Colonoscopy is one of the most effective tools available for preventing colon cancer. However, its efficacy depends heavily on how well you prepare. Proper preparation helps your doctor see clearly, keeps your procedure safe and avoids the need for a repeat exam.
If you're scheduled for a colonoscopy, this guide will walk you through every step of the preparation process. Specifically, the split-dose method using either MiraLax® or GoLYTELY® prep solution.
Important: Always follow the specific instructions provided by your healthcare provider, as some prep times and medications may be customized based on your health conditions and current medications.
7 days before your colonoscopy
Preparation begins one week before your procedure. At this stage, you'll need to make some important adjustments to your medications and diet.
Stop taking:
- Iron supplements
- Fiber supplements (such as Metamucil®)
- Anti-diarrheal medications (such as Imodium®)
Stop eating:
- Nuts
- Seeds
- Popcorn
- All raw fruits and vegetables
If you have a history of constipation, notify your provider or scheduling office before your procedure. You may need additional preparation instructions to ensure your prep is effective.
The day before your colonoscopy: Clear liquid diet
The day before your colonoscopy, you must follow a strict clear liquid diet. This means:
Allowed
- Water
- Broth
- Apple juice
- Tea
- Jello
- Sports drinks (like Gatorade)
Avoid
- Any red- or purple-colored liquids
- Solid foods of any kind
Colonoscopy prep schedule: Split-dose method
The day before — Afternoon prep
3 p.m. – Take 4 Dulcolax® tablets with 8 oz of clear liquid
5 p.m. – Take 2 Simethicone tablets (such as Gas-X® or a generic equivalent) to reduce gas bubbles and improve visibility
5 p.m. – Begin mixing and drinking the first half of your prep solution
Mixing your prep solution
If using MiraLax: Mix the entire 238-gram bottle of MiraLax with 64 ounces of Gatorade in a large container.
If using GoLYTELY: Fill your container with water as directed in your specific instructions. You will also need to drink additional water after the prep solution.
How to drink your prep solution
- Drink 8 ounces every 15 to 30 minutes.
- If you feel nauseous, take short breaks, then continue.
- Complete the first half of the solution during the evening.
The morning of your procedure (Second half of prep)
On the morning of your colonoscopy, at your instructed time, drink the second half of your prep solution:
- Drink 4 additional 8-ounce glasses of prep solution
- Begin drinking 6 hours before your scheduled arrival time
- Make sure all prep is finished at least 4 hours before your arrival time
Nothing past your lips after this point — not even water!
How do you know your prep is working?
By the end of your preparation, your stool should appear as a clear or light-yellow liquid, similar in color to urine.
Even if your stool looks clear after the first half, you must complete the entire prep. Skipping the second half can result in an incomplete exam, meaning your procedure may need to be rescheduled.
Important reminders before your procedure
- Arrange a ride home – You must have a responsible adult available to drive you home after your colonoscopy. You will be sedated during the procedure and will not be able to drive yourself.
- Medications – You may be able to use generic drug names for your prep medications. Always check with your pharmacist or provider if you are unsure about substitutions
- Follow your personalized instructions – Some prep times and instructions are customized based on your medications and health conditions. Always refer to the specific instructions given to you by your care team.
Colonoscopy prep checklist
Use this quick checklist to make sure you're on track:
- Stopped iron supplements, fiber supplements and anti-diarrheal 7 days before.
- Stopped eating nuts, seeds, popcorn and raw fruits and vegetables 7 days before.
- Notified provider of any constipation history.
- Followed clear liquid diet the day before.
- Took 4 Dulcolax tablets at 3 p.m.
- Took 2 Simethicone tablets at 5 p.m.
- Mixed and began drinking first half of prep solution.
- Completed second half of prep 6 hours before arrival.
- Finished all prep at least 4 hours before arrival time.
- Confirmed a responsible adult is available to drive you home.
- Stool is clear or light yellow before leaving for your appointment.
Final thoughts: You've got this
Colonoscopy prep isn't the most comfortable experience, but it is incredibly important. When you follow these instructions carefully, you're helping your medical team do their job effectively and ensuring the best possible outcome for your health.
If you're unsure about any part of the process, do not hesitate to call your healthcare provider. Your care team is there to support you every step of the way.
Thank you for taking this important step for your wellbeing. Good luck. You've got this!
