Colonoscopy preparation kits consist of laxatives and electrolytes in tablet or liquid form. There are different types of kits — some are prescription, while others available are over the counter.

Colonoscopy preparation is important to ensure an effective colonoscopy. It clears the bowels to allow a doctor to examine the colon properly.

This article looks at the different types of colonoscopy preparation kits, what each consists of, and how to take them.

A chemist packaging up a colononoscopy preparation kit -2.Share on Pinterest
Tom Werner/Getty Images

Colonoscopy preparation kits will consist of multiple tablets, which people take with plenty of water, or a powder that individuals mix with water to take over several hours.

Colonoscopy preparations contain an osmotic laxative, which pulls water into the stool to create softer, more frequent bowel movements.

Colonoscopy preparations also contain electrolytes to help prevent abnormalities in electrolyte levels.

PEG preparations are liquid formulas containing the laxative polyethylene glycol and an electrolyte solution to help prevent electrolyte changes.

People taking a PEG preparation usually consume 4 liters of fluid over several hours, either as a single or split dose.

PEG preparations are suitable for those with irritable bowel disease, as they will not irritate soft tissues inside the body.

PEG formulas may also be suitable for people with existing electrolyte imbalances or those who cannot have high sodium levels, such as individuals with heart or kidney failure.

PEG preparations are available in low or high volume doses, depending on how well people tolerate the prep. There are also sulfate-free options, which are less salty and may be easier for someone to tolerate.

Examples of PEG formulas include:

  • Moviprep

Saline-based formulas come in tablet form or a solution people mix with water. They contain hyperosmotic laxatives, such as sodium phosphate, magnesium citrate, or sodium sulfate. Examples of saline-based formulas include OsmoPrep and Suprep.

People may find tablets easier to take than liquid preparations. Still, these formulas may not be suitable for everyone, as there is a risk of side effects such as electrolyte imbalances.

Additionally, sodium phosphate is unsuitable for those with health conditions such as heart or kidney disease, as it can cause severe side effects.

There are also combination colonoscopy preparations, which include polyethylene glycol and magnesium citrate or sodium picosulfate.

Side effects of these preparations may include abdominal discomfort, nausea, or vomiting.

The following are common questions about colonoscopy preparation kits.

What is the easiest colonoscopy prep to tolerate?

Preparation tolerance can vary between people and may come down to personal preference and any health conditions that may affect which types are suitable.

The Colorectal Cancer Alliance published a survey from its online community on which colonoscopy preparations people preferred. The top results were as follows:

  • MiraLAX: 41%
  • DULCOLAX: 17%
  • Suprep: 13%
  • SUTAB: 10%
  • GoLYTELY: 8%
  • Moviprep: 4%

MiraLAX is a solution-based preparation, while DULCOLAX is a course of tablets people take the evening before a colonoscopy.

For PEG solutions, people may find taking a reduced salt, flavored preparation easier to tolerate. Sulfate-free PEG formulas may have an improved taste and smell, with less salt, which individuals may find easier to take.

What is the easiest colonoscopy prep to take?

Some people may find tablets easier to take, but this may vary for each individual.

People taking tablets will still have to drink plenty of fluids to prevent dehydration, and this type may not be suitable for those with certain health conditions.

A split-dose regimen, such as taking half the preparation the night before and the rest the morning of the procedure, may be easier for some individuals. Evidence suggests that split-dose preparations may be the best option.

What is the newest prep for colonoscopy?

Suflave is the newest type of colonoscopy preparation, which the Food and Drug Administration (FDA) approved in 2023.

People take Suflave as a liquid solution in two doses, with an extra 16 ounces of water after each dose.

Are there alternatives to a colonoscopy prep?

Colonoscopy preparation is an essential part of colorectal screening, so there is no other option. For a colonoscopy to be effective, the bowels must be clear for a doctor to examine the colon.

Pills or liquid: which is best?

A 2021 article suggests pill and liquid forms of colonoscopy preparations have the same effectiveness for clearing the bowels.

Each formula may have different side effects, and some types may be unsuitable for people with certain medical conditions, such as those with heart or kidney conditions.

It also depends on personal preference and which type individuals feel they can tolerate better.

Potential risks of complications with colonoscopy preparation can vary depending on the type of preparation but may include:

  • dehydration, if people do not drink enough fluids
  • magnesium toxicity with preparations containing magnesium
  • acute kidney injury with a high intake of sodium phosphate

A high intake of sodium phosphate may also have a risk of atypically high phosphate levels, low calcium or sodium levels, and seizures.

People will need to contact a doctor if they have any severe side effects while taking colonoscopy preparation, such as:

  • severe vomiting
  • blood in stools or vomit
  • change in heart rhythm
  • severe abdominal pain
  • dizziness
  • loss of balance
  • muscle weakness

People will also need to let a doctor know if they cannot complete their bowel prep or if it is not working, as they may need to reschedule their colonoscopy.

Colonoscopy preparation is an essential part of getting a colonoscopy, as it clears the bowel for effective examination.

Depending on personal preference and suitability, people may take colonoscopy preparation in tablet or liquid form.