Lactulose Fresenius (Lactulose)

Lactulose is an osmotic laxative used to manage conditions related to bowel motility and ammonia accumulation.

• Constipation: facilitates bowel movements by increasing water content in the intestinal lumen.
• Hepatic encephalopathy: lowers blood ammonia levels, helping to improve neurological function.
• Prevention of hepatic encephalopathy recurrence: maintains low ammonia concentrations to reduce the risk of episodic decompensation.

• Lactulose is a synthetic disaccharide that is not absorbed in the small intestine. In the colon it is metabolized by bacterial enzymes into short‑chain fatty acids, which increase the osmotic pressure within the lumen, drawing water into the gut and softening stools. The acidic environment also converts ammonia (NH3) to ammonium (NH4+), reducing its absorption and lowering systemic ammonia levels.

Lactulose may cause a range of adverse reactions, most of which are related to its osmotic activity.

Common Side Effects

• Flatulence: increased gas production due to bacterial fermentation.
• Abdominal cramping: discomfort from rapid intestinal water influx.
• Diarrhea: loose stools when the dose exceeds individual tolerance.
• Nausea: mild stomach upset in some patients.
• Bloating: sensation of fullness or swelling in the abdomen.
• Thirst: increased fluid loss through stool.

Serious or Rare Side Effects

• Severe dehydration: excessive fluid loss leading to hypotension.
• Electrolyte disturbances: abnormal sodium or potassium levels.
• Allergic reaction: rash, itching, or swelling of the face and throat.
• Severe abdominal pain: persistent or worsening pain requiring medical attention.
• Worsening hepatic encephalopathy: paradoxical increase in neurological symptoms.

When prescribing lactulose, clinicians should consider several safety aspects.

• Assess renal function: impaired kidneys may affect fluid and electrolyte balance.
• Monitor electrolytes: watch for sodium and potassium shifts during therapy.
• Contraindicate in galactosemia: patients with this metabolic disorder should avoid lactulose.
• Use caution in pediatric patients: safety and dosing have not been fully established.
• Discontinue if severe diarrhea occurs: to prevent dehydration and electrolyte loss.
• Store at ambient temperature: keep in the original container, protect from moisture and direct sunlight.

Lactulose can interact with other medicines, altering its efficacy or safety.

Major Interactions (Avoid)

• Antidiarrheal agents (e.g., loperamide): may reduce lactulose's laxative effect.
• Mineral oil: can interfere with the absorption of other oral drugs.

Moderate Interactions (Monitor Closely)

• Broad‑spectrum antibiotics: may alter gut flora, affecting lactulose metabolism.
• Probiotics: could enhance the osmotic effect and increase gastrointestinal symptoms.
• Diuretics: may increase the risk of electrolyte imbalance when combined with lactulose.