What is the best course of action for a 2-month-old infant with a cow's milk protein allergy who is exclusively breastfed?

Management of Cow's Milk Protein Allergy in a Breastfed Infant

The mother should continue breastfeeding while eliminating milk products from her own diet to manage a 2-month-old infant with cow's milk protein allergy. 1

Understanding Cow's Milk Protein Allergy in Breastfed Infants

• Cow's milk protein allergy (CMPA) is one of the most common food allergies in infants, affecting approximately 0.5-3% of infants in the first year of life 2
• Proteins from the maternal diet, including cow's milk proteins, can transfer through breast milk in sufficient quantities to cause allergic reactions in sensitive infants 1
• Symptoms may involve multiple organ systems and can be IgE-mediated, non-IgE-mediated, or mixed 2

First-Line Management Approach

Continue Breastfeeding with Maternal Dietary Modification

• When possible, breastfeeding should be continued in infants with CMPA, which is consistent with official recommendations for infant feeding 1
• The mother should eliminate cow's milk and dairy products from her diet if the infant is symptomatic 1
• This approach preserves the numerous benefits of breastfeeding while addressing the allergic condition 1

Monitoring and Follow-up

• After maternal elimination of cow's milk products, most infants show improvement within 1-4 weeks depending on the type of allergy 2
• If the infant is thriving and remains asymptomatic after maternal dietary elimination, continued breastfeeding with the restricted maternal diet is appropriate 1
• A nutritional consultation should be considered to assist the mother with the elimination diet to ensure adequate nutrition 1

When to Consider Alternative Approaches

• If resolution of symptoms is not accomplished with maternal dietary elimination, or if the infant has failure to thrive, discontinuation of breastfeeding and introduction of a hypoallergenic formula should be considered 1
• Options for formula feeding include:
  • Extensively hydrolyzed casein-based formula (first choice) 1
  • Amino acid-based formula (for 10-20% of infants who don't respond to extensively hydrolyzed formula) 1, 3
  • Rice protein hydrolysate formulas (emerging alternative) 4, 3

Important Clinical Considerations

• Maternal elimination diets should not be overly restrictive to avoid compromising the mother's nutrition and ability to breastfeed 1
• If a maternal elimination diet is trialed, it is important to perform a rechallenge after 1-2 weeks to confirm the diagnosis before implementing longer periods of dietary restriction 1
• Goat and sheep milk are not recommended alternatives due to high protein sequence homology with cow's milk 1
• Regular soy formula is not recommended as a first-line alternative due to potential cross-reactivity (20-40% of US infants with CMPA may also react to soy) 1

Long-term Management

• Tolerance to cow's milk protein typically develops over time 2
• Periodic reintroduction should be attempted every six months after the initial one year of elimination diet 2
• Reintroduction of cow's milk protein should be done under medical supervision, especially in cases with history of severe reactions 1

By following this approach, most infants with CMPA can continue to receive the benefits of breastfeeding while avoiding exposure to the allergen through careful maternal dietary management.