Lactulose

Name: Lactulose Drug Interactions
Creator: Dr. Brian Staiger, PharmD, BCPS

9 interactions 133 cited references

Also sold as: Cholac® Constilac® Syrup Constulose Constulose® Enulose Enulose® Evalose® Syrup Generlac Generlac® Heptalac® Kristalose Kristalose® Laxilose® Portalac®

About Lactulose

Lactulose is a synthetic sugar used to treat constipation and reduce ammonia levels in liver disease patients. Read the full Lactulose drug information page →

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS · Updated Aug 10, 2026 · Editorial policy · Data sources

Sources: FDA prescribing information (Structured Product Labeling), the published literature cited in each entry, DDInter 2.0 (a major open-access drug-interaction database), and legacy DrugBank interaction data distributed by the NIH's RxNav service (decommissioned in 2024) — analyzed and reviewed by our pharmacist team. How we build this library →

Most serious with: Levomethadyl Licorice

2 Major 7 Moderate

All (9) Major (2) Moderate (7)

Major

Lactulose Levomethadyl Increased risk of QT prolongation Details Lactulose Licorice Increased risk of hypokalemia Details

Moderate

Lactulose Acenocoumarol Elevated International Normalized Ratio serum values with potentiation of anticoagulation effects Details Lactulose Dicumarol Elevated International Normalized Ratio serum values with potentiation of anticoagulation effects Details Lactulose Droperidol An increased risk of electrolyte imbalance Details Lactulose Lithium Increased lithium concentrations and lithium toxicity Details Lactulose Phenprocoumon Elevated International Normalized Ratio serum values with potentiation of anticoagulation effects Details Lactulose Warfarin Coumadin Elevated International Normalized Ratio serum values with potentiation of anticoagulation effects Details Lactulose Lithium Carbonate Lithobid Increased lithium concentrations and lithium toxicity Details

Check another drug

Still have questions about this combination?

Every question gets a real answer from a licensed pharmacist — free, and usually within a day.

Ask the pharmacist

Educational information only, not medical advice. Always confirm interactions with your pharmacist or prescriber before making any change to your medications.