can log into your Cologuard account to view your results.

What shouldn’t you eat before Cologuard testing?

You don’t need to avoid certain foods before taking a Cologuard test. Food and drinks will not affect the results of stool DNA tests. Vitamins and supplements will not affect your results either.

Certain foods and vitamins can affect the results of other types of at-home colon cancer tests. But these tests use technology that’s different from the technology used by Cologuard. So you don’t have to worry about what you eat or drink affecting Cologuard results. 

What else should you avoid before your Cologuard test?

There’s nothing you need to avoid before taking your Cologuard test. You don’t need to change your activity, your medication, or your daily routine. 

But you should avoid putting off completing your Cologuard test. Studies show that 3 out of 4 people actually complete their Cologuard test before its expiration date. 

You don’t want to delay colon cancer screening. You want to catch colon cancer early, when it’s still easier to treat. Taking your Cologuard test on time can be life-saving. 

What should you do if your Cologuard test is positive?

A positive Cologuard result doesn’t mean you have colorectal cancer. A positive result can be a sign of many things including colorectal cancer, polyps, or other colon conditions.

It’s important to talk with a healthcare professional about your positive results as soon as possible. You’ll need additional tests, like a colonoscopy, to determine whether you have colon cancer or another condition that triggered a positive Cologuard result. 

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Written by:

Jennifer Sample, MD

After a fellowship, Dr. Sample worked as the medical director at the University of Kansas Hospital Poison Center (The University Of Kansas Health System Poison Control Center), which served the state of Kansas for poison exposures. In 2007, she returned to Children’s Mercy Hospital in Kansas City, Missouri, as a consultant in clinical pharmacology and medical toxicology.

Edited by:

Patricia Pinto-Garcia, MD, MPH

Patricia Pinto-Garcia, MD, MPH, is a medical editor at GoodRx. She is a licensed, board-certified pediatrician with more than a decade of experience in academic medicine.

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