Clear liquid diets are usually used in combination with medication that causes diarrhea (bowel prep). The bowel prep is a very strong laxative which causes diarrhea and removes solid stool from the colon. The clear liquid diet allows you to avoid dehydration without creating more solid stool after taking the bowel prep. This should begin in the morning of the day before the colonoscopy.

Clear liquids have two main characteristics; you should be able to see through the liquid and, at room temperature, nothing remains on a fork lifting the clear liquid. Acceptable liquids are water, sodas, popsicles, juices (without pulp), soups (broth only), and Jello (no fruit).

Fleets® enemas are used to clean the stool from the last third of the colon. This is usually necessary for limited endoscopic examinations of the anus (anoscopy), rectum (proctoscopy), and sigmoid colon (flexible sigmoidoscopy). It is also necessary for many surgical procedures performed in the anal area.

The preparation involves taking two enemas. Some doctors suggest both enemas be taken at the same time, within two hours of the procedure. Other doctors suggest one enema be taken the evening before the procedure, and the second enema be taken within two hours of the procedure. Instructions for enema use are provided on the package or online.

This type of bowel prep uses one gallon of a special salt solution to clean the bowel. This is used to prepare the colon for colonoscopy or surgery. The gallon is finished over 4 hours (4-8 pm, the night before a procedure) by drinking an 8 ounce glass every 10 minutes until the gallon is finished. The large volume of liquid is not absorbed by the intestine. Instead, it completely passes through the intestine, causing diarrhea. This prep is the safest type of prep for elderly patients, or those who have heart failure, kidney failure, or are prone to electrolyte problems. Some people find it helpful to drink the solution chilled and with a straw placed far back in the mouth, to minimize the taste.

This type of bowel prep uses a small volume of a liquid medicine to cause diarrhea. The majority of the fluid that makes the stool watery is secreted into the colon from the body or fluid which has been drunk during the prep. This is used to prepare the colon for colonoscopy or surgery.

The Fleets® Phospho-soda® is taken in two doses. If it is being used before surgery, the two doses are taken late in the afternoon before surgery, about two hours apart. If it is being used before colonoscopy, the two doses are taken on two separate days. The first dose is usually taken the day before the colonoscopy (in the late afternoon or early evening). The second dose is usually taken the morning of the colonoscopy (at least three hours before having to leave the house for the appointment). Each dose is 1½ ounces (3 tablespoons). It is best taken by mixing one tablespoon in eight ounces of a flavorful clear liquid (apple juice, ginger ale, etc.) every 10 minutes. In this way, the entire dose is diluted but still consumed over 20 minutes. It is important to continue to drink plenty of clear liquids after finishing the full dose. This helps to make sure the colon is cleared from stool and avoid dehydration.

This type of bowel prep uses a tablet version of the same medicine as the Fleets® Phospho-soda® prep to cause diarrhea. This is used to prepare the colon for colonoscopy. The majority of the fluid that makes the stool watery is secreted into the colon from the body or fluid which has been drunk during the prep.

The Visicol® tablets are taken in two doses. The first dose is usually taken the day before the colonoscopy (in the late afternoon or early evening). The second dose is usually taken the morning of the colonoscopy (at least three hours before having to leave the house for the appointment). Each dose is 20 tablets. It is best taken by swallowing 3 tablets with eight ounces of a clear liquid every 15 minutes. It is important to continue to drink plenty of clear liquids after finishing the full dose. This helps to make sure the colon is cleared from stool and avoid dehydration. Some doctors are now using fewer tablets for the second dose on the morning of the colonoscopy, usually between 8 and 12 tablets.