Colonoscopy: Prep, Diet, Side Effects & Complications (2023)

This page was reviewed under our medical and editorial policy by

Bradford Tan, MD, Chair, CTCA Department of Pathology and Laboratory Medicine.

This page was reviewed on November 15, 2021.

A colonoscopy is considered the gold standard for detecting colon and rectal cancers early—sometimes even before they become cancers. As many as nine out of every 10 people whose colorectal cancersare found early and treated appropriately are still alive five years later, according to the U.S. Centers for Disease Control and Prevention.

Why do I need a screening colonoscopy?

The American Cancer Society recommends that people who are at average risk for colorectal cancer start regular screening at age 45, with a colonoscopy exam (or stool test). Other organizations suggest starting such screening at age 50 if you are at average risk.

Average risk for colorectal cancer means that you don’t have a:

  • Personal or family history of colorectal cancer or certain types of precancerous polyps
  • Personal history of inflammatory bowel disease
  • Genetic syndrome that predisposes you to colon cancer
  • History of radiationto the abdomen or pelvic area to treat a prior cancer

If you’re at an increased risk for colon cancer, you may need to start screening earlier and take other precautions. Other reasons your doctor may suggest a colonoscopy include unexplained changes in bathroom habits, abdominal pain or unexplained weight loss. In these instances, the colonoscopy is considered diagnostic and isn’t a screening tool.

(Video) Digestive health: Successful prep for colonoscopy

How do I prepare for a colonoscopy?

Prepping requires a thorough cleansing of the colon so little or no stool remains. If there is stool, your doctor can’t see the lining of your colon, and you may need to repeat the test (and the prep).

  • Low-fiber diet: Research has shown that limiting your diet for several days prior to having a colonoscopy achieves better results. You may be required to avoid fiber-rich foods (including certain fruits and vegetables, seeds, popcorn and whole grains), and instead consume only low-fiber, refined foods that are easily digested.
  • Clear liquid diet: Prep will likely start with a clear liquid diet (broth, lemon or lime gelatin, sports drinks, tea, apple or white grape juice, water) for one to three days before the procedure. It’s important to avoid red- and purple-colored drinks or gelatin, as these can look like blood during your colonoscopy.
  • Adjust medications and supplements as directed: Some medications, including non-steroidal anti-inflammatory drugs (NSAIDs), can increase risk of bleeding or may interfere with the procedure, so make sure to let your doctor know which over-the-counter remedies, vitamins and supplements you’re taking.
  • Bowel cleansing protocol: You’ll also need to take a combination of laxatives, most often on the night before and the morning of the procedure. They can be mixed with clear liquid and/or taken as pills, and they work by loosening stool and increasing bowel movements.
  • Enema kit: Your doctor may also prescribe an enema, which is a liquid or gas that is flushed into your anus to clean out stool.

During prep days, expect diarrhea and stay close to a bathroom. How can you tell if you prepped correctly? You should be passing liquid that is clear enough to see through. Make sure to drink enough fluids during bowel prep to avoid dehydration.

(Video) What happens during and after a colonoscopy?

What can I expect during a colonoscopy?

A colonoscopy typically takes about 30 to 60 minutes, depending on if the doctor needs to remove any polyps or take biopsies. Patients should expect to be at the facility for up to three hours to ensure adequate prep and recovery.

  • During the procedure, the doctor inserts a colonoscope (a thin, flexible, lighted tube with a lens and a scraper tool for removing tissue) through the anus into the rectum and colon.
  • Air is pumped into the colon to expand its circumference and allow for a better view of its lining.
  • You may receive general anesthesia (asleep) or conscious sedation (awake, but not fully aware) during the colonoscopy. If polyps are discovered, your doctor may remove them at this time. If any abnormal tissue is found, a biopsy may also be taken.
  • Though you won’t feel pain during the procedure, you may experience bloating and cramping in your abdominal area for about an hour after your colonoscopy.

Your doctor will discuss anesthesia options in advance of the procedure. These medicines are usually given intravenously, along with pain medication. A doctor, nurse or another member of the health care team will check your vital signs and make sure you are as comfortable as possible during the entire procedure.

If your doctor sees any abnormal or possibly precancerous or cancerous growths, they typically remove them during the colonoscopy. These precancerous polypscan grow for years and change into cancer without causing any symptoms.

What kind of doctor performs a colonoscopy?

A gastroenterologist who has been specially trained in the procedure will perform your colonoscopy.

(Video) My Colonoscopy experience "NEVER AGAIN"

  • Guidelines outlined by the American Society for Gastrointestinal Endoscopy recommend that any doctor who performs a colonoscopy should have completed a gastroenterology fellowship or surgical residency program.
  • Additionally, according to the American College of Gastroenterology, the gastroenterologist should have a perforation rate of less than one in 500 colonoscopies—this is the rate at which the doctor has created a hole in the colon in error during the procedure.
  • Having a board-certified gastroenterologist perform the procedure is highly recommended, as they complete even more colonoscopy training and must take ongoing medical education classes.

What happens after the colonoscopy procedure?

Your doctor will let you know how it went and whether any polyps were found or removed and sent off to a lab for a biopsy. It may take a few days to get these results, which will guide the next steps.

Typically, patients are groggy after a colonoscopy. This is because it takes time for the anesthesia to fully wear off, and you'll need someone to drive you home. During recovery, you may be offered something to drink and/or eat. It’s normal to feel bloated and gassy after the procedure. You’ll also be encouraged to pass gas to remove any of the bloating. Typically, patients can resume eating normally the next day unless the doctor advises otherwise.

Colonoscopy recovery and side effects

Typically, patients are groggy after a colonoscopy because it takes time for the anesthesia to fully wear off. That means you'll need someone to drive you home. Plan to stay at the facility for one to two hours after your colonoscopy. During recovery, you may be offered something to drink and/or eat. It’s normal to feel bloated and gassy after the procedure; abdominal cramping may also occur. You’ll be encouraged to pass gas to help reduce bloating. You may pass liquid and/or liquid stool after your colonoscopy but, within one to five days, your bowel movements should return to normal. If you’ve had a biopsy, it’s normal to experience anal bleeding or bloody stool after the procedure. Delayed bleeding may also occur for up to two weeks afterward.

What can I eat after a colonoscopy?

Typically, patients may resume eating normally the next day unless the doctor advises otherwise. After the procedure, it’s recommended that you start with light meals, gradually introducing solid foods on the first day. It may be helpful to stick with bland, low-fiber foods for 24 hours after your colonoscopy.

For example, safe foods may include:

  • Milk and low-fat dairy
  • Cooked vegetables
  • Potatoes
  • Canned fruit and applesauce
  • Bananas, melons
  • Fruit and vegetable juices
  • Breads, cereals, pastas and crackers (not whole grain)
  • Pudding and gelatin
  • Eggs
  • Graham crackers
  • Broth
  • Weak tea

It may be helpful to avoid these foods the day of your procedure:

  • Foods high in fat
  • Hard and blue cheeses
  • Raw vegetables
  • Dried fruits
  • Whole grain breads, cereals, pastas and crackers
  • Spicy, fried or fermented foods
  • High-sugar foods
  • Nuts and seeds
  • Cured meats and fish
  • Alcohol and caffeine
(Video) Common Complications After Colonoscopy

Colonoscopy complications and risks

A colonoscopy is considered a safe and life-saving procedure, but like with all medical procedures, it’s not without risks. Some of the most common risks include:

  • Bleeding, especially if polyps are removed or a biopsy is performed
  • Delayed bleeding up to two weeks after the colonoscopy
  • A reaction to the anesthesia

Another risk—and one that is feared—is a perforation or hole through the wall of the colon. It's important to know the risk of a perforated colon is extremely low. The care team will review all possible risks with you before the procedure.

(Video) Endoscopy + Colonoscopy Experience | Sutab | Prep and Procedure


What is the most common complication after colonoscopy? ›

Bleeding is one of the most common complications of colonoscopy, accounting for 0.3-6.1% of cases[35,36].

What are two potential problems after a colonoscopy? ›

Complications related to colonoscopy include, but are not limited to, the following: Continued bleeding after biopsy (tissue sample) or polyp removal. Nausea, vomiting, bloating or rectal irritation caused by the procedure or by the preparatory bowel cleansing.

How long do colonoscopy prep side effects last? ›

You may experience several minor effects including, but not limited to: You will be tired for the day and may feel confused or forgetful. This may last up to 12 hours after sedation and should resolve after a full night's rest. You may not recall speaking with the doctor after the procedure.

Does colonoscopy Prep cause inflammation? ›

Another possible mechanism is that certain bowel preparation agents, including those containing sodium phosphate, can promote inflammation [14], metabolic changes [15], and ulcerative abnormalities [16, 17] in colonic mucosa.

How long does it take to fully recover from a colonoscopy? ›

The First Week after a Colonoscopy

After polyps are removed it can take up to a week for the patient to fully recover. During this time, patients should avoid all strenuous activities, which includes lifting anything over five pounds.

What should you not do after a colonoscopy? ›

Colonoscopy Recovery: After the Procedure

The effects of the sedation could last up to a day, so you should not drive or operate any machinery until the following day. You may feel gassy or bloated for a while after the procedure because of the air that was injected into your intestine during the colonoscopy.

What are some of the dangers having colonoscopy? ›

Risks and Serious Complications
  • Bleeding: If a tissue sample is taken, you may notice some bleeding from your rectum for a day or two after the procedure. ...
  • Infection: Bacterial infections have been known to occur after a colonoscopy.
10 Oct 2021

What percent of colonoscopies have complications? ›

However, as with any medical procedure, complications are possible (although rare). Studies estimate the overall risk of complications for routine colonoscopy to be low, about 1.6%.

Can a colonoscopy damage your colon? ›

Rarely, complications of a colonoscopy may include: A reaction to the sedative used during the exam. Bleeding from the site where a tissue sample (biopsy) was taken or a polyp or other abnormal tissue was removed. A tear in the colon or rectum wall (perforation)

Can you get sick from colonoscopy prep? ›

Side effects of some preps include nausea, abdominal pain, bloating, vomiting, thirst, dizziness, and dehydration. If you feel nauseous or vomit, take a 30 minute break, rinse your mouth, and then continue drinking your prep.

What is a good first meal after a colonoscopy? ›

After a colonoscopy, eat foods that are soft and easy to digest to ease side effects such as bloating or gas. This may include eggs, white toast, and applesauce for breakfast. For lunch or dinner, choices could include lean chicken without skin, mashed potatoes, and soft-cooked carrots.

Can colonoscopy prep cause kidney problems? ›

Before a colonoscopy, it is critical to completely empty all stools from the colon, but some patients have experienced a rare, but dangerous issue with kidney problems after colonoscopy prep.

Can a colonoscopy prep cause heart problems? ›

5 In high-risk patients, there have been cases of cardiac arrhythmias triggered by bowel prep for colonoscopies; these patients had other comorbidities, including renal insufficiency, concurrent use of diuretics, or advanced age.

Can you have an allergic reaction to colonoscopy prep? ›

Suprep Bowel Prep Kit side effects

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

How soon after colonoscopy can you eat? ›

Your doctor may recommend that you eat sparingly, or not at all, in the hours immediately following the procedure. For the rest of that day and the day after, you'll be advised to drink lots of fluid and to eat soft, easily digestible foods which won't irritate your colon.

Should you rest the day after a colonoscopy? ›

Colonoscopy recovery is usually quick with most people resuming normal activity the next day. Even so, it is important not to rush back to work. It is best to take the remainder of the day to rest, recover from sedation, and replenish fluids and nutrition. The results of your exam should be available within a few days.

Should you take off work the day after a colonoscopy? ›

Take the day off: It is recommended that you take the day off work on the day of your procedure. You should not make any important decisions for the rest of the day following the procedure. You should not drive for the rest of the day. Pick up your prep at least three to five days before your procedure.

How do I rebuild my gut after a colonoscopy? ›

Here are a few steps that you can take to gently and naturally replenish your gut flora through probiotics:
  1. Eat yogurt and kefir that is high in probiotics for several days after your colonoscopy. ...
  2. Take a probiotic supplement in the morning on an empty stomach. ...
  3. Eat a diet rich in prebiotics.
19 Oct 2015

How do you settle your stomach after a colonoscopy? ›

Have foods that are easy to digest, such as soup, crackers, toast, chicken, fish or cooked vegetables. Do not eat foods that may cause bloating and gas, such as beans, onions, garlic, cabbage, broccoli, cauliflower, chocolate or spicy foods. You can start eating regular foods the next day.

Who should avoid colonoscopy? ›

Because colon cancer grows slowly, colonoscopies aren't always recommended for people who are older than 75 and have medical problems that put them at higher risk for complications. The bowel prep used can sometimes be of concern for seniors because it can lead to dehydration or electrolyte imbalance.

Can a colonoscopy do more harm than good? ›

This means many people are at unnecessary risk of harm from potential colonoscopy complications such as bleeding, perforated bowels, and even death. Very old patients are at increased risk of serious side effects (and are among the least likely to benefit from screening colonoscopies).

Can you get pancreatitis from having a colonoscopy? ›

Although uncommon, the present case illustrates that it is possible for a patient without pre-existing risk factors to develop pancreatitis following colonoscopy. We suspect that difficulty in advancing a colonoscope past the splenic flexure may result in trauma to the pancreas.

Is colonoscopy worth the risk? ›

The study found only meager benefits for the group of people invited to get the procedure: an 18% lower risk of getting colorectal cancer, and no significant reduction in the risk of cancer death.

Is there an alternative to a colonoscopy? ›

Colonoscopy is one method of screening for colorectal cancer. Other methods are also effective and available. Alternatives to colonoscopy include sigmoidoscopy, which is a less invasive form of colonoscopy, and noninvasive methods, such as stool sample testing.

How common is pancreatitis after colonoscopy? ›

Abdominal pain after colonoscopy is a relatively common symptom and usually benign. Colonoscopy-induced pancreatitis is an extremely rare phenomenon that can sometimes be missed leading to delayed diagnosis and treatment.

How do you know if your colon is messed up? ›

  • A persistent change in your bowel habits, including diarrhea or constipation or a change in the consistency of your stool.
  • Rectal bleeding or blood in your stool.
  • Persistent abdominal discomfort, such as cramps, gas or pain.
  • A feeling that your bowel doesn't empty completely.
  • Weakness or fatigue.
8 Oct 2022

How do I know if I have a perforated colon? ›

The primary symptoms of gastrointestinal perforation are severe abdominal pain and tenderness. The abdomen may also protrude or feel hard to the touch. If the hole is in a person's stomach or small intestine, the onset of pain is usually sudden, but if the hole is in the large bowel, the pain may come on gradually.

Can colonoscopy cause diverticulitis? ›

Although colonoscopy-induced diverticulitis is a rare finding, it is important to consider it as a complication in patients with symptoms after colonoscopy. Potential causes of post-colonoscopy diverticulitis include barotrauma, multiple attempts for intubation, and direct pressure of the scope.

How much weight is lost prepping for colonoscopy? ›

A loss of around 3 pounds. The fasting experience wasn't too bad. The water, broth, Jell-O, and laxatives actually made me feel pretty full so I didn't have any real hunger pangs but I did miss being able to indulge when I wanted. I was hungry the morning of the procedure but it wasn't unbearable.

Will I be up all night after colonoscopy prep? ›

Will I be up all night with colonoscopy prep? Probably not, if you start on time. While everyone's body is different, most people are able to complete their round of purging before going to sleep for the night.

Is it normal to feel weak after colonoscopy prep? ›

As you begin taking your oral laxative, you'll experience the frequent urge to empty your bowels—this can lead to dehydration and/or drops in blood sugar that may cause you to feel nauseous, dizzy, lightheaded, and/or thirsty.

What activities can I do after a colonoscopy? ›

Activity: You should not drive a vehicle or perform strenuous activities on the afternoon or evening following colonoscopy. Unless you have had a polypectomy, you should be able to resume all normal activities the day after your colonoscopy. If you have any doubts about resuming an activity, call your doctor.

What foods are easy to digest before a colonoscopy? ›

Doctors recommend low-fiber foods that are easy to digest and leave your system quickly. You can have: White bread, pasta, and rice. Well-cooked vegetables without skin.
Don't eat:
  • Seeds, nuts, or popcorn.
  • Fatty foods.
  • Tough meat.
  • Whole grains.
  • Raw vegetables.
  • Fruit with seeds or peel.
  • Corn, broccoli, cabbage, beans, or peas.
14 Feb 2021

Can you eat tuna fish after a colonoscopy? ›

Try to stick with lean protein instead of high-fat meat for the first day or so after your colonoscopy. While meat is a great source of protein, high-fat meat is more difficult to digest than softer, leaner protein like tuna, fish, or eggs.

Why do I still have diarrhea after colonoscopy? ›

Although your stool testing and colonoscopy have been negative, there are many possible causes of diarrhea that have not been excluded. Among these are such things as: Irritable bowel syndrome. Some people with irritable bowel syndrome have a type that is called "diarrhea predominant." Stress can worsen symptoms.

Can colon PrEP cause gallbladder problems? ›

The relative dehydration caused by bowel preparation may make the patients more susceptible to developing acute cholecystitis. Dehydration caused by bowel preparation may lead to bile stasis, increased bile lithogenicity, and gallbladder distention, which increase the risk of a local inflammatory reaction [4].

Can colonoscopy PrEP cause electrolyte imbalance? ›

Colonoscopy is a useful tool in modern medicine and is increasingly employed for both diagnostic and treatment purposes. However, bowel preparations can cause electrolyte imbalance, with the risk apparently related to the type of bowel cleansing solution used, the age of the patient and their comorbidities.

Can a colon cleanse cause kidney problems? ›

Side effects of colon cleansing include nausea, vomiting, diarrhea, dizziness, dehydration, electrolyte abnormalities, acute kidney insufficiency, pancreatitis, bowel perforation, heart failure, and infection.

Can the prep for a colonoscopy cause AFIB? ›

Results: We identified 16 patients with new-onset SVT after ingestion of bowel preparation solution before undergoing the colonoscopy procedure. In all, 12 (75%) patients developed atrial fibrillation, 3 (18.8%) patients developed atrial tachycardia, and 1 patient (6.3%) developed atrial flutter.

Is your heart monitored during a colonoscopy? ›

Your nurse will monitor your blood pressure, heart rate and oxygen. If these levels are good and you need more medication, your nurse will give it to you. You may have cramps and feel some pressure as the scope moves through your colon.

Can you get endocarditis from a colonoscopy? ›

E faecalis endocarditis may occur on native aortic valve after colonoscopy in patients with Heyde's syndrome. Thus, appropriate antibiotic prophylaxis should be considered in patients with suspected Heyde's syndrome undergoing colonoscopy.

How do I keep my blood sugar stable during colonoscopy prep? ›

If you have a low sugar during nothing by mouth time, use glucose tablets. Replace usual meals with 45-60 grams of liquid carbohydrate or 1 ½ cups to 2 cups. Liquid carbohydrate is absorbed in the stomach more rapidly and could increase the chance of low blood sugar.

What happens if you start your colonoscopy prep too early? ›

We ask that you start the bowel prep at the time we gave you. But if you do start one or two hours earlier or later than the time given you, that's fine as long as you follow the clear liquid diet for the day.

How do you know if something is wrong after a colonoscopy? ›

Post-Colonoscopy Complications

Call your doctor right away if you have any of these symptoms after your test: Severe pain or cramping in your belly. A hard belly. Trouble passing gas or pooping.

How long after colonoscopy can complications arise? ›

Most colonoscopy adverse events occur within 7 days, but even more occur beyond the 7-day period.

What are the signs of a perforated bowel after colonoscopy? ›

How Do You know if You Suffered a Perforation?
  • Pain in the abdomen, which can be severe.
  • Chills.
  • Nausea.
  • Vomiting.
  • Fever.
  • Bleeding from the rectum.
5 Mar 2020

How common are complications from colonoscopy? ›

On the other hand, the American Society for Gastrointestinal Endoscopy says that there are less than 3 serious complications for every 1,000 procedures done in people of average risk for colorectal cancer.

Can a doctor tell if polyp is cancerous during colonoscopy? ›

Most polyps are benign (not cancerous). Your doctor can tell if a colon polyp is cancerous during a colonoscopy by collecting tissue to biopsy. The results of the biopsy are typically sent to your doctor within a week. Only 5% to 10% of all polyps become cancerous.

What percentage of colonoscopies result in perforation? ›

One of the most serious complications of colonoscopy is endoscopic perforation of the colon, which has been reported as between 0.03% and 0.7% [1, 2].

How long after a colonoscopy can you get a perforated bowel? ›

Although perforations usually occur during the colonoscopic examination or within 24 h after the procedure[1-3], delayed perforation of the colon and rectum has been reported[38,39].

Can you have a perforated bowel and not know it? ›

The signs and symptoms of a perforated GI tract come on gradually, getting worse, although they might not be too noticeable at first. They may include: Severe stomach pain. Chills.

What to watch for after a colonoscopy? ›

If you have any of the following symptoms after a colonoscopy, seek medical care right away:
  • severe pain in your abdomen.
  • fever.
  • bloody bowel movements that do not get better.
  • bleeding from the anus that does not stop.
  • dizziness.
  • weakness.


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