Colonoscopy Bowel Prep Instructions
A complete guide to preparing for your colonoscopy, including diet changes, bowel prep solutions, and tips to make the process easier.
⚠️ Follow Your Doctor's Instructions
This is a general guide. Always follow the specific instructions provided by your gastroenterologist or endoscopy center. Different facilities may use different prep protocols. If your instructions differ from this guide, follow what your doctor gave you.
Why Prep Matters
Proper bowel preparation is crucial for a successful colonoscopy. Your colon must be completely clean for the doctor to see the entire lining clearly. Poor preparation can result in:
- Missed polyps or lesions — residual stool can hide abnormalities
- Incomplete exam — the doctor may not be able to see the entire colon
- Repeat procedure — you may need to come back and do it again
- Higher cancer risk — missed polyps can develop into cancer
Studies show that up to 25% of colonoscopies have inadequate prep. Following instructions carefully significantly improves your chances of a complete, successful exam.
Preparation Timeline
Contact your doctor about any medications you take, especially:
- Blood thinners (warfarin, Eliquis, Xarelto, Plavix) — may need to stop 3-7 days before
- Diabetes medications — may need dose adjustments
- Iron supplements — typically stop 5-7 days before (turns stool dark)
- NSAIDs (ibuprofen, aspirin) — may need to stop
Begin eating low-residue foods that are easy to digest. Avoid:
- Nuts, seeds, and popcorn
- Raw vegetables and whole grains
- High-fiber cereals and breads
- Dried fruits and berries
No solid food at all. Only clear liquids you can see through. Stay well hydrated.
Drink the first half of your bowel prep solution as directed. Stay near a bathroom — expect frequent bowel movements starting 1-3 hours after drinking.
Drink the second half of your prep. This "split-dose" approach is more effective than taking all the prep the night before. Finish all liquids 2-4 hours before your procedure time.
Clear Liquid Diet
The day before your colonoscopy, you can ONLY consume clear liquids. Here's what's allowed and what to avoid:
| ✅ Allowed | ❌ Not Allowed |
|---|---|
| Water (plain or flavored) | Milk or dairy products |
| Clear broth (chicken, beef, vegetable) | Orange juice or juice with pulp |
| Apple juice, white grape juice | Smoothies or protein shakes |
| Sports drinks (Gatorade, Pedialyte) | Any solid food |
| Clear sodas (ginger ale, Sprite) | Alcohol |
| Black coffee or tea (no cream) | Coffee or tea with cream/milk |
| Popsicles (no fruit chunks) | Red, purple, or blue colored drinks |
| Jell-O (no red/purple/blue) | Red, purple, or blue Jell-O |
| Hard candy (no red/purple/blue) | Anything you can't see through |
⚠️ Avoid Red, Purple, and Blue
Do not consume anything red, purple, or blue colored. These dyes can coat the colon lining and be mistaken for blood or inflammation during the procedure.
Bowel Prep Solutions
Your doctor will prescribe a specific bowel prep. Common options include:
| Prep Name | Volume | Key Features |
|---|---|---|
| GoLYTELY / NuLYTELY | 4 liters (1 gallon) | Most effective; large volume can be challenging |
| MiraLAX + Gatorade | ~2 liters | Lower volume; uses over-the-counter products |
| SUPREP | ~1 liter of solution + water | Low volume; tastes salty/bitter |
| Clenpiq | 2 small bottles + water | Lowest volume; berry flavor |
| SUTAB | 24 tablets + water | No liquid prep to drink; take tablets with water |
Tips to Make Prep Easier
Chill the Solution
Refrigerate your prep solution. Cold liquid is much easier to drink than room temperature.
Use a Straw
Drinking through a straw placed toward the back of your mouth reduces the taste contact.
Suck on Hard Candy
Lemon drops or ginger candy between sips can help clear the taste. Avoid red/purple colors.
Set a Timer
Drink one 8oz glass every 10-15 minutes. Steady pacing is easier than rushing.
Stay Near Bathroom
Bowel movements start 1-3 hours after drinking. Plan to stay home near a toilet.
Protect Your Skin
Use wet wipes instead of toilet paper. Apply petroleum jelly or diaper cream to prevent irritation.
💡 Pro Tip: Split-Dose Prep
Research shows that splitting your prep (half the evening before, half the morning of) results in better colon cleansing than drinking all of it the night before. Ask your doctor about split-dose instructions.
What to Expect During Prep
- Frequent bowel movements — you'll have many trips to the bathroom, usually 10-20+ times
- Watery stools — your stools will become liquid and eventually clear or light yellow
- Cramping — mild abdominal cramping is normal as the solution works
- Bloating and nausea — take breaks if needed; sip ginger ale to settle your stomach
- Chills — drinking cold liquid can make you feel cold; keep a blanket nearby
- Hunger — clear broth and popsicles can help; remember it's only one day
How to Know Your Prep is Complete
Your colon is clean when your bowel movements become clear or light yellow with no solid particles — like urine. If your output is still brown or has chunks, the prep may be inadequate.
Day of Procedure Checklist
- ☐ Finish second dose of prep (usually 4-6 hours before procedure)
- ☐ Stop all liquids 2-4 hours before procedure time (as instructed)
- ☐ Take any morning medications with small sip of water (if approved)
- ☐ Wear comfortable, loose clothing
- ☐ Leave jewelry and valuables at home
- ☐ Bring ID, insurance card, and list of medications
- ☐ Have someone with you to drive you home
- ☐ Plan to take the rest of the day off