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What is the best cleanse for a colonoscopy?


A colonoscopy is a common medical procedure used to examine the interior of the large intestine (colon and rectum) for abnormalities or disease. In preparation for a colonoscopy, the colon must be thoroughly cleansed and emptied of all stool. This is done through following a strict liquid diet and using strong laxatives or “colon prep solutions” for 1-2 days before the procedure. Having a properly cleansed colon is critical for your doctor to be able to visualize the entire lining of the colon and rectum during the colonoscopy. An inadequate bowel prep can result in a failed procedure and the need to reschedule and repeat the uncomfortable preparation. So choosing the right type of colonoscopy prep is important. Here we will discuss the different prep options available and provide guidance on which is considered the best cleanse for a successful colonoscopy experience.

Types of Colonoscopy Preps

There are a few different types of colonoscopy preps your doctor may recommend:

Polyethylene Glycol (PEG)

PEG solutions work by drawing water into the colon to induce diarrhea and clear out stool. Some examples of PEG preps include:

  • Golytely
  • Colyte
  • Miralax and Gatorade
  • Dulcolax and Miralax

PEG solutions are among the most commonly prescribed because they are safe, effective, and require drinking a lower volume of liquid than some alternatives. However, some people find the taste unpleasant.

Sodium Phosphate (NaP)

NaP solutions pull water into the colon via osmosis to stimulate evacuation of stool. Some examples include:

  • Fleet Phospho-soda
  • OsmoPrep

These preps involve drinking a relatively small amount of liquid, but are no longer preferred due to the risk of electrolyte imbalances.

Magnesium Citrate

Magnesium citrate works as a saline laxative, drawing water into the colon through osmosis. Patients drink a bottle of magnesium citrate liquid.

Magnesium citrate is convenient as it does not require mixing solutions or drinking high volumes of liquid. However, some patients may find the taste unappealing.

Sodium Picosulfate

Sodium picosulfate stimulates the colon to contract and expel stool. Examples include:

  • Prepopik
  • Clenpiq

These newer options involve drinking lower volumes of prep solution. However, some patients report side effects like headache or nausea.

Evaluating the Best Colonoscopy Prep

When evaluating which is the best colonoscopy prep, the following factors should be considered:


The most important quality of a colonoscopy prep is how thoroughly and effectively it cleanses the colon. If stool is left behind, it can obscure visualization of the colon lining.

Studies have found the following preps to be highly effective at colon cleansing:

  • PEG solutions (Colyte, Golytely)
  • Sodium picosulfate (Prepopik, Clenpiq)

Magnesium citrate and oral NaP solutions tend to be less effective than the PEG and sodium picosulfate options.


Drinking large volumes of unpleasant tasting liquids and enduring diarrhea can make prep unpleasant. Tolerability considers how easy the prep is to complete based on taste, volume, and side effects.

PEG solutions often receive poor marks for tolerability due to their salty taste and large fluid volume required.

Picosulfate solutions like Clenpiq and Prepopik involve drinking less liquid so are often better tolerated.


Some preps carry risks of fluid and electrolyte imbalances, so should be used cautiously in people with kidney disease or congestive heart failure.

Oral sodium phosphate preps are no longer preferred because of risks of electrolyte disturbances.

PEG and Picosulfate preps are considered very safe with minimal risks.


The simpler a prep is to prepare and complete, the more convenient it is. Preps requiring mixing multiple bottles of solutions or repetitive steps can be inconvenient.

Magnesium Citrate is very convenient as it only requires drinking one pre-mixed bottle.

Picosulfate preps like Prepopik and Clenpiq are also convenient as they involve drinking two pre-mixed, lower volume doses.


Out of pocket costs for different preps vary based on insurance coverage. Generic PEG solutions tend to be more affordable while branded preparations may be pricier.

Here is a table comparing key features of common colonoscopy preps:

Prep Type Effectiveness Tolerability Safety Convenience Cost
PEG (Colyte, Golytely) Very effective Poor Very safe Moderate Low
Picosulfate (Prepopik, Clenpiq) Very effective Good Very safe High Moderate
Magnesium Citrate Moderately effective Good Safe Very high Low
NaP (OsmoPrep, Fleet) Moderately effective Moderate Moderate safety High Moderate

Best Colonoscopy Prep Overall

Considering the important factors of efficacy, safety, tolerability, and convenience, the sodium picosulfate preparations Clenpiq and Prepopik rise to the top as the best colonoscopy preps overall.

Studies have shown these new-generation preparations provide colon cleansing on par with the highly effective PEG solutions. The major advantages of the picosulfate preps are improved taste and requiring drinking less fluid volume. This leads to better tolerability and patient compliance with completing the preparation. These preparations are extremely safe with minimal fluid shifts or electrolyte disturbances. And the prep schedule is simple and convenient, usually requiring ingesting 2 pre-mixed bottles about 12 hours apart the day before the procedure.

For these reasons, most gastroenterologists now consider sodium picosulfate preps like Clenpiq and Prepopik to be the preferred and best colonoscopy preparation. The American Gastroenterological Association recommends these newer low-volume preparations as first-line agents for colon cleansing before colonoscopy.

Some downsides are that these preparations are more expensive than older options like PEG solutions or magnesium citrate. Some insurance plans may not cover them. Additionally, though rare, some patients report headache or nausea side effects.

Overall, the high efficacy, safety, tolerability, and convenience profile make the sodium picosulfate preparations the best choice for colonoscopy prep for most patients. Just be sure to follow your physician’s specific instructions to properly complete the preparation for a successful colonoscopy.

Tips for Improving Tolerance of Colonoscopy Prep

While some preps are better tolerated than others, drinking large amounts of laxative solution is never pleasant. Here are some tips to help make completing the prep more tolerable:

  • Stay near a toilet once you start drinking the prep solution
  • Add lemon juice to improve salty tastes of some preps
  • Drink with a straw placed far back on your tongue to avoid more taste receptors
  • Rinse mouth with water, clear soda, or mouthwash after finishing each dose
  • Suck on hard candies between doses to mask unpleasant tastes
  • Chill prep solution for at least 2-3 hours before drinking to improve palatability
  • Consume all required prep doses even if you think stool has cleared – inadequate prep can ruin the colonoscopy

The colonoscopy prep will require staying near a bathroom for frequent bowel movements. Be sure to stay well hydrated by drinking clear liquids. Electrolyte drinks like Gatorade can help prevent fluid imbalances caused by diarrhea.

A successful colonoscopy starts with selecting an effective colon cleanse prep and being diligent in properly completing the preparation. Discuss the best options with your doctor and follow all prep instructions carefully. This will help ensure your colon is well cleansed, allowing your doctor to thoroughly inspect your colon and rectum while keeping your procedure easy and painless.


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Saltzman, JR. Picking the Best Bowel Prep for Colonoscopy. Medscape Gastroenterology. Oct 26, 2018.

Matro R, Shnitser A, Spodik M, Daskalakis C, Katz L, Murtha A, Kastenberg D. Efficacy and safety of low-volume PEG solutions for colon cleansing before colonoscopy: a meta-analysis. Gastrointest Endosc. 2016 Feb;83(2):324-331.e1. doi: 10.1016/j.gie.2015.08.041. Epub 2015 Oct 16. PMID: 26474840.