What is the role of lactulose in treating constipation?

From the Guidelines

Lactulose is a recommended treatment for constipation, particularly when symptoms have failed to improve with fiber and over-the-counter laxatives, at a dose of 10–20 g (15–30 mL or 1–2 packets) daily, which can be increased to 40 g (60 mL or 2–4 packets) daily if needed 1.

Key Points to Consider

• Lactulose works by exerting an osmotic laxative effect in the colon to promote peristalsis, and it is approved by the FDA for the treatment of constipation 1.
• The most dramatic finding in studies using lactulose was the decrease in impactions and need for enemas in individuals receiving lactulose, highlighting its effectiveness in managing severe constipation symptoms 1.
• Common side effects of lactulose include bloating and flatulence, which are dose-dependent and may limit its use in some patients 1.
• Lactulose can be considered for use in mildly constipated, non-insulin-dependent patients with diabetes mellitus type 2, as it may not lead to an increase in blood sugar levels 1.

Important Considerations for Use

• Start with a lower dose and increase gradually as needed to minimize side effects.
• Take lactulose with a full glass of water and increase overall fluid intake while using it to enhance its effectiveness.
• If severe abdominal pain, vomiting, or symptoms persist beyond 7 days, consult a healthcare provider for further evaluation and guidance.
• For chronic constipation, lifestyle changes such as increased fiber intake, regular exercise, and proper hydration should accompany medication use to achieve optimal management of symptoms.

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) three or four times daily.
• The goal of treatment is to produce 2 or 3 soft stools daily.
• The dose may be adjusted every day or two to achieve this goal 2.

From the Research

Lactulose for Constipation

• Lactulose is a commonly used osmotic laxative for the treatment of constipation 3, 4, 5.
• A systematic review comparing lactitol and lactulose found that lactitol was comparable to lactulose in terms of efficacy, but had better acceptance by patients and fewer adverse events 3.
• Another study compared a Chinese herbal medicine (CCH1) with lactulose and found that CCH1 produced more spontaneous bowel movements and had lower laxative costs than lactulose 4.
• A literature review of lactulose and polyethylene glycol (PEG) found that PEG was more effective in many instances and should be the laxative of choice unless there are contraindications 5.
• However, lactulose may still be a viable option for some patients, particularly when other treatments are not effective or have adverse effects.

Comparison with Other Laxatives

• A study comparing senna with polyethylene glycol found that senna was more effective in treating constipation in children with anorectal malformation 6.
• A systematic review of over-the-counter therapies for chronic constipation found good evidence for the use of polyethylene glycol and senna, but insufficient evidence for lactulose 7.
• The review also found moderate evidence for the use of psyllium, magnesium salts, and stimulant laxatives, but noted that the quality of evidence was limited by methodological issues 7.

Adverse Events and Safety

• Common adverse events associated with lactulose include diarrhea, nausea, bloating, and abdominal pain 7.
• However, no serious adverse events were reported in the studies reviewed 7.
• The safety and efficacy of lactulose should be carefully considered when selecting a treatment for constipation, particularly in patients with underlying medical conditions or taking other medications.