A colonoscopy is an examination of the entire colon. In the days leading up to a colonoscopy, people will need to consume certain foods and drinks to prepare for the procedure.

A colonoscopy is a procedure that examines the colon. During a colonoscopy, a doctor uses a colonoscope, which is a narrow, flexible tool with a small light and camera at the end.

A doctor inserts the colonoscope into the rectum to provide images of the inside of the colon.

A colonoscopy can help doctors diagnose or evaluate certain conditions affecting the gastrointestinal (GI) tract, such as:

Doctors can also use a colonoscopy to help treat certain conditions, such as removing a polyp or controlling bleeding. A colonoscopy is an effective screening tool for colon cancer.

For doctors to examine the colon properly, it must be clean and clear of feces. Following a certain diet in the days leading up to a colonoscopy can help clear the bowels and allow for an effective procedure.

Learn more about the colonoscopy procedure.

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Several days before a colonoscopy, people will need to eat a diet low in fiber. Foods that are low in fiber are easier to digest, which will clear more quickly from the digestive tract and support colon cleansing.

People will need to avoid foods high in fiber, such as:

Instead, people can opt for white foods, such as white bread, pasta, and rice. People can also eat fruit without skin and canned or well-cooked vegetables without their skin.

The day before a colonoscopy, people will need to stop eating solid foods and only consume clear liquids to clear the digestive tract. People will also take a laxative to completely empty the colon.

The following table shows foods people can eat and avoid 5 days before a colonoscopy or as a doctor instructs.

Foods to eatFoods to avoid
white breadseeds or nuts
white pasta and noodlespopcorn
white riceraw vegetables with skin or seeds
potatoes without the skinbroccoli, cabbage, dried beans, corn, or peas
vegetables from a can, or well-cooked vegetables without their skin or seedsfruit with skin on
fruit from a can, or fruit without skinwholegrain bread, pasta, or noodles
tender-cooked meat, chicken, or fishbrown or wild rice
jello, but without purple, red, or blue food dyescereals such as shredded wheat, oatmeal, or granola
brothfatty foods
eggstough meat containing gristle

People will need to ask a doctor about any medications or supplements they are taking and whether they will need to stop taking these in the lead-up to a colonoscopy.

People may need to stop eating solid foods 1–3 days before a colonoscopy, depending on instructions from the healthcare professional. People will need to follow a clear liquid diet, which may include the following:

  • water
  • fat-free broth or bouillon
  • coffee or tea, with no milk or creamers
  • sports or electrolyte drinks
  • clear apple juice or white grape juice

People will need to avoid any liquids containing red, purple, or blue dyes or food colorings, as these can discolor the colon and make it harder to examine.

People will also need to avoid:

  • dairy products, including milk, smoothies, or shakes
  • orange, grapefruit, or prune juice, and any red or purple juices
  • any liquids that people are unable to see through

People will also need to take a laxative the evening before a colonoscopy. This causes diarrhea which clears out the colon in preparation for the examination.

Laxative options may include:

  • polyethylene glycol (PEG), which people may take half of the evening before a colonoscopy, and the remainder 5 hours beforehand
  • a pill, such as Dulcolax or Sutab
  • other solutions, such as MoviPrep or Clenpiq, which may suit people who do not want to drink large quantities of liquid
  • a phosphate solution, which people may split between the day before and the day of the colonoscopy

If people have any heart, kidney, or liver conditions, they will need to discuss suitable laxative options with a doctor.

Many laxatives will require people to drink around 2 liters of water to compensate for the loss of fluids with diarrhea.

In the 2 days before a colonoscopy, the Colorectal Cancer Alliance advises people to drink 8 ounces of water every waking hour to stay well-hydrated.

On the day of the colonoscopy, people will need to continue to avoid all solid foods and stick to the clear liquid diet until a few hours before the colonoscopy.

A doctor will provide instructions on how long people will need to stop drinking liquids before the procedure.

People will also need to avoid:

  • smoking
  • chewing gum
  • alcohol or drugs
  • driving a car

On the day of the colonoscopy, any stools that are clear or yellow liquid indicate that people are ready for the procedure.

People may find the following tips helpful in preparing for a colonoscopy:

  • scheduling time off or arranging for help with responsibilities so a person can be at home for their prep day
  • reducing meat intake in the few days before a colonoscopy to make proper emptying of the bowels easier
  • having easy access to a toilet for prep day, as liquid laxatives can cause forceful diarrhea and the urgent need to use the toilet
  • positioning themselves close to a toilet and keeping books, magazines, or a device with internet access to hand to occupy themselves
  • using moistened wipes instead of toilet paper, which may feel more comfortable
  • placing any moistened wipes in a bin afterward rather than flushing
  • using a soothing lotion before and during prep, which may also prevent soreness from frequent bowel movements
  • adding a flavoring to help make unpleasant-tasting laxatives taste better, such as ginger or lime
  • drinking through a straw and placing it at the back of the mouth to make it easier to swallow
  • keeping the laxative cold to improve the taste
  • sucking on a lemon or hard candy to remove the aftertaste
  • wearing loose, comfortable clothing
  • taking spare clothes or wearing adult diapers to ease discomfort when traveling, if diarrhea continues to the day of the colonoscopy
  • making sure people have a lift to and from the colonoscopy so they can avoid driving

A colonoscopy is an effective screening tool to detect precancerous or cancerous changes in the colon. It can also help diagnose or treat conditions such as inflammatory bowel disease and diverticulosis.

In the days leading up to a colonoscopy, people need to eat a low fiber diet to help the digestive tract empty more easily.

The day before a colonoscopy, people must avoid all solid foods and only drink clear liquids. People will also need to take a laxative before a colonoscopy to fully empty the colon.

People will continue a clear liquid diet on the day of the colonoscopy until a doctor instructs them to stop all liquids, which may be a few hours before the procedure.