Clear liquids for colonoscopy prep are any fluids you can see through. Water, broth, black coffee, tea, apple juice, gelatin, sports drinks, and certain sodas all qualify. The key rule: if you hold it up to light and can’t see through it, skip it. You’ll typically follow this diet for the full day before your procedure, and the goal is to empty your colon completely so your doctor has an unobstructed view during the exam.
The Full List of Allowed Clear Liquids
The following are all fair game during your prep day:
- Water: plain, carbonated, or flavored
- Fruit juices without pulp: apple juice, white grape juice, lemonade, fruit punch
- Broth: clear chicken broth, beef broth, bouillon, or consommé
- Coffee or tea: no milk, cream, or any type of creamer (including almond, soy, or oat milk)
- Carbonated drinks: ginger ale, Sprite, cola, root beer (color restrictions apply, see below)
- Gelatin: without fruit pieces
- Ice pops: without milk, fruit bits, seeds, or nuts
- Sports drinks
- Hard candy: lemon drops, peppermint rounds
- Honey or sugar
You can add sugar and lemon to tea. Caffeine is fine. The restriction is specifically on anything opaque: milk of any kind, cream, nondairy creamers, smoothies, protein shakes, and any juice with pulp.
Colors to Avoid (and Why)
Red, blue, and purple liquids are typically off-limits. These dyes can temporarily stain the lining of your colon the same way they stain your tongue, and that discoloration can make it harder for your doctor to spot abnormalities during the exam. This means no red Gatorade, no grape juice, no cherry gelatin, and no purple ice pops.
That said, some facilities are more relaxed about blue and green. MD Anderson Cancer Center, for example, notes that green and blue coloring won’t be confused with blood and are fine before a colonoscopy. Red is the color that consistently causes problems. Your safest bet is to stick with yellow, orange, or colorless options unless your prep instructions specifically say otherwise.
What Doesn’t Count as Clear
A few items trip people up because they seem like they should qualify. Milk, including all plant-based milks, is not a clear liquid. Orange juice with pulp is out. Tomato soup, cream-based soups, and anything with visible fat or particles don’t count. Yogurt, applesauce, and oatmeal are off the table even though they’re soft. The test is transparency, not texture.
Alcohol is also excluded. Even though beer, wine, and spirits are technically see-through liquids, alcohol worsens dehydration. Since the bowel prep itself causes significant fluid loss, adding alcohol on top of that creates a real risk of dangerous dehydration.
Why Broth and Sports Drinks Matter
A full day of clear liquids combined with a powerful laxative prep drains your body of fluids and electrolytes. Plain water alone won’t replace what you’re losing. Broth gives you sodium. Sports drinks provide electrolytes and sugar for energy. Alternating between water, broth, and sports drinks throughout the day helps you stay hydrated and feel less miserable.
Many people underestimate how much they need to drink. The prep solution itself contributes some electrolytes, but you’re still encouraged to take in as many clear liquids as you comfortably can throughout the day. If you start feeling lightheaded or weak, that’s a signal to increase your fluid intake.
Tips for Getting Through the Day
Variety makes a difference. Rotating between warm broth, cold gelatin, sweet ice pops, and plain water keeps the day from feeling monotonous. Many people find that chicken broth is the most satisfying option because it actually tastes like food. Warming it up and sipping it slowly can help with hunger.
Hard candy is an underrated option. Lemon drops or peppermint rounds give you something to taste between drinks without violating the diet. Just avoid anything with a red, purple, or blue coating.
If you drink coffee every morning, have it. Skipping caffeine on an already difficult day adds a withdrawal headache to the mix. Just drink it black or with sugar only.
Special Considerations for Diabetes
If you have diabetes, a full day on clear liquids requires extra planning. UCLA Health recommends separating your intake into carbohydrate and non-carbohydrate categories. Non-carb options you can have freely throughout the day include water, diet soda, tea, black coffee, diet gelatin, and clear broth. For energy and blood sugar maintenance, you can take in about 45 grams of carbohydrates at mealtimes from regular gelatin, juice, or sports drinks.
Check your blood sugar when you wake up and every four hours throughout the day. Before bed, if your blood sugar drops below 140 mg/dL, have 15 grams of carbohydrates from a clear juice. If you use an insulin pump or take daily injections, talk with your diabetes care team before prep day about adjusting your doses. Do not stop insulin entirely, as this creates a risk of a serious complication called diabetic ketoacidosis.
Timing of the Clear Liquid Diet
Most doctors ask you to switch to clear liquids for the entire day before your colonoscopy. That means starting when you wake up that morning, everything you consume should be transparent. Your specific prep instructions will also tell you when to stop drinking entirely, which is usually a few hours before your scheduled procedure time. Follow your doctor’s written instructions on this cutoff, since it varies by facility and by the type of sedation used.