Active Ingredient

Lactulose

Lactulose is a type of sugar used as a laxative to treat constipation. It is also used in certain medical conditions to reduce ammonia levels in the blood.

It works by drawing water into the bowel, which helps soften stools and makes them easier to pass.

Written By Douglas C. Goldberg, MD

Reviewed By Philip Schein, MD

Last Updated 28 Nov 2025

Available Lactulose Brands

Duphalac

Strengths 100ml

Lactulose Uses

Lactulose is commonly used in the management of constipation and other specific medical conditions.

Relieving chronic constipation
Managing hepatic encephalopathy
Reducing blood ammonia levels

How Lactulose Works

Lactulose works by increasing the amount of water in the stool, making it softer and easier to pass. It is broken down in the colon into mild acids that pull water into the bowel.

This action helps to stimulate bowel movements and relieve constipation. Additionally, in certain liver conditions, it helps to reduce the absorption of ammonia, thereby lowering blood ammonia levels.

Common side effects of Lactulose

Not everyone experiences side effects with lactulose, and many side effects are mild and temporary.

Flatulence
Stomach cramps
Nausea
Diarrhea
Abdominal discomfort
Bloating

If you experience serious or persistent symptoms, contact your doctor.

Frequently Asked Questions

How long does it take for lactulose to work?

Lactulose usually starts to work within 24 to 48 hours. However, it may take a little longer for some individuals.

Can I take lactulose every day?

Your doctor will advise you on how often to take lactulose. It is important to follow their guidance.

Is lactulose safe for long-term use?

Lactulose can be used for long-term management under medical supervision. Always follow your doctor’s instructions.

Can lactulose interact with other medications?

Lactulose may interact with certain medications. Inform your doctor about all the medicines you are taking to avoid interactions.

What should I do if I miss a dose of lactulose?

If you miss a dose, take it as soon as you remember. If it’s almost time for your next dose, skip the missed dose and continue with your regular schedule.