lactulose (Constulose, Enulose, Generlac, Cholac, Constilac)

  • Pharmacy Author:
    Omudhome Ogbru, PharmD

    Dr. Ogbru received his Doctorate in Pharmacy from the University of the Pacific School of Pharmacy in 1995. He completed a Pharmacy Practice Residency at the University of Arizona/University Medical Center in 1996. He was a Professor of Pharmacy Practice and a Regional Clerkship Coordinator for the University of the Pacific School of Pharmacy from 1996-99.

  • Medical and Pharmacy Editor: Jay W. Marks, MD
    Jay W. Marks, MD

    Jay W. Marks, MD

    Jay W. Marks, MD, is a board-certified internist and gastroenterologist. He graduated from Yale University School of Medicine and trained in internal medicine and gastroenterology at UCLA/Cedars-Sinai Medical Center in Los Angeles.




  • Oral or rectal solution: 10 mg/15 ml
  • Powder for solution (single dose packets): 10 and 20 g.

STORAGE: Lactulose products should be stored at room temperature, between 15 C and 30 C 59 F and 86 F).


For the treatment of constipation: The usual adult dose is 10 to 20 g of lactulose daily. The dose may be increased to 40 g daily if necessary. Twenty-four to 48 hours may be required to produce a normal bowel movement.

For the treatment of hepatic encephalopathy: The usual starting dose is 30-45 ml (20-30 g of lactulose) by mouth every hour to induce rapid defecation. After defecation occurs the dose is reduced to 20-30 g 3-4 times per day and adjusted to produce 2-3 soft stools per day.


Antacids increase the colon pH and may interfere with the way lactulose works. Separating the administration of antacids and lactulose may prevent this interaction.

Antibiotics kill bacteria including gut bacteria that live in the colon. Colonic bacteria help to transform lactulose into the active drug that produces the desired treatment results. Therefore, combining lactulose with some antibiotics may reduce the effectiveness of lactulose treatment.

PREGNANCY: Lactulose has not been adequately evaluated in pregnant women. Lactulose may be used during pregnancy if the potential benefits of treatment outweigh the potential risks to the unborn baby.

NURSING MOTHERS: It is not known whether lactulose is secreted in human milk or cause harm to the nursing infant.

REFERENCE: FDA Publishing Information

Medically Reviewed by a Doctor on 9/22/2015

Quick Guide19 Constipation Myths and Facts

19 Constipation Myths and Facts
FDA Logo

Report Problems to the Food and Drug Administration

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.

RxList Logo

Need help identifying pills and medications?

Use the pill identifier tool on RxList.

Subscribe to MedicineNet's Newsletters

Get the latest health and medical information delivered direct to your inbox!

By clicking Submit, I agree to the MedicineNet's Terms & Conditions & Privacy Policy and understand that I may opt out of MedicineNet's subscriptions at any time.

Health Solutions From Our Sponsors