Preparation Instructions for Colonoscopy with HalfLytely


Prescription Medications: You may continue taking your normal medications/supplements (except blood thinners) until midnight the morning of your procedure. The morning of the procedure you may take only pain meds with a sip of water, no later than 2 hours before your procedure time. You will be home in time to take your morning meds after your procedure.

Diabetics: Test your blood sugar before you come in and bring the reading with you. For questions about your medications/insulin dosages, please contact the doctor who is monitoring your diabetes.

You should NOT plan on working, or driving, or watching small children, the entire day of your procedure, due to the sedation.

You must have someone to take you home after your procedure.

Purchase one HalfLytely colon cleansing kit from the pharmacy (you will need a prescription for this) and one 10 ounce bottle Magnesium Citrate. Baby wipes and Desitin or diaper cream can also be helpful.

One week before your colonoscopy:

Do not take any blood thinners such as aspirin, ibuprofen, naproxen or any NSAIDS (many arthritis medications are NSAIDS).

Two days before your colonoscopy:

If you tend to be constipated, or sometimes need a laxative, take two (2) tablespoons of Milk of Magnesia at 8 PM.

The day before your colonoscopy:

NO SOLID FOOD (including milk or dairy products)

  • Clear liquids only all day (see list below).
  • Avoid anything RED except cranberry juice.
  • Drink as much as you can, as clear liquids help with the prep.

At 12:00 noon:

  1. Take two (2) Dulcolax tablets (included in the kit) with any clear liquid.
    • Do not crush or chew.
    • Do not take within one (1) hr of taking an antacid.
  2. Mix solution
    • Add lukewarm water to the top line on bottle.
    • Shake to dissolve the powder (the solution will be colorless).
    • Put the solution in the refrigerator (most patients prefer drinking it cold).
    • Included flavorings may be added.

At 6:00 PM:

  1. Start to drink the HalfLytely solution.
  2. Drink one cup every 10-15 minutes until gone.
  3. If you get nauseated you can wait up to 45 minutes to take the next dose, as long as you finish in 2-3 hours (using a straw can help).
  4. Be prepared to use the facilities frequently.
  5. You may experience some discomfort such as bloating and cramping - this should improve with bowel movements.

If your bowel movements are not clear/yellow by 11:00 PM (or when you go to bed) drink a 10oz bottle of Magnesium Citrate unless you have any kidney or heart problems.

NOTHING BY MOUTH AFTER MIDNIGHT except pain meds with a sip of water if needed.


Clear liquids include:

  • Water
  • Sports drinks like Gatorade (no red)
  • Clear fruit juice (apple, white grape, or cranberry)
  • Popsicles (no sherbet or fruit bars)
  • Soft drinks (no red, yes you can have colas)
  • Clear broth or bouillon
  • Jello (no red)
  • Kool Aid or Crystal Light
  • Coffee or tea (no milk or creamer)
  • Hard candies (no red)