Colonoscopy Prep Instructions

If you have an upcoming gastroenterology appointment, this page highlights how to prepare for your procedure and important contacts.

Our gastroenterology clinic is open Monday through Friday between 7:30 a.m. - 4 p.m. CT. Voicemails left after 3:30 p.m. CT may not be returned until the following business day. The GI Lab is located on the 2nd floor of the Nashville VA Medical Center.

Procedure notes

Please be prepared to stay between two and four hours for your procedure. You will be given medication for this exam and will not be allowed to drive or operate machinery for 24 hours following the procedure.

You must bring an adult with you to drive you home and may not drive yourself. Your driver must check in with you at the GI lab or your procedure may be cancelled. Your driver must stay on the premises while you are having the procedure and be available to speak with the staff regarding your discharge instructions.

If you do not have a driver, the test will be canceled unless you have made prior arrangements with the GI lab. If you arrive by VA transportation, Lyft, or Uber, you must bring a responsible adult with you, or your procedure will be canceled.

Please do not bring any valuables to your exam and please remove any jewelry, including body piercings. The GI lab is not responsible for lost or stolen items.

One week prior to colonoscopy

Eat a low-fiber diet for one week before your exam. Avoid seeds, nuts, popcorn, and other high-fiber foods.

Do not use any recreational drugs. You may take Acetaminophen (Tylenol) and aspirin if needed.

Please stop iron and fiber powder as this may affect the bowel prep for a colonoscopy.

If taking a special blood thinner, call the Anticoagulation Clinic or prescribing physician for permission to hold this medication before the procedure. These drugs include:

Clopidogrel (Plavix)
Prasugrel (Effient)
Ticagrelor (Brilinta)
Warfarin (Coumadin)
Dabigatran (Pradaxa)
Apixaban (Eliquis)
Rivaroxaban (Xarelto)
Edoxaban (Savaysa)

Each of these drugs has a different "hold" time frame, from 48-72 hours up to seven days before the procedure. If you do not hear from your physician or the Anticoagulation Clinic by seven days before the procedure, please call your primary care provider or the GI Lab at . Do not stop taking these medications without physician approval.

If you are taking diabetes medications, such as oral medications or insulin, please check with your primary care physician for guidance on how to manage them before the procedure.

Seven days before the procedure, stop taking:

Semaglutide (Ozempic, Weygovy)
Dulaglutide (Trulicity)
Terzepatide (Mounjaro, Zepbound)

These are GLP-1 medications and need to be held no less than seven days before the procedure. A common side effect of these drugs is constipation, which will prevent the colon from being properly cleaned out for the procedure. If the colon is not cleaned properly, you will need to reschedule your appointment for a different day with additional prep.

One day prior to colonoscopy

The goal during this phase is to begin getting the colon completely cleaned out. The colon is cleaned out when the stool is clear and yellow, similar to urine, and should be liquid only. It should be free of solid stool and have very few particles.

Start a clear liquid diet in the morning before the procedure. Drink plenty of clear liquids all day to stay hydrated before prepping at 6 p.m. the evening before your exam.

Absolutely no solid food the entire day before your procedure!

Clear liquid diet

Below is a list of acceptable fluids you may consume. Please do not consume clear liquids that are purple or red.

Water
Jell-O
Broth
Gatorade
Sprite
Ginger Ale
Coffee or Tea (without creamer)
Popsicles (without fruit or pulp)

Morning before the procedure

In the morning, mix the Colyte prep with one gallon of water to the fill line. You may add flavoring such as Crystal Light or other flavoring that is not red or purple.

Using a marker, place a halfway mark on the container; this divides your prep into two doses (split prep). Refrigerate if desired.

Evening before procedure

Starting at 6 p.m., start drinking your Colyte solution. Drink eight ounces every 10 minutes until half of the container is consumed. Do this over several hours. Refrigerate the remaining solution for the morning of your procedure.

Stay on a clear liquid diet for the rest of the evening.

Do not chew tobacco, gum or hard candy after midnight.

At this point, you should be using the restroom frequently. Please note what your stool looks like.

Day of procedure

You will be waking up early for this portion of your colon prep. Starting six hours before the scheduled appointment time, drink the remaining Colyte solution. Do this over several hours, like the evening before.

You must finish the solution no later than four hours before the appointment and the stool should be clear yellow by the end. If the stool is not clear, please call the GI Lab, as you may need to reschedule your appointment with additional prep.

You may have nothing else to drink starting two hours before your appointment time. Failing to follow these instructions will delay your procedure.

Do not take any insulin or diabetes medications on the day of your procedure unless otherwise instructed by your physician.

If you normally take blood pressure or any other important medications in the morning (except the ones instructed to hold), please take them no later than two hours before your procedure time.

The procedure takes from 15 to 60 minutes, but you should plan on spending two to four hours total to account for preparation, waiting, procedure, and recovery time.

Recovery typically takes between 20-45 minutes.

If you have questions about these instructions, please call the GI Lab at .

Have more questions?

Below are common questions about a colonoscopy, including definitions and risk factors.

A colonoscopy enables your doctor to examine the lining of your colon. The doctor will take a flexible tube about the size of a finger and slowly move it into the rectum and through the colon to look for signs of cancer or pre-cancerous lesions.

Often, the early stages of colon cancer do not have symptoms. That is why preventive screening is crucial. Every year, millions of adults help prevent the development of colon cancer by having a routine colonoscopy.

During a colonoscopy, doctors may find pre-cancerous growths and easily remove them. This can greatly lower the risk of developing colon cancer. Symptoms of colon cancer can include rectal bleeding, anemia, a change in bowel habits, abdominal pain, and weight loss, but these symptoms are common for other illnesses as well. When the symptoms are caused by cancer, the disease may be in a late stage.

A risk factor is anything that raises your chances of getting a disease such as cancer. Different cancers have different risk factors. Some risk factors, like smoking, can be changed. Others, like age or family history of cancer, cannot be changed.

Having a risk factor, or even many, does not mean you will get the disease. And some people who get the disease may not have any risk factors. Many lifestyle-related factors are linked to colorectal cancer. More than half of all colorectal cancers are linked to risk factors that can be changed.

Family history of colorectal cancer or adenomas (polyps)
Cigarette smoking – which can increase the risk of colon cancer death by 30% - 40%, possibly accounting for up to 12% of colon cancer fatalities
Obesity
Sedentary lifestyle
High-fat diet, especially one from mostly animal sources
Heavy alcohol intake
Ulcerative colitis or Crohn's colitis
Cancer of the uterus or ovaries before age 50
Past removal of the gallbladder
Past radiation therapy of the abdomen
Diabetes – which can increase the risk of developing colorectal cancer by 30% - 40%

The American Cancer Society recommends that adults be screened for colon cancer beginning at age 45 or earlier if there is a family history of the disease.

In general, colonoscopy is a safe procedure. As with any medical procedure, there are some risks associated with the procedure and sedation. You should contact your doctor if you feel severe abdominal pain, dizziness, fever, chills, or rectal bleeding after the colonoscopy.

Perforation and bleeding are two of the major complications associated with colonoscopy. Perforation is a tear through the wall of the bowel that may allow leakage of intestinal fluids. Perforations are generally treated with hospitalization, antibiotics, and possible surgery.

There may be bleeding at the site of a biopsy or polyp removal. Most cases of bleeding stop without treatment or can be controlled at the time of the procedure. Rarely, blood transfusions or other treatments may be required to stop the bleeding. There also is a risk of having a reaction to a sedative given during the exam. In most cases, medications are available to counteract this reaction.

Although complications after colonoscopy are rare, they can be serious and life-threatening. It is important for you to be aware of early signs that something might be wrong.

In general, most medications do not interfere with this procedure. However, if you are on insulin, your dosage may need to be adjusted – or changed – for the preparation period and the day of the exam. If you take anti-coagulant or blood-thinning medicines, they will need to be stopped and possibly started on a bridge medication before the procedure to allow for biopsy and/or polyp removal. Ask your prescribing physician about adjusting your medication.

Colonoscopy is typically not recommended in pregnant patients, patients 75 years or older, patients with limited life expectancy, or patients with severe medical problems, making them at high risk for sedation.

Common procedure questions

Have more questions about the colonoscopy procedure? View common questions and answers below.

You will receive sedation for the exam, which means that an intravenous line is placed and medications are given intravenously. This is not general anesthesia, although almost all patients are comfortable during the procedure. Because of the sedation, you will need a driver to take you home.

Preparation is a critically important part of the exam. If your bowel is not adequately cleaned before the exam, the doctor cannot identify polyps, the pre-cancerous lesions. Before the procedure, you will have to take an oral laxative solution (called “a bowel prep” or “preparation”) to clean out your bowel. Specific prep instructions vary, but the prep usually begins 1 to 2 days before your procedure. Please read your prep instructions to understand what you should do 1 day or 2 days before your colonoscopy.

Yes, the procedure can be performed while on your period. Tampons can be worn if the patient prefers to wear them.

In general, no. A colonoscopy will not be performed if a patient has a temperature over 100.0 degrees. Please contact the GI Lab and let them know as soon as possible.

The procedure itself usually takes from 15 to 60 minutes, but you should plan on spending 2 to 3 hours total to account for preparation, waiting, procedure, and recovery time.

Recovery typically takes between 20-45 minutes.

You will need to take off work the day of the procedure. Some patients who work evenings also take off work the day before the procedure to do the bowel prep.