To determine optimal maintenance dose and to evaluation the efficacy and safety of polyethylene glycol 4000 (PEG4000) in children with chronic functional constipation.

This study enrolled 41 children with chronic functional constipation at the Konkuk university hospital August 2005, then June, 2007. Effective maintenance dose was designed as initial amount of PEG4000 that improved frequency, bowel movement, stool consistency for 2 months. Clinical outcome was analysed on the basis of defecation diary. Adverse effect was monitored clinically and biochemically.

As a whole group effective maintenance dose of PEG4000 was 0.55±0.16 g/kg/day (0.25-0.86). With respect to age, 3-5 years (0.60±0.15), 6-8 years (0.57±0.16), 9-13 years (0.44±0.14) ( P =0.024). With respect to body weight, <30 kg (0.62±0.14), ≥30 kg (0.41±0.10) ( P =0.001). One child comlained apigastric soreness on medication.

PEG4000 is effective and safe in children with chronic constipation. Initial maintenance dose of PEG4000 was 0.55 g/kg/day.