What Medications Can I Take Before My Colonoscopy?

A woman takes prescribed medication for bowel preparation holding a glass of water and medicine

What Medications Can I Take Before My Colonoscopy?

A healthy digestive system is crucial for our overall well-being, as many people experience gastrointestinal issues. In the U.S. alone, over 70 million people suffer from digestive disorders. A colonoscopy is essential to detecting and preventing these problems.

However, the success of a colonoscopy largely depends on how well you prepare your bowel. Ensuring your bowel is thoroughly cleansed before the procedure is crucial for accurate results you can rely on. Thankfully, there are medications to help you achieve proper bowel cleansing, making the whole process smoother and more effective.

The Importance of Bowel Preparation

Bowel preparation is a critical step in ensuring the success and accuracy of a colonoscopy. Following your healthcare provider’s bowel preparation instructions ensures that your colon is adequately emptied of stool and debris. This, in turn, allows for a smooth and safe insertion of the colonoscope during the procedure, reducing discomfort and minimizing the risk of complications.

A clear view of the colon’s inner lining also enables the physician to identify potential health issues early, such as polyps or tumors, improving the chances of timely intervention and treatment.

Prescription Medications

Your doctor may prescribe specific medications to thoroughly clean your bowels before your colonoscopy. Here are the prescription medications commonly used for bowel preparation:

Polyethylene Glycol (PEG)

Polyethylene Glycol is one of the most commonly prescribed medications for bowel preparation. It comes in various formulations and is typically mixed with water or a clear liquid. As a large-volume laxative, PEG draws water into the colon, promotes bowel movements, and clears stool. One should take PEG one to two days before the colonoscopy. You may need to take it in divided doses or as a single large dose, followed by plenty of clear liquids.

Sodium Phosphate

Developers created sodium phosphate (NaP) agents to offer patients a milder option compared to polyethylene glycol (PEG) bowel preparations, which require them to consume up to 4 liters of liquid over a few hours. NaP agents are available as oral solutions, tablets, or enemas.

Sodium phosphate acts as an osmotic laxative, drawing water into the colon to soften and eliminate stool. It’s usually taken the evening before your colonoscopy. Make sure to follow the recommended dosage and consume lots of clear liquids.


Doctors may prescribe Lubiprostone for patients with chronic constipation or irritable bowel syndrome with constipation (IBS-C). This medication helps increase fluid secretion in the intestines, facilitating bowel movements. Start taking lubiprostone a few days before the colonoscopy, as instructed by your healthcare provider.

Laxative Suppositories or Enemas

Sometimes, your doctor may recommend using laxative suppositories or enemas to provide targeted relief and ensure complete bowel evacuation. Use laxative suppositories or enemas on the colonoscopy day or as the preparation plan advises.

Over-The-Counter Medications

If you prefer over-the-counter options for your colonoscopy bowel preparation, several readily available medications can aid in clearing your bowels effectively. These non-prescription choices are accessible and can be as effective when used correctly. Here are the over-the-counter medications commonly used for bowel preparation:

Magnesium Citrate

Magnesium citrate is an osmotic laxative that can be an effective choice for bowel preparation. It’s usually taken in liquid form and helps clear the colon by inducing bowel movements. Take magnesium citrate the evening before the colonoscopy, as directed. Ensure to follow the recommended dosage and consume enough clear liquids.

Bisacodyl Tablets

Bisacodyl is an over-the-counter stimulant laxative, often sold in tablet form. It works by directly stimulating the intestines, promoting bowel movements. Some doctors may recommend using bisacodyl alongside other bowel preparation methods for more thorough cleansing. Take bisacodyl tablets the day before the colonoscopy or as part of the preparation plan.


Senna is a natural laxative derived from the Senna alexandrina plant. It’s available in various forms, such as tablets or herbal teas, and works by stimulating the muscles in the intestines to move stool along. Start taking Senna a day or two before the colonoscopy. Follow the recommended dosage and schedule.

Allergy or Sensitivity to Medications

If you have a history of allergies or sensitivities to medications, inform your healthcare provider before starting bowel preparation for your colonoscopy. Some laxatives used in the preparation process may contain ingredients that could trigger adverse reactions in susceptible individuals.

By sharing your medical history and medication allergies with your doctor, they can tailor a bowel preparation plan that avoids problematic substances while ensuring effective bowel cleansing.

Follow Your Doctor’s Instructions

Your healthcare provider will provide personalized guidelines, including which medications to take, their dosages, and when to start your bowel preparation. Following these instructions ensures effective bowel preparation and a successful colonoscopy. Here are some guidelines to remember.

Medications: Take the prescribed bowel preparation medications as instructed by your doctor. Follow the recommended dosages and timings for each medication to achieve optimal results.

Clear Liquid Diet: Your doctor may advise you to follow a clear liquid diet the day before the colonoscopy. This diet typically includes water, clear juices, broth, and herbal tea.

Fasting Instructions:  On the day of the colonoscopy, follow any fasting guidelines provided by your doctor. Abstain from eating or drinking anything, including water, during the specified fasting period.

Stay Hydrated: Throughout the bowel preparation period, drink plenty of clear liquids. Staying well-hydrated prevents dehydration and supports the effectiveness of the medications. Consume enough water, clear juices, and other allowed beverages as directed by your doctor.

Accessibility to Restrooms: During the preparation process, expect frequent and urgent bowel movements. Ensure you have easy access to restroom facilities for a more comfortable experience.

Always consult your doctor for personalized instructions and to address any specific concerns you may have before the procedure.

Get Help for Your Stomach and Colon Problems, Including Information on What Medications I Can Take Before My Colonoscopy, through Allied Digestive Health

A well-prepared bowel will make your colonoscopy procedure more comfortable and increase the chances of detecting potential health issues early on. Understanding the various medications available for bowel preparation allows you to make informed decisions in collaboration with your healthcare provider.

At Allied Digestive Health, we prioritize your digestive well-being. Our team of dedicated gastroenterologists is ready to guide you through effective bowel preparation, offering personalized medication recommendations and expert care. Contact our Care Centers today to schedule your colonoscopy and stay proactive in maintaining your overall well-being.

Gyan Gastroenterology (Sudha Nahar, MD)
(732) 873-1600
Associated Gastroenterology of Central New Jersey (Lawrence Pickover, MD)
(732) 846-2777
Steven H. Krawet, MD
(732) 390-5534
Nashed Botros, MD
(732) 967- 9595
Satya Kastuar, MD
(732) 821-0011
Yuri Volk, MD
(732) 677-2200
Cape Atlantic Gastroenterology Associates (Richard Troum, DO, FACG)