When a breastfed baby exhibits fussiness, gas, or rashes, parents often wonder if their infant is allergic to breast milk. While this is a common concern, the term “allergic to breast milk” can be misleading. Infants are almost never truly allergic to human breast milk itself. This article clarifies what these reactions mean for infants and their parents.
Clarifying the Concept
Infants do not develop allergies to human breast milk because its natural proteins are mild and do not provoke allergic responses. The American Academy of Pediatrics states that breast milk does not cause allergic reactions in infants. Instead, infants may react to dietary proteins from the mother’s diet that pass into the breast milk. These reactions are often referred to as food protein-induced allergic proctocolitis (FPIAP) or food protein intolerances, which are distinct from true IgE-mediated allergies.
It is important to differentiate this from lactose intolerance, which is an inability to digest lactose, a sugar found in milk, due to a lack of the enzyme lactase. An allergy, by contrast, involves an immune system response to a protein. While breast milk contains lactose, reactions in breastfed infants are to foreign proteins consumed by the mother, not to the lactose or natural proteins within the breast milk.
Identifying Dietary Triggers
The reactions seen in breastfed infants are caused by proteins from the mother’s diet that are transferred into the breast milk. The most common culprits include cow’s milk protein and soy, which are common triggers for conditions like food protein-induced allergic proctocolitis (FPIAP). Other common food proteins that can cause reactions are eggs, peanuts, tree nuts, and wheat.
The presence of these proteins in breast milk can be detected within 30 minutes of the mother consuming the food, and they can linger for several hours. The severity of an infant’s reaction depends on the quantity of the offending protein the mother consumed and the infant’s individual sensitivity. While it is rare for breast milk to contain enough protein to cause a severe allergic reaction like anaphylaxis, it can contain enough to cause gastrointestinal issues.
Recognizing Infant Symptoms
Infants reacting to certain proteins in breast milk can exhibit a range of symptoms. Digestive symptoms often include frequent spitting up, vomiting, diarrhea—sometimes with visible blood or mucus—excessive gas, abdominal pain, and colic-like behaviors. These gastrointestinal issues can also manifest as poor weight gain.
Skin symptoms include eczema, which appears as dry, scaly, itchy patches, or as hives and rashes. While less common, respiratory symptoms can occur, such as wheezing, nasal congestion, or difficulty breathing. Other signs like excessive fussiness, irritability, and sleep disturbances may also suggest a reaction.
Steps for Diagnosis and Management
If an infant shows symptoms suggesting a reaction to something in breast milk, consulting a healthcare professional, such as a pediatrician or allergist, is the first step for diagnosis. The doctor may recommend tests to rule out other causes of symptoms, such as infections or other bowel issues. In cases of food protein-induced allergic proctocolitis (FPIAP), diagnosis is based on clinical symptoms and a positive response to an allergen-free diet.
A common management strategy involves an elimination diet for the breastfeeding mother, removing suspected allergens like cow’s milk and soy proteins. Symptoms improve within 48 to 72 hours of eliminating dairy, though complete resolution of symptoms may take 1 to 2 weeks. Parents should maintain a detailed log of the mother’s diet and the infant’s symptoms to help identify triggers and monitor progress. If symptoms resolve, a healthcare provider may suggest reintroducing the suspected food for a short period to confirm the diagnosis.
In rare cases, or if dietary changes are not effective, a specialized hypoallergenic formula may be recommended. Many infants outgrow these sensitivities, with about 50% of FPIAP cases resolving by six months of age and 95% by nine months.