7 Things to Avoid Before a Colonoscopy


Tests & Scans
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Table of Contents:
  1. Can I Have Chocolate Before a Colonoscopy?
  2. Can I Have a Smoothie Before a Colonoscopy?
  3. Can I Drink Alcohol Before a Colonoscopy?
  4. Why Can’t The Liquids I Drink Be Red, Purple, or Blue?
  5. Why Can’t I Have Milk Before a Colonoscopy?
  6. Should I Ask About a Split Prep?
  7. What Makes Colonoscopy Prep Drinks More Palatable? 

Colonoscopy Prep

It’s one of the most laughed about, complained about, and stressed about steps of the colonoscopy process: prep night.

While it’s nobody's favorite step, prep is necessary to clear the rectum and colon before the procedure. An incomplete bowel prep could mean missed adenomas (polyps) during a colonoscopy, while a successful prep allows for better visibility during the colonoscopy – which means doctors have a higher chance of seeing polyps, tumors, and inflammation in your colon. According to Dr. Douglas Rex from the Indiana University School of Medicine, about 40% of people who should have a colonoscopy, don’t: because of the prep!

Who needs to be screened chart

There are many types of bowel prep – with varying amounts of liquid, different flavors, and different costs. When it comes to what you can or cannot eat and drink, a lot of people get overwhelmed. So, let's answer some common prep questions to help ease your mind.

1. Can I Have Chocolate Before a Colonoscopy?

Leading up to your colonoscopy, yes, you can have chocolate! It is recommended that you follow a low-fiber diet (simply put, stay away from foods that can’t be digested as easily, such as fiber, seeds, or nuts, for example) for two to three days before your colonoscopy. This means that you can enjoy multiple forms of chocolate (solid milk chocolate or hot cocoa); however, you want to steer clear of any chocolate with nuts. The bad news is, 24 hours before your procedure, you have to stick to clear liquids, and hot chocolate is not considered a clear liquid.

2. Can I Have a Smoothie Before a Colonoscopy?

In order to have a successful colonoscopy, it is recommended to avoid smoothies for three days before your colonoscopy. You also should avoid fruits and vegetables with seeds or indigestible fiber since they are difficult to digest and may interfere with your doctor's ability to examine your colon. Examples include: 

  • Cucumbers
  • Tomatoes
  • Corn 
  • Popcorn
  • Strawberries
  • Raspberries
  • Nuts

A good rule of thumb is: If you cannot see through it, if it has pulp, or contains anything that you need to chew in order to swallow, then do not drink it. 

3. Can I Drink Alcohol Before a Colonoscopy?

According to UCLA Health, there are many reasons why you cannot drink alcohol before a colonoscopy. 

The main reason to stay away from alcohol is because it is dehydrating, and you will already be losing a lot of fluids due to the colonoscopy prep. You can avoid dehydration by drinking Gatorade (not red, purple, or blue), and other drinks with plenty of electrolytes. 

Alcohol may interact with the sedatives used during the procedure. Avoid all alcoholic beverages regardless if they are clear or not. 

4. Why Can’t The Liquids I Drink Be Red, Purple, or Blue?

Drinks that contain red, purple, or blue coloring can stain the walls of your colon. During your colonoscopy, these stains can interfere with the test and look like blood or other abnormalities. To ensure you get accurate results, physicians ask that you avoid drinks with certain coloring during your colonoscopy prep.

5. Why Can’t I Have Milk Before a Colonoscopy?

Anything that you drink other than clear liquids can end up inside of the colon. Similar to how certain dyes can affect your colonoscopy, traces of milk can hide a possible polyp in the walls of the colon. 

6. Should I Ask About a Split Prep?

If your doctor doesn’t offer a split prep, ask about it. A split prep cleansing agent is when you take half the prep the day before your colonoscopy, and the other half the day of the procedure. This type of dosing is recommended in guidelines for colonoscopy bowel prep because it tends to be more effective, and it supplies a better patient experience than a single dose.

Colonoscopy Timeline

7. What Makes Colonoscopy Prep Drinks More Palatable? 

The thought of drinking a gallon of laxative-fluids may not sound appealing or manageable. Thankfully, over the years, many different prep solutions have been created. Patients have a variety of prep solutions to choose from. You also do not have to drink the prep all in one sitting. In some cases, patients have the choice to drink the prep over two days and in smaller doses, making it much more palatable. 

According to SamHealth, an online health service, there are even cherry-flavored prep drinks that taste better than earlier versions of bowel prep solutions. 

It is important to properly prepare for a colonoscopy so that your gastroenterologist gets a good look inside your colon to accurately screen for colorectal cancer. Although a strawberry smoothie sounds great the day of your colonoscopy, drinks that contain anything that you need to chew in order to swallow are not allowed. If you are struggling to get the whole container of the solution down, try mixing your prep with something flavored, like a sports drink or powdered drink mix like Crystal light (​​no red or purple). Also, using a straw helps the prep bypass the taste buds and go down easier. 

Find whatever works best for you to make the process as smooth as possible, so it's done right the first time.

So – What Do You Think?

Many people reported at the end that when you consider the benefits of the exam, the prep “really isn’t that bad.”

More Information on Colonoscopy Prep:

33 thoughts on “7 Things to Avoid Before a Colonoscopy

  1. I have a colonoscopy scheduled for Thursday morning at 9. On Monday evening I had roast beef and a salad with raw cabbage, kale, cauliflower , etc., and pistachios. Should I reschedule?

    1. Hi Donna, We recommend you check in with the office of your provider to ask your question.

  2. I have a colonoscopy booked for this Saturday. I was sent bowel prep but asked my own doctor for a Picolax prescription, as that only requires x2 150ml of liquid to mix. I have a severe gag reflex (even struggle to hold a pen in my mouth) and even the thought of the prep made me wretch. So, last time I used Picolax, I did the following:
    Made up mixture – let it cool
    Put lemon sorbet in a bowl and poured small amount of Picolax in
    ‘Ate’ sorbet/Picolax mixture with spoon.
    I managed to take the whole 300ml without throwing up and as such, am doing the same tomorrow (but with crushed ice lollies, as no sorbet)

    1. Kristina, thank you so much for your comment and sharing what has worked for you. Lots of people avoid colonoscopies out of fear, so good for you for taking steps to make your prep work for you! We appreciate you sharing them as well! Hope all goes well with your colonoscopy on Saturday.

  3. My prep solution came from the pharmacy along with prescription anti-nausea medication that I took about 1/2 an hour before taking the prep solution. It didn’t make the solution taste any less vile, nor make the time after taking the prep any less uncomfortable, but it did keep me from nausea. Wish I’d known about using a straw though, and refrigerating the mix for a little while first to lessen the taste.

  4. Why does my provider warn, and insist I sign a waiver for potential side effects, specifically Dental and Eye Injuries!?
    Am I going to the wrong provider!? But Seriously, are Teeth and Eyes at risk, here?

    1. Good for you for going for your colonoscopy! Hmm. I wonder now if I haven’t read the risks before signing papers for my colonoscopy. You raise an interesting point.

      I don’t think you’re going to the wrong provider, they are probably just making sure all bases are covered. But I’m curious if other people have your same question!

  5. By complete coincidence, spouse & I scheduled procedures on 2 successive days! It’s actually turning out to be a good idea. Cleared our schedules, bought all the stuff, sharing the diet changes, set up bathrooms with scented candles (great idea from one of you!) etc., taking it easy, and supporting each other. BTW I haven’t seen pet care mentioned – we live in a high rise so we sent our dog to board for last 3 days, thank goodness.

    Question – I’ve read that anesthesia is optional. I’m not squeamish and I’ve thinking of doing it a la Katie Couric (she did it on film). Thoughts?

    1. Hi DeeDee, Thank you so much for your comment, and we’re so glad you and your husband had colonoscopies. You mention a good point with pet care. Thank you for sharing your tip to board. That wasn’t something any of us here thought about (and a large percentage of us have dogs). Thanks for bringing it to our attention.

      As far as anesthesia: You are a brave soul!

  6. So my experience ONLY… I have done the prescription colonoscopy prep 2 other times within the last 3 yrs. I followed to a T and nothing came out.

    So right after my 4th brain stem surgery in Jan 2021 at hospital and rehab they gave me Miralax morning and night and a pill laxative. NOTHING worked. So for 15 days after surgery I didn’t have a BM.

    Fast forward…. I figured I better get a jump on helping myself earlier. So 2 days before my Colonoscopy gave myself an Enema. Also drank 32oz Gatorade with 8oz of Miralax and nothing no BM. So the day before in morning I took 2 prescription laxatives and then 2 hr later drank 32oz Gatorade with Miralax. Then 8 hrs after 1st 2 laxative pills I took 2 more. Only had 4 small BM. Went to sleep 4 hrs woke up at at 1am to drink the other 32oz Gatorade with 4oz of Miralax. Only had 2 small BM.

    Day of – GI Doc says I’m not cleaned out good enough. So I decided I’m NOT ever doing a Colonoscopy due to 3 failed attempts. For some reason I just don’t poop like I’m supposed to hence the reason for Colonoscopy.

    1. Felicia, thank you so much for sharing your experience. Please go back to your GI and figure out with them how to get a successful colonoscopy prep and screening. If you don’t feel comfortable, then find a new GI that you do feel comfortable with.

      Tell the doctor everything you’ve said here and ask, “What do I need to do? I don’t seem to clean out and poop the way I’m supposed to.” Explain to the doctor that you don’t think you poop like you’re supposed to, but you can’t seem to clean out following prep directions exactly.

      You need to be cleaned out completely so the doctor can get the best view of your colon and rectum. Don’t give up. Keep going until you find a doctor who can help you get your successful colonoscopy. You are worth the time and effort it takes to navigate you to a successful colonoscopy.

      Please write back and tell us that you had a fourth colonoscopy attempt and that you successfully completed your colonoscopy! We look forward to hearing back from you.

  7. due to severe crohns disease I have colonoscopies a lot more often than the suggested 5yr intervals, and I have found that about 3 days before the procedure, if i go on a liquid diet and use an over the counter laxative, it will clean me out WITHOUT having to drink the horrible liquid prep solution…. my liquid diet includes nutritional drinks, jello, chicken or beef bouillon, tea and LOTS of water…. and then I begin fasting at least 24hrs before the procedure time, drinking only water to continue flushing my system out, which I stop about 12hrs before…. there is no stress to my system, taste buds or mental stress due to having to drink the prep solution… and my doctor says however im doing it, it works well….

    1. Hi Lou, We are so glad to hear that you are staying on top of your colonoscopies.

      We want to remind anyone reading to discuss colonoscopy prep with your healthcare provider so you can decide a prep that is right for you. Everyone is different, and we cannot provide medical advice.

  8. Dear Mia,
    I hope your colonoscopy prep was less of a struggle than you expected. After many colonoscopies, the prep I used for today was the easiest yet. I previously had followed lots of common tips (cold, straw, sip, chug, etc) but I think a simply lucky circumstance ended up making this prep so very effortless. Previously this summer, I spent a lot of time outdoors doing heavy garden work and, after getting heat exhaustion one day, my doctor insisted I hydrate heavily, every day, especially with an electrolyte solution. I never really liked these sport drinks before, but I started experimenting with various brands and flavors, and I gradually developed a taste for them, especially clear white Powerade and Gatorade in the uncolored cherry flavors. By the time I got to the colonoscopy in the fall, I found I actually liked them many of them, including lemon-lime. Furthermore, I had grown accustomed to drinking substantial amounts of water while working (like a gallon or more every couple of hours!).
    If your prep uses MiraLax, you will find it has no real taste or smell so it tastes the same as whatever you mix with it. I ended up dividing the Miralax (by weight, with a kitchen scale) among a couple of different flavors of sports drinks (all in the acceptable colors, of course). I would drink a glass of one or another of the various flavors over a period of 15 to 30 minutes, much in the same manner I would drink any beverage — neither chugged nor sipped very slowly. Meanwhile, I mostly cleaned house, did laundry, etc. Switching around the variety of flavors really helped (since it wasn’t so boring), as well as the fact that I was drinking a beverage whose taste I now liked. It was no problem at all getting it all down over a 3-4 hour period.
    I think the factor that made it easier than previously, to get it all out the other end, was timing. I started a low-fiber diet 4 days before the colonoscopy and a clear liquid diet the day before the day-long prep, that is two days before the colonoscopy. (My doctor wanted both the liquid diet and the prep started at 7 am the day before the colonoscopy, which was scheduled for noon the next day. This was much earlier than he had previously dictated, and I initially argued with him that I should wait until later in the day to start. I was wrong!). By evening, I was taking a walk to the library and feeling fine.
    Incidentally, someone had recommended to me that I wear a “Depends-type” underwear as soon as I finished the prep. And even though I didn’t need it, it gave me a lot of confidence that I wouldn’t have an accident.
    The diets were not fun. I normally eat a very high fiber diet and found it hard to switch to low fiber, but the many suggestions on the internet introduced me to some long-forgotten foods. The clear liquid diet left me sloshing, but not hungry. Bone broth was forbidden to me, and regular broth was tasteless and left me hungry. However I remembered from my childhood that Campbell’s canned beef consume, which is a very flavorful broth containing gelatin, will jell if placed in the refrigerator for a couple of days (or it can be eaten hot). I have never diluted it, and it is much higher calorie and satisfying than regular beef broth. It is especially delicious with a few drops of lemon juice (no pulp!) on the jello-like form.
    I hope you continue to read the internet, since there are very many good tips and comments. Search for “colonoscopy” plus whatever word you are curious about, in Google. For example, 2nd words such as: “sorbet” (OK on a clear liquid diet); “bra” (some doctors won’t let you wear one, especially if wired; others don’t care if you do or don’t); “sneezing” (you might have it if you had supplemental oxygen delivered in your nose during the colonoscopy). The world-wide-web is a glorious thing, and often 2 words will answer a question you wonder about.

  9. It’s really not so unpleasant when you change the taste, smell, and sound of the experience. Taste -> add Crystal Light and drink it icy cold from the fridge. Smell -> light some scented candles in the bathroom. Sound effects -> have loud music in the bathroom. I actually brought the vacuum cleaner in and vacuumed the baseboards while sitting there, couldn’t hear a thing.

  10. I have the same issue, unable to even think about drinking the prep without becoming nauseated. I am on a 2 week prep now, taking Miralax twice daily and a restricted diet. Tomorrow I go to a soft liquid diet for 3 days, then the full clear liquid day when I have to drink the prep. My stomach is already churning and no one seems to understand how hard this is. Some people can chug it down with no nausea. That’s not me. Every swallow is torture and does not want to stay down. They just say “do the best you can” or “it’s not that bad”. Yes, for some of us it is nearly impossible. The colonoscopy itself is easy but this prep is pure hell. I hope they find a better way to do this. My heart goes out to everyone who shares this struggle.

  11. I have Epilepsy, the instructions mention the possibility of a seizure while preparing for a colonoscopy.
    What can I do to protect myself from a seizure?

    1. Hi Zahava,
      We are so happy you are getting your colonoscopy done; however, please check with your GI or medical provider’s office to discuss epilepsy and how you can protect yourself from a seizure. Good luck! Wishing you clean colonoscopy results.

  12. I drank my first dose of Suprep 3 hours ago. It was no big deal. Tasted like salty, watered down cherry cough syrup. About 90 minutes later, it started working. Honestly, it was fine. Very little effort involved. I think I’m about done. Then I’ll do it all over again at 4:45am.
    This is so much less horrible than I thought. I’m really glad I didn’t put it off for the third time.

    1. Hi Jen, Thank you so much for your response to this blog. Not only are we so glad to see that you are getting this done — and that you didn’t put it off a third time — we are thrilled that you shared your experience for others to see that while prep is no joy, it is “much less horrible” than you thought. Your words will inspire others to “not put it off.” Thank you so much! Wishing you a clean colonoscopy and good news!

  13. My colorectal surgeon went to split dose this year and I have concerns. In the past (and I do this yearly), I am up every 30-45 minutes until about 3 am. Now I am supposed to get up at 3:20 am (5 hrs before the procedure) and drink 32 Oz of Miralax in the next hour. Then, presumably, I’ll be pooping until I have to go to the surgical center (leave home about 6:30); and maybe on the way into a Depends – ugh!). I am 72 and not in great health so the thought of a medical procedure on so little sleep is worrisome.

    1. We completely understand your concerns. Please speak with your GI or a nurse or staff from his office who can help you through this. They will be better able to address your concerns and perhaps be able to work with you for a solution that you are comfortable with.

    1. Hi Anne!

      Thanks for your comment! We advise, “In order to have a successful colonoscopy, it is recommended to avoid smoothies for three days before your colonoscopy. You also should avoid fruits and vegetables with seeds or indigestible fiber since they are difficult to digest and may interfere with your doctor’s ability to examine your colon.”

      In the case of conflicting information, we recommend you check with your gastroenterologist’s office to verify that you are following their prep. The ultimate goal is that your doctor has the cleanest and clearest view possible during your colonoscopy. Good luck!

  14. It’s really not that bad during prepping. Exclude heavy meats and fried food the week before. 3 days before stick to eggs and white bread toast, the day before no food! Also- my dr had me take 2 laxatives three days before, then 2 days before I drank magnesium citrate, then the day before I drank another magnesium citrate, then 7 doses of Miralax (on ice, with a straw, I’d drink about 6-8 oz then stop for 15 minutes then drink another 6-8oz, then rest for 15 minutes. THEN six hours later I drank another 7 doses of Miralax AGAIN.). All in all, do no eat the day before, take it slow while ingesting your mixture, rest in between sips if needed, and buy a bucket of Vaseline & baby wipes & soft tissue paper. And have a good reading book handy. Stay on a couch or bed the day before close to a potty. It’ll be fine! Trust me. I birthed 5 kids, prepping for a colonoscopy is a cake walk.

    1. Thank you so much for sharing your prep experience with us! We are so happy that you had a successful prep and colonoscopy!
      Great tip about drinking with a straw, and breaking your drinks into 15 minute increments! That makes the 32 oz seem so much less overwhelming.
      We do not provide medical advice, so we recommend everyone follow the colonoscopy instructions provided by their medical providers as they may vary, and if they have questions to ask their medical provider’s office.
      Thanks again for sharing your positive experience!

  15. My instructions are to follow the restricted diet for FIVE days. I am worried that I will become sick from not eating the foods that my body is used to for that long.

    1. Hi Al,
      Thank you for your comment. Have you discussed your concerns with your doctor or GI? We are not able to provide medical advice, so we recommend that you speak with your doctor so that you are able to have a complete and successful colonoscopy.

  16. It really doesn’t matter how good the prep liquid tastes going down. What matters is the prep experience itself, and that will still be very unpleasant.

    1. I have to disagree. If the prep were not nauseating, I would be better able to achieve a good result for the test.

  17. I’m a 9 year stage 3 rectal cancer survivor. I’ve had more colonoscopies than I care to think about. I dread them like the plague due entirely to the taste of the prep! In my wildest dreams, I couldn’t imagine anyone coming to rescue me from the awful, sickening flavor of the various prep solutions I’ve had! I hope these will be a solution!!!

  18. I have now done various preps for 17 years, and over time I had become less and less able to prep adequately because of nausea, which now approaches even when I think about this. While forcing the stuff down, in deep misery, I remember weeping, desperately, and wishing to die. My strategy has been to start the liquid diet four days before the procedure and, at the same time, to begin a Miralax regimen. Then last time my doctor tried something called Prepopik, which was not so vile. My fear is that I will develop an inability to swallow Prepopik. I would welcome any advice or suggestions.

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