Have They Found a Better Colonoscopy Prep?

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.


  1. Marcia Mullins says

    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.

    • Kate Murphy says

      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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