Colonoscopy prep pills are a type of laxative medication used to clean out your bowels before a colonoscopy. Some people find the pills easier to take than the laxative liquid solutions that are often prescribed for this purpose.

During a colonoscopy, a doctor inserts a long, thin, flexible tube fitted with a video camera into your rectum. This allows your doctor to check for signs of cancer and other conditions inside your colon.

Emptying stool from your bowels ahead of a colonoscopy helps your doctor have a clear view of the inside of your large intestine.

Keep reading to learn more about colonoscopy prep pills as well as liquid solutions for colonoscopy prep, how they work, their effectiveness, and how to take them.

Colonoscopy prep pills are laxatives. They work by stimulating the muscles in the walls of the intestines to move stool through the bowels.

Most colonoscopy preparations are liquid solutions that you drink. But a few colonoscopy preparation medications are available in tablet form.

Oral sodium phosphate medications include the brand name OsmoPrep. This medication was once available over the counter in the United States. But due to safety concerns associated with dosing, it’s now only available with a prescription from a doctor.

In 2020, the Food and Drug Administration (FDA) approved another colonoscopy prep pill sold under the brand name Sutab. Sutab contains a combination of the following active ingredients:

  • sodium sulfate
  • magnesium sulfate
  • potassium chloride

It is only available with a doctor’s prescription.

If you’re scheduled for a colonoscopy, your doctor can offer detailed instructions about which medication to take before your procedure. If you’d prefer to take oral tablets instead of a liquid solution for your colonoscopy prep, ask your doctor whether oral tablets are a suitable option for you.

Clinical data suggests that colonoscopy prep tablets are generally as effective as liquid solutions. Sutab is likely more effective than OsmoPrep. They also differ in terms of safety.

One of the biggest issues with liquid prep solutions is they require drinking a large volume of fluids. One of the advantages of liquid prep solutions, though, is that they typically result in a minimal loss of electrolytes. Miralax-based preps tend to be the safest. But these generally involve drinking more fluid than other types of bowel preps.

Keep in mind that not all health insurance companies will cover the cost of newer brand-name preps, such as Sutab. If you have insurance, always check with your insurance provider. They can let you know what types of preps will be covered and which may require out-of-pocket expenses.

Effectiveness of Sutab

A few recent clinical trials compared the safety and effectiveness of sodium sulfate (Sutab) with other FDA-approved colonoscopy preparations.

In particular, a 2021 study looked at 515 adult participants undergoing colonoscopies. The authors reported that Sutab was likely to provide successful bowel cleansing in 92 percent of participants. Other bowel prep solutions provided successful bowel cleansing in 89 percent of participants.

A 2021 letter published in the Journal of the American Medical Association reported that Sutab is as effective as MoviPrep and Clenpiq, which are both liquid prep solutions. But Sutab may cause additional gastrointestinal side effects.

Also, more research is needed to evaluate the safety of Sutab among people who have heart failure, kidney problems, or electrolyte imbalances.

Effectiveness of OsmoPrep

A 2019 prospective clinical trial of 4,339 colonoscopies compared the effectiveness of 7 bowel prep prescriptions, including OsmoPrep but not Sutab.

The authors reported that all seven types were effective, but OsmoPrep scored lower than other preparations. For comparison:

  • OsmoPrep provided adequate bowel cleansing in 81.7 percent of individuals.
  • MoviPrep provided adequate bowel cleansing in 91.1 percent of individuals.
  • Miralax with Gatorade provided adequate bowel cleansing in 92.5 percent of individuals.

The study did not address concerns regarding the safety of OsmoPrep. OsmoPrep has been linked to a kidney complication called acute phosphate nephropathy.

According to the FDA label, OsmoPrep may not be safe for people who:

  • are older
  • have heart failure
  • have kidney problems
  • have end stage liver disease
  • have electrolyte imbalances
  • take certain medications

Both Sutab and OsmoPrep are split-prep medications. That means you’ll have to take one dose in the evening before your colonoscopy and another dose the next morning, several hours before your procedure.

Dosing information for Sutab

  • First dose. Take 12 tablets with 48 ounces of water the evening before your colonoscopy.
  • Second dose. Take 12 tablets with 48 ounces of water 5 to 8 hours before your colonoscopy.
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Dosing information for OsmoPrep

  • First dose. Take 20 tablets with 40 ounces of clear liquid the evening before your colonoscopy.
  • Second dose. Take 12 tablets with 24 ounces of clear liquid 3 to 5 hours before your colonoscopy.
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It’s important to read your doctor’s instructions very carefully, as the evening and morning doses might not be the same.

Your physician will provide you with detailed instructions on how to prepare for your colonoscopy. It’s extremely important to follow these instructions and ask for clarification when necessary.

Here’s how to prepare your bowels before a colonoscopy:

  • Limit your fiber intake. Your doctor will probably ask you to follow a low residue diet in the days leading up to your colonoscopy to limit the amount of fiber in your bowels.
  • Follow a clear liquid diet. On the day before the procedure, you’ll typically need to consume only transparent liquids, such as water, fat-free broth, sports drinks, and pulpless fruit juice.
  • Take your colonoscopy prep pills exactly as prescribed. You’ll need to take your prep pills in one dose the night before your procedure and again the following morning. These two doses may be slightly different. Make sure you follow your doctor’s instructions carefully.
  • Drink water. Your prescription will include instructions on how much water to drink with your prep pills.
  • Stay close to the bathroom. The prep pills will cause diarrhea, so it’s best to stay close to the bathroom after taking them. In addition, you might experience other gastrointestinal symptoms such as bloating and abdominal cramps.
  • Avoid eating before your colonoscopy. Although you’ll likely be hungry, it’s important to avoid all food and drink in the hours leading up to your procedure.
  • Ask your doctor about prescription medication. If you need to take prescription medication, ask your doctor when you should do so before your colonoscopy.

If your bowel isn’t cleaned out enough, your physician may have to reschedule your procedure.

Prep pills are laxatives used to empty and clean the bowels before a colonoscopy. They are available with a prescription from your doctor.

Prep pills are easier to take than some liquid solutions and, in most cases, just as effective. However, there are some safety concerns, particularly with OsmoPrep.

Your doctor will evaluate which bowel prep is best for you according to your age, health, and any medications you take. It’s very important to follow your doctor’s instructions carefully when doing a colonoscopy prep. If a prep isn’t done correctly, it can compromise the effectiveness of the procedure.