Aim  To compare the therapeutic effectiveness and tolerability of low daily doses of polyethylene glycol 4000 vs. lactulose in the treatment of neurogenic constipation in children with myelomeningocele.

Methods  Sixty-seven children with chronic neurogenic constipation were randomized allocated to receive either polyethylene glycol 4000 (0.50 g/kg) or lactulose (1.5 g/kg) for 6 months. Patients or their parents reported frequency and modality of evacuation and side effects on a diary card. Primary outcome was bowel frequency ≥3/week, and the second one was side effects at the end of treatment.

Results  Complete remission of constipation was reported by a significantly (P < 0.01) higher number of patients treated with polyethylene glycol compared with lactulose. At the end of the study, 46% patients of polyethylene glycol group and 22% of the lactulose group were asymptomatic. Compared with lactulose, patients treated with polyethylene glycol reported higher bowel frequency (5.1 vs. 2.9 bowel movements/week, P < 0.01) and reduction of encopresis. Neither lactulose nor polyethylene glycol caused clinically-significant serious side effects and palatability was similar.

Conclusions  Polyethylene glycol 4000 compared with lactulose provided a higher success rate, without significant side effects, for the treatment of constipation in myelomeningocele children.