Lactulose
Brand names: Duphalac, Lactugal
Lactulose, an osmotic laxative, used to treat constipation, which is common in pregnancy and the postnatal period, and is regarded as a suitable option in these settings.
ClinCalc Pro is rebuilding its dose data from primary open sources — the manufacturer SmPC (eMC), the WHO Model Formulary and other official references — under clinician review. This drug's structured dose is not yet published here. Confirm all doses against the product SmPC and your local formulary before prescribing.
Clinical monograph
How it works
Lactulose is a non-absorbed disaccharide fermented by colonic bacteria into organic acids that draw water into the bowel by osmosis, softening stool and stimulating peristalsis.
Prescribing in practice
- As it is not absorbed systemically it is considered suitable in pregnancy and breastfeeding, making it a reasonable first-line osmotic laxative in these groups.
- Onset of effect is gradual over a day or more rather than immediate, so expectations should be set accordingly.
- Flatulence, bloating and abdominal cramps are common, particularly when starting treatment.
Monitoring
Routine monitoring is not required; review the response and adjust the dose to produce a soft, comfortable stool.
Counselling the patient
- It may take a day or two to work, so do not increase the dose too quickly.
- Maintain a good fluid intake while taking it.
- Some bloating and wind are common at first and usually settle.
Evidence & guidelines
General prescribing guidance supports lactulose as a suitable osmotic laxative in pregnancy and breastfeeding given its lack of systemic absorption.
Reference: RCOG (2022) Obstetric pharmacology; NICE CG190; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. Monograph status: clinician-reviewed (2026-07-04).
Related
Curated clinical cross-links plus same-class fallbacks.