Description and Brand Names

Drug information provided by: Merative, Micromedex®

US Brand Name

  1. Cholac
  2. Constilac
  3. Constulose
  4. Enulose
  5. Generlac
  6. Kristalose

Canadian Brand Name

  1. Acilac
  2. Alpha-Lac
  3. Cephulac
  4. Chronulac
  5. Lactulax
  6. Pms-Lactulose
  7. Rhodialax
  8. Rhodialose

Descriptions


Lactulose is used to treat constipation. It helps increase the number of bowel movements per day and the number of days on which bowel movements occur in patients with a history of chronic (long-lasting) constipation.

This medicine is available only with your doctor's prescription.

This product is available in the following dosage forms:

  • Syrup
  • Powder for Solution
  • Solution

Before Using

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For this medicine, the following should be considered:

Allergies

Tell your doctor if you have ever had any unusual or allergic reaction to this medicine or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.

Pediatric

Appropriate studies have not been performed on the relationship of age to the effects of lactulose in the pediatric population. Safety and efficacy have not been established.

Geriatric

No information is available on the relationship of age to the effects of lactulose in geriatric patients.

Breastfeeding

There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.

Drug Interactions

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

  • Droperidol
  • Levomethadyl
  • Licorice

Using this medicine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

  • Acenocoumarol
  • Dicumarol
  • Lithium
  • Phenprocoumon
  • Warfarin

Other Interactions

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.

Other Medical Problems

The presence of other medical problems may affect the use of this medicine. Make sure you tell your doctor if you have any other medical problems, especially:

  • Diabetes—Use with caution. May make this condition worse.
  • Low lactose or galactose diet—Should not be used in patients who follow this diet.
  • Medical tests or surgery on your colon or rectum (eg, colonoscopy, proctoscopy)—Patients undergoing these procedures should have a thorough bowel cleansing with another medicine (eg, non-fermentable solution).

Proper Use

Take this medicine exactly as directed by your doctor. Do not take more of it, do not take it more often, and do not take it for a longer time than your doctor ordered.

To use the oral liquid:

  • Measure the medicine with a marked measuring spoon, oral syringe, or medicine cup.
  • You may mix it with fruit juice, water, or milk.

To use the powder for solution: Mix the entire contents of the packet in half a glass (4 ounces) of water until solution is colorless to a slightly pale yellow color.

It may take 24 to 48 hours before you have a normal bowel movement.

Dosing

The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

  • For constipation:
    • For oral dosage form (powder for solution):
      • Adults—10 to 20 grams (g) per day. Your doctor may increase your dose to 40 g per day if needed.
      • Children—Use and dose must be determined by your doctor.
    • For oral dosage form (solution):
      • Adults—15 to 30 milliliters (mL) or 1 to 2 tablespoons per day. Your doctor may increase your dose to 60 mL per day if needed.
      • Children—Use and dose must be determined by your doctor.

Missed Dose

If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.

Storage

Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.

Keep out of the reach of children.

Do not keep outdated medicine or medicine no longer needed.

Ask your healthcare professional how you should dispose of any medicine you do not use.

Precautions

It is very important that your doctor check your progress after taking this medicine. This will allow your doctor to see if the medicine is working properly.

Call your doctor right away if you have severe diarrhea.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

Side Effects

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur:

Incidence not known

  1. Confusion
  2. decreased urine
  3. dizziness
  4. dry mouth
  5. fainting
  6. fast or irregular heartbeat
  7. increased thirst
  8. irritability
  9. lightheadedness
  10. loss of appetite
  11. mood changes
  12. muscle pain, cramps, or twitching
  13. nausea or vomiting
  14. numbness or tingling in the hands, feet, or lips
  15. restlessness
  16. seizures
  17. severe diarrhea
  18. swelling of the feet or lower legs
  19. trouble breathing
  20. unusual tiredness or weakness

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

Incidence not known

  1. Bloated
  2. excess air or gas in the stomach or intestines
  3. full feeling
  4. passing gas
  5. stomach or intestinal cramps

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

Portions of this document last updated: Feb. 01, 2024

Original article: https://www.mayoclinic.org/drugs-supplements/lactulose-oral-route/side-effects/drg-20528356