What Not to Do While Prepping for a Colonoscopy

It's Important Not to Eat Before a Colonoscopy

When most people first learn that they need to have a colonoscopy, several things may go through their mind. Your doctor may let you know about the procedure and why it's being done—a scope with a light is put into the rectum to check for presence of disease and to help diagnose and treat it. He or she will also give you instructions for prep. For a colonoscopy to be accurate and useful, the colon must be clear of stool.

The physician performing the colonoscopy will give detailed instructions on how to follow the prep in the days leading up to the test. These instructions should be followed carefully. It is very easy to make a mistake, and below are several of the ways that people inadvertently ruin a colonoscopy prep.

Not preparing well could mean that the procedure will need to be rescheduled and that means losing more time off from work and school. Do your best not to do these things, but do ask questions if anything is unclear.

Don't Eat

eating for energy
Getty Images: Alexandra Grablewski

It may seem as though this would go without saying, but many people get quite hungry during the prep. In most cases, the prep calls for a liquid diet the day or afternoon prior to the colonoscopy and nothing at all to eat or drink after midnight.

Some people may forget that they shouldn't eat anything, and get up in the morning and have some coffee or breakfast out of habit. The colon needs to be free of waste material for a colonoscopy, and eating solid food would, naturally, keep that from happening.

What happens if you eat before a colonoscopy? Eating before a colonoscopy could make the test less useful. In that case, the test might need to be done again, and that's not something anyone wants.

The medications used during a colonoscopy could cause nausea and having an empty stomach will prevent vomiting up anything that was eaten. Even though news reports may say there's research that says people can eat before a coloscopy, following doctor's orders and not eating before a colonoscopy is the best idea.

Don't Try to Leave Your House

To be comfortable while prepping for a colonoscopy, the best idea is to to be at home near a bathroom. The prep will cause many watery stools, and most people are most comfortable if they clear their schedule and plan on spending the day resting, reading, watching movies, and following prep directions.

A clear schedule and focusing on the prep is important. There could be symptoms while prepping such as nausea, dizziness, or fatigue, so leaving the house wouldn't be the best idea.

Don't Eat or Drink Certain Artificial Colors

Many foods and drinks contain artificial coloring. The red, purple, or orange food coloring used in sports drinks, gelatin, or popsicles may linger in the intestinal tract and cause the tissue in the colon to appear redder than it actually is.

The problem with this is that the red color could mimic the appearance of inflammation, when there actually is no true inflammation present. In cases where a particular food or drink is in question, call the doctor, or better yet, choose something to eat that does not have artificial coloring.

Don't Give Up in the Middle of Prep

Preparing for a colonoscopy isn't pleasant, and many people agree that it's worse than the actual test. Some people get to the point where they don't feel like continuing or finishing the prep, especially when feeling very tired and hungry.

Stopping in the middle, however, could jeopardize the physician's ability to perform the colonoscopy because the colon may not be totally free of stool. That could lead to an incomplete test, which may have 1 of 2 possible outcomes: the physician will be unable to make sure the colon is free of disease or the test may need to be repeated (and therefore, the prep will need to be done again too). Being unable to complete the prep for any reason, such as being unsure of the directions, or feeling very ill, is a cause to call the doctor immediately.

Don't Take Certain Medications

Bring a list of medications for the doctor to see before having a colonoscopy. A physician will go over these medications and make adjustments to dosage accordingly. Certain medications may need to be taken at a lower dosage or even discontinued in the days prior to a colonoscopy.

Don't forget to mention any supplements—some fiber supplements may need to be stopped for a period before the test. Other common medications that may be problematic include aspirin, blood thinners, and iron supplements, so be sure to bring all these medications up to the physician doing the colonoscopy.

A Word From Verywell

There are a lot of instructions to follow before a colonoscopy. Ask questions of the doctor's office if anything is unclear. Most people have a smooth prep and colonoscopy experience and most of the time, this is due to understanding and following the doctor's orders.

While preparing for a colonoscopy is not pleasant, it's not terribly difficult and colonoscopies save lives, which is why it is important to get the test done right.

View Article Sources
  • Harvard Women's Health Watch. "Preparing for a colonoscopy." Harvard Health Publications. Nov 2008.
  • MoviPrep. "Preparing for Your Colonoscopy." Salix Pharmaceuticals. 2017.