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Can babies be allergic to breast milk?

Breast milk is the best source of nutrition for infants. It contains the ideal balance of nutrients, antibodies, and immune factors needed for a baby’s growth and development. However, in rare cases, babies may develop allergies to proteins found in breast milk.

What causes breast milk allergies in babies?

The most common allergens in breast milk are cow’s milk protein and soy. Cow’s milk and soy proteins from a mother’s diet can pass into her breast milk and trigger an allergic reaction in her baby. Other potential allergens include eggs, peanuts, tree nuts, wheat, and shellfish.

An allergic reaction occurs when the immune system overreacts to a typically harmless protein. The immune system mistakenly identifies the protein as an invader and releases antibodies and chemicals like histamine to attack it. This triggers inflammatory symptoms in the body.

What are the symptoms of breast milk allergy?

Symptoms of a breast milk allergy usually appear in babies within 1-7 days after birth. Common symptoms include:

  • Excessive crying
  • Fussiness during and after feedings
  • Gas
  • Abdominal pain and discomfort
  • Spitting up or vomiting
  • Diarrhea
  • Congestion
  • Skin rashes like eczema
  • Blood in stool

Symptoms are usually gastrointestinal but can also be dermatologic or respiratory. Some babies may even develop anaphylaxis in severe cases. If a baby has several symptoms, especially gastrointestinal issues, an allergy to breast milk should be suspected.

Who is at risk for breast milk allergies?

Babies at highest risk include:

  • Babies with a family history of allergies, especially in close relatives like parents or siblings
  • Babies with eczema, a condition linked to food allergies
  • Babies with gastroesophageal reflux disease (GERD)
  • Premature babies or babies with low birth weight

Around 0.5% of exclusively breastfed infants develop a cow’s milk allergy. The rate may be higher in babies at risk for atopy or with a family history of allergies.

How is breast milk allergy diagnosed?

A breast milk allergy can be difficult to diagnose definitively in infants. Doctors will start with a full clinical assessment of the baby’s symptoms and medical history. Diagnostic tests may include:

  • Elimination diet: The mother eliminates potential allergens like cow’s milk, soy, eggs, wheat, nuts from her diet. If symptoms improve, it indicates an allergy.
  • Oral food challenge: The baby is given small amounts of breast milk, cow’s milk formula, or whole allergens like milk or soy. Their reaction is monitored.
  • Skin prick test: Drops of the suspected allergen are placed on the baby’s skin. Allergies are confirmed if a hive develops.
  • Blood tests: A blood sample is analyzed for antibodies to common food allergens.
  • Patch test: Allergen patches are placed on the baby’s skin. A localized eczematous reaction indicates an allergy.

If breast milk allergy is confirmed, the mother will need to continue avoiding that food in her diet. Formula-fed infants would switch to an extensively hydrolyzed or amino acid-based formula.

Treatment and management

The primary treatment for breast milk allergies is to have the mother follow an elimination diet that removes the offending allergen. For cow’s milk allergy, this means avoiding all dairy products and foods containing cow’s milk.

The mother should read ingredient labels carefully to watch for hidden milk proteins like casein, whey, lactose, etc. Calcium supplementation may be needed if dairy intake is severely restricted.

If multiple allergens need to be avoided, the mother should work with a dietitian to ensure her modified diet still meets nutritional needs for breastfeeding.

In formula-fed babies, switching to a hypoallergenic formula like an extensively hydrolyzed formula or amino acid-based formula typically resolves symptoms.

Babies should be monitored closely when dietary changes are initiated. As their gut heals and the allergen is removed, symptoms should start improving within 1-2 weeks.

Medications like antihistamines may be used short-term to manage itching or hives. In severe cases, epinephrine may be prescribed to counteract anaphylaxis.

What is the long-term outlook for babies with breast milk allergy?

The prognosis for breast milk allergy is generally good. Most infants outgrow milk and soy allergies by age 1, and egg or peanut allergy by age 5. However, around 20% of cases persist into childhood.

After 12-24 months on an elimination diet, mothers can try gradually reintroducing the allergenic foods back into their diets to see if the baby tolerates them. This should be done under medical supervision.

For persistent cases, mothers may need to continue avoiding the trigger foods while nursing. Babies who remain allergic may need to avoid those foods once they start solids as well.

Can breast milk allergy be prevented?

There is no guaranteed way to prevent breast milk allergies. However, for high-risk infants some studies suggest:

  • Breastfeeding exclusively for at least 4-6 months to avoid early exposure to allergens
  • Avoiding highly allergenic foods in the mother’s diet while nursing (cow’s milk, eggs, peanuts, tree nuts, etc.)
  • Waiting until after 6 months to introduce solids to allow the gut lining to fully mature

More research is still needed to confirm specific prevention strategies. Pregnant and nursing mothers should discuss options with their doctor, especially if their child is at high risk.

Breastfeeding is still best for babies with food allergies

Despite the risk of allergies, breast milk remains the optimal nutrition for all infants, including babies with food intolerances. The antibodies in breast milk protect babies from infections and allergens when exposed. Breastfeeding promotes healthy immune system development.

For babies with confirmed food allergies, mothers should eliminate the trigger food from their diet rather than switch to formula if possible. Breast milk can be made allergen-free for most babies. Mothers should get support from healthcare providers to manage their modified diets.

Key takeaways

  • Allergies to breast milk are possible but affect less than 1% of babies.
  • Common triggers are cow’s milk and soy proteins that pass into breast milk from a mother’s diet.
  • Symptoms involve the GI tract, skin, and respiratory system appearing soon after birth.
  • Eliminating the allergenic food from the mother’s diet is the main treatment.
  • Most food allergies in babies are outgrown by age 1-5 years.
  • Breast milk remains the best food source for babies despite a small risk of allergy.