Lactulose Bristol Laboratories (Lactulose)

Lactulose acts on the gastrointestinal tract to relieve constipation and lower ammonia levels in liver disease.

• Constipation: softens stools and promotes regular bowel movements.
• Hepatic encephalopathy: reduces intestinal absorption of ammonia, helping to improve neurological symptoms.
• Prevention of hepatic encephalopathy recurrence: maintains low ammonia levels to avoid relapse in chronic liver disease patients.

• Lactulose is a synthetic disaccharide that is not absorbed in the small intestine. In the colon, bacterial enzymes hydrolyze it to short‑chain fatty acids, increasing osmotic pressure and drawing water into the lumen, which softens stool and stimulates peristalsis. The acidic environment also converts ammonia to ammonium, trapping it in the gut and reducing systemic absorption, thereby lowering blood ammonia concentrations.

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

Common Side Effects

• Abdominal cramping: mild to moderate discomfort in the abdomen.
• Flatulence: increased intestinal gas production.
• Diarrhea: loose stools, especially at higher doses.
• Nausea: feeling of sickness or urge to vomit.
• Bloating: sensation of fullness or swelling in the abdomen.
• Thirst: increased desire for fluids.

Serious or Rare Side Effects

• Severe electrolyte imbalance: abnormal levels of sodium, potassium, or chloride.
• Dehydration: excessive loss of body fluids.
• Severe abdominal pain: intense, persistent pain requiring medical attention.
• Allergic reaction: rash, itching, swelling, or difficulty breathing.

Before initiating lactulose therapy, consider the following safety measures.

• Assess renal function: ensure kidneys can handle fluid shifts.
• Monitor electrolytes: watch for sodium and potassium disturbances.
• Use caution in diabetes: lactulose contains carbohydrate that may affect glucose control.
• Avoid in intestinal obstruction: risk of worsening blockage.
• Adjust dose in hepatic impairment: liver disease may alter drug handling.
• Store at room temperature: keep in the original container, protect from moisture and direct sunlight.

Lactulose can interact with other medications and substances, requiring attention to avoid reduced efficacy or increased adverse effects.

Major Interactions (Avoid)

• Antacids containing magnesium: may increase laxative effect and cause diarrhea.
• Other laxatives (e.g., senna, bisacodyl): risk of excessive bowel stimulation and electrolyte loss.
• Antibiotics that alter gut flora (e.g., rifaximin): may diminish lactulose's conversion to acids.

Moderate Interactions (Monitor Closely)

• Diabetes medications (insulin, oral hypoglycemics): carbohydrate content may affect blood sugar.
• Mineral supplements (calcium, iron): may affect absorption or cause constipation.
• Probiotics: could modify gut bacterial activity and alter lactulose effectiveness.