From the Guidelines
The recommended dose of lactulose for constipation is 10-20 g (15-30 mL or 1-2 packets) daily, with the option to increase to 40 g (60 mL or 2-4 packets) daily if needed, as stated in the 2023 American Gastroenterological Association-American College of Gastroenterology clinical practice guideline 1. When initiating lactulose therapy, it is essential to start with a lower dose and adjust as needed to minimize side effects such as bloating and flatulence.
- Key considerations for lactulose use include:
- Dosage: 10-20 g (15-30 mL or 1-2 packets) daily, with possible increase to 40 g (60 mL or 2-4 packets) daily if needed 1
- Administration: Take with water or juice to improve taste, and increase fluid intake throughout the day
- Side effects: Bloating, gas, and abdominal cramps, especially initially, with diarrhea as a potential consequence of excessive dosing
- Long-term use: Can be used for longer periods than stimulant laxatives, but persistent constipation requiring regular use should prompt medical evaluation to address underlying causes Lactulose works as an osmotic laxative, drawing water into the intestines and softening stool, with effects usually beginning within 24-48 hours 1.
- Important patient considerations include:
- Monitoring for side effects and adjusting the dose accordingly
- Increasing fluid intake to help prevent dehydration
- Regular medical evaluation if constipation persists or worsens despite lactulose use The use of lactulose can be considered if symptoms of constipation have failed to improve with fiber and over-the-counter laxatives, and individuals do not experience significant bloating or abdominal pain with lactulose use 1.
From the FDA Drug Label
The usual adult, oral dosage is 2 to 3 tablespoonfuls (30 mL to 45 mL, containing 20 grams to 30 grams of lactulose) three or four times daily. The dosage may be adjusted every day or two to produce 2 or 3 soft stools daily The recommended dose of lactulose for constipation in adults is 2 to 3 tablespoonfuls (30 mL to 45 mL), containing 20 grams to 30 grams of lactulose, taken three or four times daily. The dose may be adjusted to produce 2 or 3 soft stools daily 2.
- Key considerations:
- Initial dose: 2 to 3 tablespoonfuls (30 mL to 45 mL)
- Frequency: three or four times daily
- Adjustment: every day or two to produce 2 or 3 soft stools daily
From the Research
Lactulose Dosage for Constipation
The provided studies do not specify the exact dosage of lactulose for constipation. However, they do discuss the effectiveness of lactulose as a treatment option for constipation.
Effectiveness of Lactulose
- Lactulose is considered a subsequent treatment option for chronic constipation if fiber is not successful or tolerated 3, 4.
- Osmotic laxatives, such as lactulose, are effective and safe for both long and short term treatment of pediatric functional constipation 5.
- Lactulose has been shown to be more effective than "irritant" laxatives in treating chronic constipation, with a persistent "carry-over" effect 6.
- A study comparing lactulose to polyethylene glycol found that lactulose resulted in a mean stool frequency of 0.9 bowel movements per day, compared to 1.3 bowel movements per day with polyethylene glycol 7.