What are the symptoms of a milk protein allergy or other allergy to a mother's breastmilk in a newborn infant?

From the Guidelines

Symptoms of a milk protein allergy or other allergic reactions to components in breast milk typically include skin issues, gastrointestinal problems, respiratory symptoms, and behavioral signs. These reactions occur when proteins from the mother's diet pass through breast milk and trigger an immune response in sensitive infants, as noted in studies such as 1. The specific symptoms can include:

• Skin issues like eczema, hives, or rashes
• Gastrointestinal problems such as vomiting, diarrhea, blood in stool, constipation, or excessive gas
• Respiratory symptoms including wheezing, coughing, or congestion
• Behavioral signs like excessive crying, irritability, or poor sleep

If you suspect your baby has such an allergy, consult your pediatrician immediately, as they may recommend a trial of a maternal cow’s milk–free diet for a 1- to 2-week period, followed by rechallenge to assess whether symptom re-elicitation occurs, as suggested by 1. This elimination diet should be done under medical supervision to ensure both mother and baby maintain proper nutrition, and it's crucial to follow guidelines that prioritize the infant's health and the mother's ability to continue breastfeeding safely, as discussed in 1. Most infants with milk protein allergies outgrow them by age 3-5, but severe symptoms require prompt medical attention to prevent dehydration or poor weight gain.

From the Research

Symptoms of Milk Protein Allergy in Newborn Infants

• Symptoms of cow's milk protein allergy (CMPA) in newborn infants can be diverse and non-specific, making diagnosis challenging 2, 3
• Common symptoms include:
  • Gastrointestinal issues such as rectal bleeding, diarrhea, and vomiting 3, 4
  • Dermatological issues such as eczema and skin rashes 2, 5
  • Cutaneous issues such as hives and itching 2
  • Respiratory issues such as wheezing and coughing 3
• Non-IgE-mediated allergies can manifest as food protein-induced allergic proctocolitis (FPIAP), food protein-induced enterocolitis syndrome, and Heiner syndrome (pulmonary hemosiderosis) 3, 4
• IgE-mediated allergies can range from mild symptoms to life-threatening anaphylaxis 3

Diagnosis and Management

• Diagnosis is based on clinical observations, prick-test or patch-test results, and cow's milk-specific IgE antibody concentration 2
• A positive food challenge test usually confirms the diagnosis 2
• Excluding cow's milk from the mother's diet is the only cure when she still wants to breastfeed 2, 3
• Maternal cow's milk elimination diet is often successful in helping resolve symptoms in breastfed infants 3
• Reintroduction of cow's milk after a period of exclusion can help confirm a cow's milk allergy 3

Breastfeeding and Cow's Milk Allergy

• Cow's milk proteins can be transferred to breast milk, potentially causing allergic reactions in sensitive infants 2, 5
• Breastfeeding is still recommended, but mothers may need to eliminate cow's milk from their diet to prevent allergic reactions in their infants 2, 3
• The prognosis for infants with cow's milk allergy is good, with 80% acquiring tolerance before the age of 3 or 4 years 2