Types of Colonoscopy Prep Kits

Colorectal cancer is the third-leading cause of cancer deaths in the U.S.. To rule out this cancer, experts recommend colorectal cancer screening — such as a colonoscopy. But, as of 2020, approximately 20% of people between 50 to 75 years old had never been screened for colorectal cancer.

Many people feel that preparing for a colonoscopy is more difficult than the colonoscopy itself. Fortunately, more prep kit options are now available to make preparing for the procedure a little more pleasant.

Here, we’ll discuss how to prepare for a colonoscopy and the different bowel prep kit options.

Colonoscopy prep instructions

It’s important to follow preparation instructions to help your doctor get high-quality images of your colon during the colonoscopy. Poor preparation could lead to lower-quality images. 

If your gastroenterologist doesn’t have clear photos from the procedure, they’re more likely to miss seeing something that could be concerning, like a polyp. A polyp is an extra growth in your colon. And though most are not dangerous, some may turn cancerous. If images show a polyp, it's removed and tested. But, if the colon images are of low quality, you may have to repeat your colonoscopy so your doctor can be sure no polyps were missed. 

Colonoscopy prep diet

In the past, you could only drink clear liquids at least 1 day before your colonoscopy. A clear liquid diet includes the following:

• Clear broth

• Coffee or tea (without milk)

• Gelatin desserts (without red or purple coloring)

• Ginger ale

• Ices

• Sherbert

• Water 

You could also drink clear (see-through) fruit juices including apple juice and lemonade.

Now, experts state that a low-residue diet is a potential option. A low-residue diet is a low-fiber diet. So, avoid high-fiber foods — like fruits, vegetables, and whole grains. If the doctor cannot get high-quality images of your colon, your doctor might switch you back to a clear liquid diet for future colonoscopies.

In addition to diet changes, if you take blood-thinning or diabetes medications, your doctor may recommend some adjustments to these medications for the colonoscopy procedure.

Types of colonoscopy prep kits

With so many colonoscopy prep kits available, which one is best for you? The “best” colonoscopy prep kit will vary by person, depending on your medical conditions, age, preferences, and costs. 

Before your colonoscopy procedure, have a discussion with your doctor to help you choose the best prep kit for you.

GoLYTELY

GoLYTELY is a 4L-polyethylene-glycol (PEG) solution. It comes as a powder that you mix with water. Usually, it’s mixed with 240 mL (about 8 oz) of water, which is a large quantity that many find difficult to ingest. 

Your healthcare provider may have specific instructions for how to take GoLYTELY, so make sure you read the medication label carefully. GoLYTLEY contains sulfate, which many people find gives it a bad taste.  

NuLYTELY

Like GoLYTELY, NuLYTELY is also a 4L PEG solution — but without sulfate. Also like GoLYTELY, it’s usually diluted with 240 mL of water. Compared to GoLYTELY, many find NuLYTELY tastes better. 

Moviprep

Moviprep is a low-volume PEG solution with ascorbic acid. Although this colonoscopy kit is available in a smaller volume of 2L, it’s not for everybody. If you have glucose-6-phosphate dehydrogenase (G6PD) deficiency, avoid this prep kit. 

People with G6PD deficiency have low amounts of G6PD, which is a type of protein that influences how red blood cells (RBCs) work. Certain medications and foods in people with G6PD deficiency might lead to an abnormal breakdown of RBCs. 

Plenvu

Plenvu is another low-volume PEG solution with ascorbic acid that should also be avoided in people with a G6PD deficiency, but Plenvu requires less volume than Moviprep.

For every colonoscopy prep kit, however, keep in mind that drinking plenty of fluids — in addition to using the prep kit — is important for a successful procedure.

OsmoPrep

OsmoPrep is a sodium phosphate-based colonoscopy prep kit. It’s available as tablets for you to take with water. 

The tablets have also been associated with kidney problems (acute phosphate toxicity), so they carry a black-box warning. Additionally, OsmoPrep can lead to abnormal amounts of salt and water in the body. 

Suprep or Sutab

Both Suprep and Sutab are sodium sulfate-based colonoscopy prep kits, which aren’t any less effective than PEG solutions. Compared to NuLYTELY, sodium sulfate-based prep kits might cause fewer bloating side effects. Also, unlike sodium phosphate-based prep kits like OsmoPrep, Suprep and Sutab have no link to abnormal salt and water amounts in the body.

Suprep is available as a solution that requires mixing with water. Sutab, on the other hand, is available as tablets for you to take with water.

Clenpiq

Clenpiq is a combination sodium picosulfate-based colonoscopy prep kit. When compared to a low-volume 2L PEG solution with bisacodyl 10 mg, the combination prep kit isn’t any less effective.

However, the combination product should be avoided in people with severe kidney impairment. Additionally, although rare, this product is linked to abnormal salt amounts in the body.

Other medications used to help prepare for colonoscopy

Instead of the above prescription colonoscopy prep kits, healthcare providers can also recommend the following over-the-counter (OTC) options.

Bisacodyl

Bisacodyl is an OTC medication that treats constipation. While it isn’t FDA-approved for bowel prep, healthcare providers may recommend bisacodyl 5 mg or 10 mg in combination with Miralax before a colonoscopy procedure. 

More on Miralax and its use with bisacodyl next.  

Miralax 

Miralax is available as an OTC product to relieve constipation. Although not FDA-approved as a colonoscopy prep kit, healthcare providers often recommend Miralax as an alternative low-volume PEG solution. Miralax will require mixing with 64 ounces (2L) of a sports drink, like Gatorade. If your healthcare provider recommends Miralax for bowel prep, they might recommend you take bisacodyl, too.

When comparing this Miralax and bisacodyl combination against the standard colonoscopy prep, like GoLYTELY, study results have been mixed. Safety data is also limited, but there are rare reports of abnormal salt amounts in the body.

Magnesium citrate

Magnesium citrate is also available as an OTC product to relieve constipation. Like Miralax, it’s also not FDA-approved as a colonoscopy prep kit. 

In fact, there is little effectiveness and safety data for using magnesium citrate for colonoscopy preparation. Due to the potential for serious side effects, however, experts don’t usually recommend magnesium citrate — especially in older adults or people with a kidney condition.

Frequently asked questions about colonoscopy prep

Preparing for your colonoscopy can understandably be inconvenient and unpleasant. Below, we’ll discuss a few common questions people have about preparing for a colonoscopy. These questions and answers will help you know what to expect and how to limit side effects.

How long does colonoscopy prep take?

For most people, the doctor will recommend changing to a clear liquid or low-residue diet 1 day before the procedure. In some people, however, the doctor may recommend the change in diet 2 days before the colonoscopy appointment.

As for using the colonoscopy prep kit, it is usually completed in two separate doses. Most people will take part of the prep kit the night before the procedure and finish the kit on the day of the procedure for morning colonoscopy appointments. People with afternoon appointments, on the other hand, will take all of the colonoscopy prep kit in the morning of the procedure day.

Will I be up all night with colonoscopy prep?

People with morning colonoscopy appointments will usually wake up around 2AM to 3AM in the morning to take their second dose of the prep kit.

If you prefer to not wake up so early in the morning, talk with your doctor about having an afternoon appointment for your colonoscopy. However, you will need to take all of your prep kit in the morning before your afternoon colonoscopy.

How can I drink colonoscopy prep without throwing up?

Taking the colonoscopy prep kit can feel difficult to many people. Consider the following tips that may help improve the taste of prep kits.

• Chill the prep kit solution in the refrigerator. Taking the solution chilled might help with taste.

• Ask for flavoring packs. Ask your doctor to give you a prescription for a prep kit with flavoring packs, which might hide some of the unpleasant taste.

• Discuss with your doctor about NuLYTELY. NuLYTELY is a sulfate-free version of GoLYTELY. Without the sulfate, NuLYTELY might taste better than GoLYTELY.

• Take the prep kit as two separate doses. Ask your doctor to schedule your colonoscopy procedure in the morning to take your prep kit in two doses. You may have to wake up at 2AM or 3AM for your second dose. With two separate doses of the prep kit, however, you may experience fewer side effects — like bloating, nausea, and vomiting.

• Discuss with your doctor about OsmoPrep or Sutab. If you prefer to take a lot of tablets over drinking large amounts of a prep solution, then OsmoPrep or Sutab are potential options. Since these tablets are not for everyone, however, talking with your doctor will help you decide whether a tablet prep kit is the best option for you. 

What is the easiest colonoscopy prep to tolerate?

The easiest colonoscopy prep kit to tolerate will vary by person — based on your preferences, age, and medical conditions. 

To help find the best prep kit for you, have a discussion with your doctor.

Why trust our experts?

Written by:

Ross Phan, PharmD, BCACP, BCGP, BCPS

Ross Phan is a board-certified clinical pharmacist. She has roughly two decades of healthcare experience — with most of her experience being pharmacy related.

Reviewed by:

Amy B. Gragnolati, PharmD, BCPS

Amy Gragnolati, PharmD, BCPS, is a pharmacy editor for GoodRx. Amy currently holds her pharmacist license in Georgia and California.

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