Ask almost anyone after their first colonoscopy, and they’ll tell you, “The procedure was nothing, but the prep was awful.”

Now patients are reporting that combining MiraLAX®, an over-the-counter laxative, with 2 quarts of Gatorade tastes better and is easier to take than the standard 4-quart Golytely colonoscopy preparation. In a randomized clinical trial , almost 100 percent said they would repeat it again, compared to 1 out of 4 who wouldn’t take GoLYTELY® in the future.

In addition, doctors found no differences in how thoroughly the two preps clean the colon.

Splitting the dose between the night before the colonoscopy and the morning of the procedure did improve colon cleansing. But there was no difference in cleansing between split-dose GoLYTELY and split-dose MiraLAX with Gatorade.

Although the combination of MiraLAX and Gatorade is being used to clean the colon before colonoscopy by community gastroenterologists, there hasn’t been evidence that it was safe and effective. Gastroenterologists at the VA Healthcare System in Long Beach, California and at the University of California Irvine developed a randomized clinical trial to compare the MiraLAX prep with traditional  GoLYTELY.

They also compared bowel cleansing quality between giving all of the dose the night before colonoscopy to splitting the dose between the evening before and the morning of the exam.


  • There was no difference in bowel cleansing between the GoLYTELY and the MiraLAX/Gatorade preps.
  • There was a significant difference in bowel cleansing when either prep was given in a split dose. Split doses were better.
  • On a questionnaire, patients reported better taste and tolerability for the MiraLAX prep.
  • 96.8 percent of patients said they would be willing to repeat the MiraLAX prep compared to 75 percent of the GoLYTELY patients.
  • There were no significant changes in electrolytes before and after the prep between MiraLAX and GoLYTELY or in single-dose or split doses.

GoLYTELY is a powdered form of polyethylene glycol (PEG-ES) and electrolytes. It is combined with about a gallon of water to draw fluid into the colon to flush out feces.

MiraLAX is also powdered PEG, but doesn’t contain electrolytes. It needs to be combined with two quarts of Gatorade to replace the electrolytes lost in watery diarrhea during the prep process.

Jason B Samarasena MD and his colleagues concluded,

Split-dosed MiraLAX/Gatorade was an effective, safe, and tolerable option for bowel preparation before colonoscopy in the low-risk patients in this study. MiraLAX/Gatorade appears to be more tolerable than Golytely as a bowel cleansing regimen and was the preferred agent by the patients in this study.

What This Means for Patients

Ask your gastroenterologist about combining MiraLAX with Gatorade as a preparation for colonoscopy.

Splitting the prep in two doses: one the evening before your test and the other half the morning before the exam will improve colon cleansing. A clean colon is critical to an accurate exam.

Source: Samarasena et al, The American Journal of Gastroenterology, advance online publication May 8, 2012.

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10 comments on “Have They Found a Better Colonoscopy Prep?”

  1. 1
    Karen F. on August 6, 2019

    I will be having my 60 yr birthday present at 12noon today. I guarantee you I will NOT accept this gallon of PEG for my 70th Birthday!! My first colonoscopy (my reward for turning 50) was huge salty pills followed by a glass of water. Unpleasant but doable. A gallon of PEG (Split Dose) is well, in my mind, totally unacceptable. The nausea is awful. I just dumped the last 20 ounces down the drain. Can’t and wont do it! Wish I knew about the Mirlax and Gatorade option before this. Come on people ….this is 2019 we have to have a better solution (pun intended). I’ll let you know how it goes but there is no way I am repeating this for my 70th!

  2. 2
    Elizabeth Allerton on April 28, 2019

    I have teo colonoscopy both times I was deathly sick and very weak being on this prep to the point of complete dehydration almost passing out.

  3. 3
    Trish on April 27, 2019

    Virginia – I just had the Suprep yesterday before my first colonoscopy. I could get the “day before” dose down ok, and had no cramping or pain of any kind. It almost was painless, really. The bigger problem was trying to tolerate and “keep down” the next dose the morning of my procedure. On an empty stomach, with that BITTER taste (even mixed with Crystal light lemonade)I could only get about 85-90% of it down–however I was “clear” the night before so I suspected I was “good” – dr. confirmed I was the next day. One small polyp removed, awaiting biopsy results. I may look at Miralax next time if it has no taste…I’d rather taste 64 oz of Gatorade then taste that Suprep again!!

  4. 4
    Virginia on March 13, 2019

    Has anyone’s doctor ordered you to use SUPREP To cleanse for Colonoscopy? It was by far
    the worst prep I’ve ever had to do. I”m 76, so have had several Colonoscopies. It was a night
    from hell from 6pm to 11:00, I had cramps worse than labor pains and then my bottom felt like fire was coming out and burned horribly til I couldn’t even wipe, just hurt so bad to even blot myself in between blasts! It tasted awful and then coming out even worse!

  5. 5
    Denny Vass on March 13, 2019

    Why not mix the GoLytley with Gatorade instead of water? I’ve had a problem getting a thorough cleanse with the miralax/Gatorade mix in the past and also had a problem with keeping down the GoLytley/water mix. Would there be a problem with that solution?

  6. 6
    Frank simons on February 13, 2018

    Miralax was a total failure for my recent colonoscopy. I followed directions given me by my doctor, however it was far from cleansing the bowel for the procedure…therefore it was a failure.
    My doctor concluded, “poor preparation “. I don’t get it.
    A successful colonoscopy is critical in my situation because of copious bleeding. I’ll need another colonoscopy but I ask myself, do I need to find another doctor?

  7. 7
    Cynthia Wall on October 21, 2016

    Tomorrow I have my appointment for my colonoscopy. I’ve been dreading drinking the GoLYTELY Prep. Since last time I had an epic failure, I couldn’t drink all the prep. So I had to cancel my appointment. While drinking it was causing me to gag, so I just couldn’t drink it. It was a supposed piña colada flavored one, or not!! Ugh horrible experience!!

    I first said a prayer asking God to help me be able to drink this without any problems. So I can have my procedure done tomorrow, since it’s important. I made sure to chilled the prep longer this time, this is a lemon flavored prep this time. I picked up some orange spiced herbal tea, brewed a cup and poured 8oz of prep into a separate glass.

    Any way… I drank a few sips of my hot orange spiced herbal tea first, then used a straw and drank down my first 8oz glass of prep. I’ve already managed to drink 2-8oz glasses of prep in the first half an hour. I didn’t gag once during drinking it. I made sure to use a straw so I can avoid the prep hitting my taste buds. Between the straw, smell and after taste of the orange spiced herbal tea, it seems to block the taste and smell of the prep. All I’m tasting is the tea. I also make sure to suck it all down each time as fast as I can. So no stopping during drinking it.

    I’m finding that doing all of the above is actually making this a whole lot easier.

    I hope this helps other people, I know it’s making it easier for me to get through this. I have to give credit to someone else who had mentioned drinking orange spiced herbal tea before and after each glass of prep. I had read that on line.

    Best to everyone, we all have to go through this sooner or later. But if we can do it in an easier way then I’m all for it. God bless everyone!! <3

  8. 8
    Debbie on April 2, 2016

    Nobody’s going to die or become obese from drinking Gatorade one in 5 or 10 years for medicinal purposes. Many treatments and diagnostics would not be considered “healthy” but still make sense in the overall health picture. I would definitely do the Gatorade next time because the other option was absolutely nauseating and I have been dreading doing it again for the past 10 years. Seems like a no-brainer to me.

  9. 9
    Marcia Mullins on May 18, 2012

    Liquid Gatorade is water and high fructose corn syrup. HFCS is very unhealthy and is majorly responsible for the epidemic of obesity in this country.

    I would discourage anyone from using Liquid Gatorade at any time.

    I’m not sure if the powered Gatorade has HFCS or if it would be appropriate to mix with Miralax for this purpose, but one could ask one’s doctor about it.

    1. 10
      Kate Murphy on May 23, 2012

      I don’t think the issue is drinking Gatorade every day, but only in very rare instances before colonoscopy.

      Gatorade replaces electrolytes lost during the colonoscopy prep and fights possible dehydration which can lead to heart and kidney damage.

      For most people the prep would be done only once every ten years. If polyps were found, the prep might have to be repeated in 3 to 5 years.

      Given that colonoscopy saves lives, any possible risk from Gatorade is well-balanced against lives saved through colonoscopy screening.

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