Therapeutic action

– Osmotic laxative


– Prevention of constipation in patients taking opioid analgesics (e.g. codeine, morphine)

Forms and strengths

– 10 g/15 ml oral solution

Dosage and duration

– Child under 1 year: 5 ml daily (1 tsp daily)
– Child from 1 to 6 years: 5 to 10 ml daily (1 to 2 tsp daily)
– Child from 7 to 14 years: 10 to 15 ml daily (2 tsp or 1 ssp daily)
– Child over 14 years and adult: 15 to 45 ml daily (1 to 3 ssp daily)

Start lactulose when analgesic treatment continues more than 48 hours.
Lactulose must be taken daily, until the end of the opioid treatment. Regular follow up (frequency/consistency of stools) is essential in order to adjust dosage correctly.

Contra-indications, adverse effects, precautions

– Do not administer to patients with Crohn’s disease, ulcerative colitis, intestinal obstruction, undiagnosed abdominal pain.
– May cause: abdominal discomfort, flatulence and diarrhoea.
– In the event of diarrhoea, exclude a faecal impaction and intestinal obstruction; reduce the dose.
– Pregnancy: no contra-indication
– Breast-feeding: no contra-indication


– It may take up to 48 hours, or even longer, before the treatment is effective. Lactulose is not indicated in acute constipation where a rapid result is needed.
– If necessary, lactulose may be given in combination with a stimulant laxative (e.g. bisacodyl, senna).
– The oral solution may be taken undiluted, or diluted in water.
– The treatment should be accompanied by dietary measures (fluids and fibre).
– Storage: below 25 °C. Do not store in a refrigerator (cristallisation).