A colonoscopy is a procedure in which a doctor uses a colonoscope (a long, flexible tube with a camera) to check for abnormalities in your large intestine (colon) and rectum. Your doctor will recommend a colonoscopy if you have gastrointestinal symptoms, a family history of colon cancer, or to screen for colon cancer, especially after age 50.
Before a colonoscopy, you will need to follow a clear liquid diet for 1-3 days and use a bowel prep solution to thoroughly cleanse your colon. Knowing what you can and cannot eat and drink before a colonoscopy is crucial for the exam’s success. Following the recommended diet ensures your doctor can clearly view your colon lining for polyps, inflammation, ulcers, and early signs of cancer.
What is a clear liquid diet before colonoscopy?
A clear liquid diet means you can only consume liquids that are see-through and easy to digest leading up to your colonoscopy appointment. Liquids and foods included on a clear liquid diet are:
- Water
- Fruit juices without pulp such as apple, white grape, strained lemonade
- Clear broth including chicken, beef or vegetable broth
- Plain gelatin
- Popsicles
- Tea or coffee without milk or cream
- Clear, carbonated beverages such as ginger ale, lemon-lime soda
- Hard candy
- Honey
- Sugar
- Clear nutritional supplements
The clear liquid diet strictly prohibits:
- Solid foods
- Milk or dairy products
- Juices with pulp
- Alcohol
- Red or purple liquids
Sticking to colorless fluids prevents any pigment from coloring the colon lining. Your doctor needs a clear view of the colon walls to identify any abnormalities.
When do you start the clear liquid diet before a colonoscopy?
The timing of when you need to start the clear liquid diet depends on your unique bowel prep schedule. Some general guidelines include:
- 1 day clear liquid diet – Start clear fluids after breakfast about 24 hours before your colonoscopy and continue up until 2 to 4 hours before your appointment time.
- 2 day clear liquid diet – Start clear fluids after breakfast about 48 hours before your colonoscopy. Continue clear fluids up until 2 to 4 hours before your procedure.
- 3 day clear liquid diet – Start 72 hours before your scheduled colonoscopy. Continue until you are within 2 to 4 hours of your appointment.
Follow your doctor’s specific recommendations on when to start and stop clear liquids before your colonoscopy. Consuming a clear liquid diet for longer than a day is often recommended for chronic constipation. Starting the diet 1 to 3 days beforehand ensures your colon will be clear of all solid food matter.
What can I drink to stay hydrated?
Hydration is crucial when following a liquid diet before your colonoscopy. Dehydration can cause headaches, dizziness, cramping, constipation, and impaired bowel prep. Focus on consuming at least 8 glasses or 64 oz. of clear fluids throughout the day(s) leading up to your colonoscopy.
Here are some healthy drink options to stay hydrated:
Water
Water is the best way to stay hydrated. Drink at least 8 to 16 oz. of water every 2 hours while awake on your clear liquid diet. Add lemon wedges or mint leaves for enhanced flavor if desired. Try to avoid any water additives like crystals, vitamins or flavorings that can tint the water.
Fruit Juices
Fruit juice without pulp, such as apple, white grape, strained lemonade, white cranberry, and peach provide key antioxidants, vitamins, and fluids. Avoid any juices labeled punch, fruit cocktail, red, dark, or purple colored juices. Limit juice intake to a maximum of 16 oz. per day on a clear liquid diet to avoid excess sugar.
Tea and coffee
Plain tea and coffee boost alertness. Avoid using cream, milk or any whitener. A small amount of honey, sugar or other clear sweetener is permissible. Herbal teas including chamomile, peppermint, ginger and dandelion tea can help ease digestion and bloating. Limit caffeinated drinks to 2 cups daily as caffeine acts as a diuretic.
Clear broth
Sipping on chicken, beef or vegetable broth between meals adds necessary sodium, protein and fluids when following a liquid diet. Low-sodium varieties are gentler before a colonoscopy prep. Avoid any chunky broth or broth with visible veggies, grains or meat. Stick to transparent, yellow clear broth.
Clear carbonated beverages
The bubbles in clear soda, seltzer or ginger ale can help settle an upset stomach from the colonoscopy prep. Limit carbonated drinks to 2 cups per day to avoid bloating.
Nutritional supplements
Clear nutritional shakes and supplements provide protein and key nutrients on liquid diets. Look for products labeled transparent, colorless or water-like. Avoid supplements with fruit chunks or any thick, opaque liquids. Limit high-protein shakes to once daily as too much protein can constipate.
Popsicles and gelatin
Plain popsicles and gelatin provide sweet refreshment. Look for yellow, orange and green options over purple, red or blue. Limit popsicles and gelatin to 1-2 servings daily as too much sugar can cause gas or diarrhea.
What can you eat for calories and nutrients?
While your food choices are extremely limited on a clear liquid diet, you can incorporate select foods and drinks to get calories, protein, vitamins and minerals.
Chicken or Beef broth
Sipping on warm clear broth provides sodium, protein, fluids and about 50 to 100 calories per cup. Broth fills you up and prevents hunger leading up to a colonoscopy.
Clear protein shakes
Protein shakes labeled clear, transparent or colorless supply 10 to 15 grams protein per serving. They provide around 100 calories per 8 oz. without clouding colon walls or leaving residue.
Nutritional supplement drinks
Clear nutritional beverages like Ensure Clear or Boost Breeze give 200 to 220 calories and 10 grams protein per 8 oz. serving. They provide daily vitamins and minerals when you are unable to eat solid foods before a colonoscopy.
Fruit juice and soda
An 8 oz. glass of apple juice or lemon-lime soda contains 80 to 110 calories. Juice also provides antioxidants while soda offers fluids, sodium and potassium. Limit fruit juice to 4 oz. portions diluted with water.
Gelatin and popsicles
Plain gelatin and popsicles supply 80 to 100 calories. Opt for sugar-free varieties and limit yourself to about 1 popscile or 1⁄2 cup gelatin daily to avoid excess sugar and diarrhea
Honey
1 tablespoon honey in tea, lemon water or broth offers 60 calories. Honey also coats and soothes a sore throat which can occur while fasting from solid foods during colonoscopy prep.
Sample menus for a clear liquid diet before a colonoscopy
Here are some sample clear liquid menus to follow for breakfast, lunch and dinner in the 1 to 3 days before your colonoscopy appointment:
1 Day Clear Liquid Diet
Breakfast:
- 1 cup clear apple juice mixed with 1 cup water
- 1 cup clear broth
- 1 cup clear nutritional supplement drink
- 1 cup herbal tea with honey (optional)
Lunch:
- 1 cup lemon-lime soda
- 1 cup clear broth
- 1 cup water
- 1 plain popsicle
Dinner:
- 1 cup clear fruit juice
- 1 cup clear broth
- 1 cup green gelatin
- 1 cup peppermint tea
Throughout the Day:
- Drink 8 cups (64oz) water
2 Day Clear Liquid Diet
Day 1
Breakfast:
- 1 cup clear apple juice
- 1 cup clear broth
- 1 cup water
- 1 cup clear nutritional supplement drink
Lunch:
- 1 cup lemon-lime soda
- 1 cup clear broth
- 1 orange popsicle
Dinner:
- 1 cup clear fruit juice
- 1 cup clear broth
- 1 cup green gelatin
- 1 cup chamomile tea
Day 2
Breakfast:
- 1 cup clear apple juice mixed with 1 cup water
- 1 cup clear chicken broth
- 1 cup clear nutritional supplement
Lunch:
- 1 cup ginger ale
- 1 cup beef broth
- 1 yellow popsicle
- 1 cup peppermint tea
Dinner:
- 1 cup white grape juice
- 1 cup chicken broth
- 1 cup lemon gelatin
- 1 cup chamomile tea
Throughout the Day Both Days:
- Drink 8 cups (64oz) water
3 Day Clear Liquid Diet
Day 1
Breakfast:
- 1 cup clear apple juice
- 1 cup vegetable broth
- 1 cup water
Lunch:
- 1 cup lemon-lime soda
- 1 cup clear broth
- 1 orange popsicle
Dinner:
- 1 cup white grape juice
- 1 cup clear broth
- 1⁄2 cup green gelatin
- 1 cup peppermint tea
Day 2
Breakfast:
- 1 cup apple juice mixed with 1 cup water
- 1 cup clear nutritional supplement
- 1 cup clear broth
Lunch:
- 1 cup ginger ale
- 1 cup clear broth
- 1 yellow popsicle
Dinner:
- 1 cup white grape juice
- 1 cup clear broth
- 1⁄2 cup lemon gelatin
- 1 cup chamomile tea
Day 3
Breakfast:
- 1 cup apple juice
- 1 cup clear nutritional supplement
- 1 cup chicken broth
Lunch:
- 1 cup ginger ale
- 1 cup beef broth
- 1 cup water
Dinner:
- 1 cup white grape juice
- 1 cup clear broth
- 1 cup peppermint tea
Throughout the 3 Days:
- Drink 8 cups (64oz) water daily
Shopping list for clear liquid diet before colonoscopy
Stock up on these clear liquid items and ingredients at the grocery store while prepping for your colonoscopy:
Beverages
- Water – flat, carbonated, flavored
- Clear fruit juices – apple, white grape, lemonade, cranberry
- Soda – lemon-lime, ginger ale
- Tea – chamomile, peppermint, green tea bags
- Clear broth – chicken, beef, vegetable
- Nutritional supplements – Ensure Clear, Boost Breeze
Sweets and Desserts
- Popsicles – yellow, green, orange flavors
- Gelatin – lemon, lime, orange
- Honey or sugar
- Hard candy – lemon drops, ginger candy
Seasonings
- Salt
- Pepper
- Lemon wedges
- Mint leaves
Tips for succeeding on the clear liquid diet before a colonoscopy
Here are some tips to help you stick to the clear liquid diet leading up to your colonoscopy:
- Stay hydrated – Drink at least 64 oz. of water and clear fluids spaced throughout your waking hours.
- Consume your largest volume of clear liquids earlier in the day – This gives time for fluids to pass through before overnight fasting.
- Sip liquids slowly – Gulping large amounts quickly can cause nausea, vomiting, bloating.
- Set reminders to drink – Space out alarms on your phone to remember to consume fluids.
- Opt for hot or cold liquids – Warm broth fills and satisfies. Popsicles provide sweet relief.
- Flavor liquids – Add lemon, honey, spices to enhance taste.
- Limit high sugar liquids – Too much sugar can cause diarrhea.
- Stay occupied – Distract yourself from hunger with books, movies, light walks.
- Rest and relax – Save your energy during the liquid diet days.
- Avoid solid foods – Don’t chew gum, lick hard candy or mints.
The bottom line
When preparing for a colonoscopy, following a clear liquid diet 1 to 3 days beforehand is necessary. Consuming only see-through beverages ensures your colon will be completely clean for your procedure. Stick to transparent liquids like water, clear juices and broths, avoiding any red, blue or purple colored liquids. Drink plenty of fluids, incorporate popsicles, gelatin and supplements for calories. Flavor drinks with honey, lemon and herbs for taste. Your doctor will provide your specific liquid diet start time and duration based on your health history. Refer to the shopping lists and sample clear liquid menus for guidance. Stay motivated knowing the clear liquid diet is temporary, but critical for an effective, comfortable colonoscopy.
