What is the best treatment approach for an 18-day-old infant with colic?

Treatment of Infantile Colic in an 18-Day-Old Infant

For an 18-day-old breastfed infant with colic, administer Lactobacillus reuteri (DSM 17938 or ATCC 55730) as first-line therapy, which reduces crying time by a median of 65 minutes per day. 1, 2

Initial Assessment: Rule Out Alarm Features

Before diagnosing colic, you must exclude organic causes by evaluating for the following red flags 1:

• Bilious or forceful vomiting (suggests obstruction or pyloric stenosis)
• Fever or lethargy (indicates infection or sepsis)
• Poor weight gain or feeding refusal (suggests inadequate intake or metabolic disorder)
• Abdominal distension or tenderness (may indicate surgical abdomen)
• Bloody stools (suggests milk protein allergy or intussusception)
• Hepatosplenomegaly or bulging fontanelle (indicates serious systemic disease)

If any alarm features are present, immediate evaluation for organic pathology is required before attributing symptoms to colic. 1

Treatment Algorithm by Feeding Type

For Breastfed Infants (Primary Approach)

Step 1: Probiotic Therapy

• Start Lactobacillus reuteri DSM 17938 or ATCC 55730 immediately 1, 2
• This is the only intervention with high-quality evidence showing marked reduction in crying time 1
• Critical caveat: Strain specificity matters—only these two strains have proven efficacy; generic probiotics are ineffective 1

Step 2: Maternal Dietary Elimination (if probiotics insufficient)

• Implement a 2-4 week maternal elimination diet excluding milk and eggs 1, 3
• This approach has supporting evidence in breastfed infants when probiotics alone are inadequate 1, 4
• Monitor infant weight gain closely during dietary modifications 3

For Formula-Fed Infants

Step 1: Formula Change

• Switch to an extensively hydrolyzed protein or amino acid-based formula as the first dietary intervention 1, 3
• This addresses potential milk protein sensitivity, which may contribute to colic symptoms 4
• Do not empirically switch formulas without evidence of milk protein allergy in the absence of colic 3

Universal Feeding Modifications (All Infants)

Regardless of feeding type, implement these evidence-based adjustments 1, 3:

• Reduce feeding volume while increasing frequency to prevent gastric distension and overfeeding 1
• Proper burping techniques after each feeding 3
• Keep infant upright when awake (never prone unless directly supervised) 1, 3
• Avoid seated positions immediately after feeding 3

Critical Pitfalls to Avoid

Do NOT prescribe acid suppressants (particularly proton pump inhibitors), as they have significant risks without proven benefit in colic 1. This is a common error that exposes infants to unnecessary harm.

Do NOT use anticholinergic, antidiarrheal, or opioid agents, as these may mask clinical deterioration 1. Dicyclomine, while historically used, has safety concerns and is contraindicated in infants under 6 months 5, 6.

Do NOT thicken formula in this 18-day-old infant, as this increases the risk of necrotizing enterocolitis, particularly in preterm or young infants 1.

Do NOT prescribe simethicone, as studies show conflicting or negative results with no proven efficacy 4, 6.

Monitoring and Reassessment

• Evaluate response after 2 weeks of dietary interventions 3
• If no improvement, consider referral to pediatric gastroenterology for evaluation of other causes 3
• Monitor weight gain closely to ensure the infant is thriving despite symptoms 3
• Watch for development of alarm symptoms that would require immediate re-evaluation 1, 3

Parental Counseling

Provide reassurance that colic is self-limited with no long-term adverse effects and typically resolves by 6 months of age 7, 5. Proper counseling about the benign nature of the condition is considered first-line management alongside specific interventions 6. Parents need support and validation that their infant is healthy despite the distressing crying episodes 7.