What formula should be given to a healthy, breastfeeding infant less than 6 months old with a cow's milk protein allergy who develops urticaria after introducing cow's milk-based formula?

Formula Selection for Infant with Cow's Milk Protein Allergy

An extensively hydrolyzed formula (eHF) should be given as first-line treatment for this infant with confirmed cow's milk protein allergy presenting with urticaria. 1, 2

Primary Recommendation

Extensively hydrolyzed formula (eHF) of cow's milk protein is the first-line treatment with demonstrated efficacy of 80-90% in infants with cow's milk protein allergy. 1 This recommendation is supported by the European Society for Pediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) and the American Academy of Pediatrics. 1, 2

• The infant should be switched from cow's milk-based formula to eHF immediately given the confirmed allergic reaction (urticaria). 1
• eHF contains proteins that have been enzymatically broken down to reduce allergenicity while maintaining nutritional adequacy. 3, 4
• Clinical trials demonstrate that eHF is tolerated by at least 90% (with 95% confidence) of infants with documented cow's milk protein allergy. 3, 4

When to Escalate to Amino Acid Formula

Switch to an amino acid-based formula (AAF) if symptoms are life-threatening, severe, or do not resolve after 2-4 weeks of eHF treatment. 1, 2

• AAF represents the most hypoallergenic option available and should be used for infants who fail eHF therapy. 1, 2
• Since this infant presented with urticaria (an IgE-mediated reaction) but not anaphylaxis, starting with eHF is appropriate. 5
• Monitor closely for symptom resolution within 72-96 hours to 1-2 weeks. 1

Formulas to Avoid

Do NOT use soy formula as a first-line alternative. 1, 2

• Soy formula has significant cross-reactivity affecting 20-40% of infants with cow's milk protein allergy. 1, 2
• Soy may only be considered for infants >6 months after establishing tolerance by clinical challenge. 1, 5
• For this infant under 6 months of age, soy is contraindicated as initial therapy. 5

Do NOT use partially hydrolyzed formulas. 2

• Partially hydrolyzed formulas are inadequate for treatment of confirmed cow's milk protein allergy. 2
• These formulas retain sufficient allergenicity to trigger reactions in sensitized infants. 3

Do NOT use goat's milk or sheep's milk formulas. 1

• These alternatives have high protein homology with cow's milk and will likely cross-react. 1

Breastfeeding Considerations

Since the infant is breastfeeding, the mother should continue breastfeeding with complete elimination of all cow's milk and dairy products from her diet. 1

• Cow's milk proteins transfer through breast milk in sufficient quantities to cause allergic reactions. 1
• The mother must eliminate all sources including milk, cheese, yogurt, butter, and hidden sources in processed foods. 1
• Improvement typically occurs within 72-96 hours to 1-2 weeks of strict maternal dietary elimination. 1
• Consultation with a registered dietitian is essential to ensure nutritional adequacy, particularly calcium supplementation. 1

Critical Monitoring Requirements

All children with food allergy require nutritional counseling and regular growth monitoring. 1

• Monitor weight, length, and head circumference at regular intervals. 1, 2, 4
• Children with milk allergy are at risk for inadequate calcium and vitamin D intake. 1
• If symptoms persist despite eHF for 2-4 weeks, escalate to AAF rather than continuing ineffective therapy. 1, 2

Common Pitfalls to Avoid

• Do not delay switching to amino acid formula if the infant has failure to thrive or severe symptoms that persist despite eHF. 1
• Do not use regular soy formula as first-line treatment due to significant cross-reactivity risk. 1, 2
• Do not discontinue breastfeeding prematurely when maternal elimination diet can effectively manage symptoms. 1
• Do not empirically switch between multiple formulas without recognizing the pattern of intolerance. 2