Lactulose Pediatric Dose — Constipation Treatment
Lactulose is a synthetic, non-absorbable disaccharide laxative that works by drawing water into the colon via osmotic action and acidifying colonic contents through bacterial fermentation. It is used in pediatric practice primarily for the management of constipation. Its non-systemic mechanism makes it suitable for a range of pediatric age groups when appropriately dosed.
Pediatric Dosing
For the treatment of constipation, the recommended lactulose dose is 1–3 mL/kg/day, administered orally in divided doses every 8–12 hours. The maximum daily dose is 60 mL/day.
- Dose: 1–3 mL/kg/day PO
- Frequency: Divided every 8–12 hours
- Maximum: 60 mL/day
Worked example: For a 10 kg child using a mid-range dose of 2 mL/kg/day: 10 × 2 mL/kg/day = 20 mL/day, divided as approximately 6.7 mL every 8 hours (or ~10 mL every 12 hours). For a 20 kg child at 2 mL/kg/day: 20 × 2 = 40 mL/day, divided as approximately 13–20 mL per dose depending on interval selected.
Indications and Clinical Context
Lactulose is indicated for the management of childhood constipation, including functional constipation, which is among the most common gastrointestinal complaints in pediatrics. It is classified as an osmotic laxative and is considered an appropriate first- or second-line agent in many institutional protocols. Its use is supported by pediatric gastroenterology guidelines for short- and longer-term management when dietary and behavioral measures are insufficient.
Clinicians should assess the underlying etiology of constipation before initiating therapy and monitor for adequate clinical response, typically defined by improvement in stool frequency and consistency. Dose titration within the recommended range should be guided by individual patient response.
Administration and Monitoring
Lactulose is administered orally and may be mixed with water, juice, or milk to improve palatability. It is available as a solution (typically 10 g/15 mL). Onset of action is generally 24–48 hours, so immediate laxation should not be expected. Clinicians should counsel families accordingly to support adherence.
- Route: Oral (PO) only per this dosing indication
- Common adverse effects: Flatulence, bloating, abdominal cramping, and nausea — particularly at higher doses
- Electrolyte monitoring: Prolonged or high-dose use may warrant monitoring for electrolyte disturbances, particularly in patients with renal or hepatic impairment
- Contraindications: Galactosemia (lactulose contains galactose); use with caution in patients requiring a low-galactose diet
- Max dose: Do not exceed 60 mL/day; consult institutional protocol for patients outside standard weight ranges
Disclaimer: This article is an educational reference summarizing standard pediatric dosing values. It is not a substitute for clinical judgment. Always verify doses against institutional protocols, the current edition of authoritative references (e.g., Lexicomp, Harriet Lane Handbook, PALS guidelines), the patient’s accurate weight, and any patient-specific factors (renal/hepatic function, allergies, comedications) before administration.