What is the recommended treatment for functional constipation in a 9-month-old infant?

Treatment of Functional Constipation in a 9-Month-Old Infant

For a 9-month-old with functional constipation, start with fruit juices containing sorbitol (prune, pear, or apple juice) and ensure adequate hydration, then escalate to polyethylene glycol (PEG) 3350 at 0.8-1 g/kg/day if dietary measures fail, with glycerin suppositories reserved for acute relief if needed. 1

Initial Non-Pharmacological Management

• Increase fluid intake to maintain proper hydration, which is foundational for managing constipation in infants 1
• Offer fruit juices containing sorbitol (prune, pear, or apple juice) to help increase stool frequency and water content—this is particularly effective in infants with constipation 1, 2
• Continue breast-feeding on demand or full-strength formula without restriction 1
• Introduce age-appropriate high-fiber foods such as fruits, vegetables, and whole grains if the infant has started solid foods 1

Common pitfall to avoid: Do not excessively thicken formula, as this may worsen constipation 2

When to Escalate to Pharmacological Treatment

If dietary modifications fail after 1-2 weeks, pharmacological intervention is warranted. The treatment approach differs based on whether fecal impaction is present.

For Constipation WITHOUT Impaction

• Polyethylene glycol (PEG) 3350 is the first-line laxative for infants 6 months and older, dosed at 0.8-1 g/kg/day 1
• The goal is to produce 2-3 soft, painless stools daily 1
• Alternative options include lactulose or lactitol-based medications, which are authorized and effective for infants under 6 months 3

For Constipation WITH Impaction

• Glycerin suppositories are the recommended first-line suppository option for acute relief, acting as a rectal stimulant through mild irritant action 1
• Alternatively, manual disimpaction may be performed following pre-medication with analgesic and/or anxiolytic 2

Critical warning: Avoid bisacodyl in infants under 6 months—there is no safety or efficacy data for this age group, and safer alternatives exist 1

Maintenance Therapy and Duration

• Maintenance therapy must continue for many months before the infant regains normal bowel motility and rectal perception 1
• Monitor treatment efficacy by stool frequency and consistency, absence of pain with defecation, and weight gain/growth parameters 1
• Using suppositories alone without follow-up maintenance therapy leads to 40-50% relapse rates within 5 years, highlighting the importance of sustained treatment 1

Common pitfall to avoid: Parents often cease treatment too soon before the child regains bowel motility and rectal perception—emphasize the need for prolonged therapy 1

Red Flags Requiring Further Evaluation

Assess for organic causes before assuming functional constipation:

• Failure to thrive or poor weight gain 2
• Abdominal distension or tenderness 2
• Constipation present since birth (consider Hirschsprung disease) 4
• Rule out hypothyroidism, hypercalcemia, hypokalemia, and diabetes mellitus 1

Special Dietary Considerations

• If cow's milk protein intolerance is suspected in formula-fed infants, consider a 2-4 week trial of extensively hydrolyzed or amino acid-based formula 2
• For breastfed infants with true constipation (rare), consider a 2-4 week maternal elimination diet restricting milk and eggs 2

Monitoring for Treatment Complications

Watch for these warning signs that require immediate evaluation and potential cessation of PEG treatment:

• Rectal bleeding 1
• Nausea, bloating, cramping, or abdominal pain 1
• Diarrhea 1

Evidence Quality Note

The strongest evidence supports PEG as first-line therapy for infants ≥6 months, with lactulose/lactitol for younger infants. 1, 3 While fruit juices are widely recommended, the evidence is more limited but supports their use as an initial conservative measure. 1, 2 The approach prioritizes starting with the least invasive interventions and escalating systematically based on response.