NSTK · 01.2026Independent supplement reference
NutriStack
Edition 1.0Updated July 13, 2026

Lactulose

Prescription ·Exploratory record · not publication-reviewed ·Updated July 13, 2026

A synthetic disaccharide osmotic laxative used for the treatment of chronic constipation and, at higher doses, for the treatment of hepatic encephalopathy. Lactulose is not digested by human enzymes and acts in the colon through bacterial fermentation to produce an osmotic and acidifying effect.

Evidence tier
Strong
Indexed sources
10 1992–2025
Interactions
0
Category
Prescription
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Publication status

Exploratory record, not a reviewed medical publication.

See the editorial and medical-review policies for the publication gate.

This generated database record has not completed a claim-level review by a qualified human medical reviewer. Bibliography links and evidence labels are not approval. The page remains available for reference and is excluded from search indexing.

In short

What the research says.

A quick, data-only summary. The full evidence, dosing, and sources are below.

A synthetic disaccharide osmotic laxative used for the treatment of chronic constipation and, at higher doses, for the treatment of hepatic encephalopathy. NutriStack rates the supporting evidence as strong. Common adult dosing is Constipation: 15–30 mL (10–20 g) daily; Hepatic encephalopathy: 30–45 mL three to four times daily (as prescribed by your physician), though a prescriber sets the actual dose. This profile indexes 10 sources.

What it's good for
  • Relief of chronic constipation5
  • Treatment of hepatic encephalopathy1,2
  • Reduction of blood ammonia levels
  • Safe for long-term use4
What to watch for
  • Bloating and flatulence
  • Abdominal cramping
  • Nausea
  • Galactosemia (contains galactose and lactose)
  • Patients requiring a low-galactose diet

The bottom line

Evidence rating strong. Most-documented uses: relief of chronic constipation, treatment of hepatic encephalopathy, reduction of blood ammonia levels. 10 sources indexed (1992–2025), with 0 interaction records on file.

The science

How it works, mechanistically.

Core mechanism

Passes undigested to the colon, where resident bacteria metabolize it to low-molecular-weight organic acids (lactic acid, acetic acid, formic acid). This acidification increases osmotic pressure, drawing water into the colonic lumen and softening stool. In hepatic encephalopathy, the acidic environment converts ammonia (NH3) to ammonium (NH4+), which cannot be reabsorbed, thereby reducing serum ammonia levels.

Class
Osmotic Laxative
Dosing

Dosing & protocol.

Common range
Constipation: 15–30 mL (10–20 g) daily; Hepatic encephalopathy: 30–45 mL three to four times daily (as prescribed by your physician)
Recommended form
Oral solution or powder for reconstitution

May be mixed with fruit juice, water, or milk to improve palatability; can be taken with or without food

Safety

Full safety detail.

Side effects

  • Bloating and flatulence
  • Abdominal cramping
  • Nausea
  • Diarrhea (dose-dependent)
  • Electrolyte imbalances with excessive use
  • Sweet taste may be unpalatable

Contraindications

  • Galactosemia (contains galactose and lactose)
  • Patients requiring a low-galactose diet
  • Known bowel obstruction
  • Caution in diabetes (contains small amounts of free sugars)
Sources

Sources, by evidence tier.

Numbered references. Citations throughout the page link here.

Meta-analyses & systematic reviews

5

Reference material

5
FAQ

Common questions.

Quick answers about Lactulose, drawn from the data on this page.

What is Lactulose?

A synthetic disaccharide osmotic laxative used for the treatment of chronic constipation and, at higher doses, for the treatment of hepatic encephalopathy. Lactulose is not digested by human enzymes and acts in the colon through bacterial fermentation to produce an osmotic and acidifying effect.

What is Lactulose used for?

Commonly cited benefits of Lactulose include: Relief of chronic constipation; Treatment of hepatic encephalopathy; Reduction of blood ammonia levels; Safe for long-term use. NutriStack rates the overall evidence as strong.

What is a typical dose of Lactulose?

A typical adult dose of Lactulose is Constipation: 15–30 mL (10–20 g) daily; Hepatic encephalopathy: 30–45 mL three to four times daily (as prescribed by your physician). The commonly recommended form is Oral solution or powder for reconstitution. These are general ranges, not personalized advice; confirm the right dose with a clinician.

What are the side effects of Lactulose?

Reported side effects include bloating and flatulence, abdominal cramping, nausea, diarrhea (dose-dependent), electrolyte imbalances with excessive use, sweet taste may be unpalatable. This is educational information; check with a healthcare professional before use.

How strong is the evidence for Lactulose?

NutriStack rates this as Strong, meaning multiple high-quality meta-analyses or systematic reviews converge on the same finding. Full tier criteria are at https://nutristackapp.com/methodology/evidence-tiers.

Use this with your stack

Lactulose in NutriStack.

Add it to your stack, see how it interacts with everything else you take, and get a Stack Score that updates the moment it does.

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NutriStack is an informational and organizational tool, not a medical service, and not a substitute for professional advice. Always consult a qualified healthcare professional before starting, stopping, or changing any supplement or medication.