Medically reviewed by Drugs.com. Last updated on Apr 8, 2020.
(LAK tyoo lose)
Excipient information presented when available (limited, particularly for generics); consult specific product labeling. [DSC] = Discontinued product
Kristalose: 10 g (30 ea); 20 g (30 ea)
Generic: 10 g (15 ea)
Constulose: 10 g/15 mL (237 mL, 946 mL) [unflavored flavor]
Enulose: 10 g/15 mL (473 mL) [unflavored flavor]
Generlac: 10 g/15 mL (473 mL, 1892 mL) [unflavored flavor]
Generic: 10 g/15 mL (15 mL, 30 mL, 236 mL [DSC], 237 mL, 473 mL, 480 mL [DSC], 500 mL [DSC], 946 mL, 1892 mL [DSC]); 20 g/30 mL (30 mL)
Brand Names: U.S.
- Ammonium Detoxicant
- Laxative, Osmotic
The bacterial degradation of lactulose resulting in an acidic pH inhibits the diffusion of NH3 into the blood by causing the conversion of NH3 to NH4+; also enhances the diffusion of NH3 from the blood into the gut where conversion to NH4+ occurs; produces an osmotic effect in the colon with resultant distention promoting peristalsis; reduces blood ammonia concentration to reduce the degree of portal systemic encephalopathy
Via colonic flora to lactic acid and acetic acid; requires colonic flora for drug activation
Primarily feces; urine (≤3%)
Onset of Action
Constipation: Up to 24 to 48 hours to produce a normal bowel movement
Encephalopathy: At least 24 to 48 hours
Use: Labeled Indications
Constipation (Constulose, Kristalose): Treatment of constipation
Portal systemic encephalopathy (Enulose, Generlac): Prevention and treatment of portal-systemic encephalopathy (including hepatic precoma and coma)
Off Label Uses
Minimal hepatic encephalopathy
A meta-analysis and randomized controlled trials confirm the effectiveness of lactulose in the treatment of hepatic encephalopathy. The American Association for the Study of Liver Diseases guidelines for the management of hepatic encephalopathy in patients with chronic liver disease state that lactulose is generally used as initial treatment for overt hepatic encephalopathy and is recommended for prevention of recurrent episodes of hepatic encephalopathy after the initial episode.
Patients requiring a low galactose diet
Constipation: Oral: 10 to 20 g (15 to 30 mL or 1 to 2 packets) daily; may increase to 40 g (60 mL or 2 to 4 packets) daily if necessary
Portal systemic encephalopathy (PSE), prevention: Oral: 20 to 30 g (30 to 45 mL) 3 to 4 times daily; adjust dose every 1 to 2 days to produce 2 to 3 soft stools/day
Oral: 20 to 30 g (30 to 45 mL) every 1 hour to induce rapid laxation; reduce to 20 to 30 g (30 to 45 mL) 3 to 4 times daily after laxation is achieved to produce 2 to 3 soft stools/day
Rectal administration (retention enema): 200 g (300 mL) via rectal balloon catheter; retain for 30 to 60 minutes; may repeat every 4 to 6 hours; transition to oral treatment prior to discontinuing rectal administration
Overt hepatic encephalopathy (OHE) episodes, treatment: Route not specified: 16.7 g (25 mL) every 1 to 2 hours until at least 2 soft or loose bowel movements are produced daily; titrate to maintain 2 to 3 bowel movements daily (AASLD [Vilstrup 2014]).
Minimal hepatic encephalopathy (off-label use): 20 to 40 g (30 to 60 mL) daily in 2 to 3 divided doses to maintain 2 to 3 bowel movements daily for up to 3 months (Dhiman 2000; Watanabe 1997; Prasad 2007)
Refer to adult dosing.
Note: Doses in pediatric patients may be expressed in volume (mL) or weight (g); use extra precaution.
Constipation; chronic: Limited data available: Infants, Children, and Adolescents: Oral: 1 to 2 g/kg/day (1.5 to 3 mL/kg/day) divided once or twice daily (NASPGHAN [Tabbers 2014]); maximum daily dose: 60 mL/day in adults
Constipation, palliative care: Limited data available: Children and Adolescents: Oral: 2 to 30 mL every 6 to 24 hours (Johnston 2005), others have suggested 5 to 10 mL every 2 hours until bowel movement (Kliegman 2011)
Fecal impaction, slow disimpaction: Limited data available: Infants, Children, and Adolescents: Oral: 1.33 g/kg/dose (2 mL/kg) twice daily for 7 days (Wyllie 2011; Pashankar 2005)
Portal systemic encephalopathy, prevention: Oral liquid:
Infants: 1.7 to 6.7 g/day (2.5 to 10 mL/day) in divided doses; adjust dosage to produce 2 to 3 stools/day
Children and Adolescents: 26.7 to 60 g/day (40 to 90 mL/day) in divided doses; adjust dosage to produce 2 to 3 stools/day
Oral solution: May mix with fruit juice, water or milk.
Crystals for oral solution: Dissolve contents of packet in 120 mL water.
Rectal: Dilute with 700 mL of water or NS; administer as retention enema using a rectal balloon catheter; retain for 30 to 60 minutes. May repeat enema immediately if inadvertently evacuated too promptly. Cleansing enemas containing soapsuds or other alkaline agents should not be used.
Contraindicated in patients on galactose-restricted diet.
Store at room temperature; do not freeze. Protect from light. Discard solution if cloudy or very dark. Prolonged exposure to cold temperatures will cause thickening which will return to normal upon warming to room temperature.
Dichlorphenamide: Laxatives may enhance the hypokalemic effect of Dichlorphenamide. Monitor therapy
Glutamine: May diminish the therapeutic effect of Lactulose. Specifically, glutamine may diminish the ammonia-lowering effects of lactulose. Monitor therapy
Vitamin K Antagonists (eg, warfarin): Lactulose may enhance the anticoagulant effect of Vitamin K Antagonists. Monitor therapy
Frequency not defined.
Endocrine & metabolic: Dehydration, hypernatremia, hypokalemia
Gastrointestinal: Abdominal cramps, abdominal distention, abdominal distress, diarrhea (excessive dose), eructation, flatulence, nausea, vomiting
Concerns related to adverse effects:
• Electrolyte imbalance: Monitor periodically for electrolyte imbalance when lactulose is used >6 months or in patients predisposed to electrolyte abnormalities (eg, elderly, debilitated patients). Hepatic disease may predispose patients to electrolyte imbalance. Infants receiving lactulose may develop hyponatremia and dehydration.
• Diabetes: Use with caution in patients with diabetes mellitus; solution contains galactose and lactose.
• Electrocautery procedures: During proctoscopy or colonoscopy procedures involving electrocautery, a theoretical risk of reaction between H2 gas accumulation and electrical spark may exist; thorough bowel cleansing with a nonfermentable solution is recommended.
Blood pressure, standing/supine; serum electrolytes, serum ammonia; bowel movement patterns, fluid status
Pregnancy Risk Factor
Lactulose is poorly absorbed following oral administration. Treatment of constipation in pregnant women is similar to that of nonpregnant patients and medications may be used when diet and lifestyle modifications are not effective. Lactulose may be used when an osmotic laxative is needed (Body 2016; Gomes 2018; Shin 2015).
What is this drug used for?
• It is used to treat constipation.
• It is used to treat or prevent certain brain or mental problems caused by liver disease. It may be used by mouth or rectally.
• It may be given to you for other reasons. Talk with the doctor.
All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:
• Abdominal cramps
• Passing gas
WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:
• High blood sugar like confusion, fatigue, increased thirst, increased hunger, passing a lot of urine, flushing, fast breathing, or breath that smells like fruit.
• Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.
Note: This is not a comprehensive list of all side effects. Talk to your doctor if you have questions.
Consumer Information Use and Disclaimer: This information should not be used to decide whether or not to take this medicine or any other medicine. Only the healthcare provider has the knowledge and training to decide which medicines are right for a specific patient. This information does not endorse any medicine as safe, effective, or approved for treating any patient or health condition. This is only a limited summary of general information about the medicine's uses from the patient education leaflet and is not intended to be comprehensive. This limited summary does NOT include all information available about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to this medicine. This information is not intended to provide medical advice, diagnosis or treatment and does not replace information you receive from the healthcare provider. For a more detailed summary of information about the risks and benefits of using this medicine, please speak with your healthcare provider and review the entire patient education leaflet.
Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.
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- Drug class: laxatives