Kristalose (Lactulose)

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Lactulose (Kristalose) is a synthetic, non-digestible double-sugar (disaccharide) used to treat chronic constipation and a complication of liver disease.  It is formed from one molecule each of simple sugars fructose and galactose.  In patients with a history of chronic constipation, lactulose therapy increases the number of bowel movements per day.

How should it be used?

This medication is available in single dose packets (10g) or in a liquid form.

Liquid form:

  • Measure with a special dose-measuring spoon, not a regular table spoon.
  • Liquid may become slightly darkened in color, but this is a harmless effect. DO NOT take if it becomes very dark, or if it becomes thicker or thinner in texture.

Powder form:

  • Powder in the packet should be mixed with at least 4 ounces of water. You may also use fruit juice or milk.
  • If you miss taking a dose, take it as soon as you remember unless it almost time to take the next dose. Do not take extra medicine to make up for a missed dose.

It may take up to 48 hours before you have a bowel movement after taking this medicine.

Special Precautions/Instructions

Tell your doctor about all of the medications (including over the counter), vitamins, herbal products, and supplements you are taking before you start taking this medicine.

Tell your doctor if you:

  • Are diabetic because this medication contains galactose and lactose
  • Have a problem (hypersensitivity) to lactulose or any other ingredient in this medicine.
  • Are pregnant, plan on becoming pregnant, or are breastfeeding

Side Effects

Taking this medicine for the first time may cause gas (flatulence) and intestinal cramps. Taking too much of this medicine can cause diarrhea, stomach pain, hot and dry skin, confusion, uneven heart rate, extreme thirst, increased urination, leg discomfort, and muscle weakness or a limp feeling.

Contact your doctor immediately if you experience signs of an allergic reaction including:

  • Diarrhea
  • Feeling sick
  • Fever, shivering/chills, rash
  • Muscle and bone pain
  • Kidney problems (changes in the amount of urine or color of urine)
  • Tiredness, dizziness
  • Itching
  • Swelling
  • Trouble breathing

Additional side effects may be found on the drug’s website, which is listed below.

Storage Conditions

This medication should be stored at room temperature. Keep out of reach of children.


Call the national poison control center 1-800-222-1222 or 911 in the event of overdose. Symptoms of an overdose include vomiting, diarrhea, sore throat, fever, chills, and other signs of infection.

Pediatric Use

The safety and efficacy of this drug in pediatric patients have not been established.

Kristalose Ingredients

-lactulose, galactose, lactose

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