Cow’s Milk Protein Allergy (CMPA) in Infants and Young Children

Cow’s milk protein allergy (CMPA) is the most common type of allergy in infants and young children, affecting approximately 2% of infants and up to 5% of young children. Most cases appear during the first year of life, but rarely after the age of 5.

In some cases, allergic reactions to cow’s milk proteins can even occur in exclusively breastfed newborns if the mother consumes cow’s milk, as these allergens can pass into breast milk.

Children with CMPA are also more likely to develop other food allergies to proteins found in egg white, wheat, fish, peanuts, or environmental allergens such as pollen, dust mites, and pet dander. Research has shown that CMPA is an important risk factor for allergic rhinitis, asthma, and eczema later in childhood.

Table of Contents

• What is Cow’s Milk Protein Allergy?

• How Does CMPA Manifest in Infants?

• How Does CMPA Manifest in Young Children?

• Diagnosing CMPA

• Why Does CMPA Occur?

• Risk of Developing Other Allergies

• How to Manage CMPA

• Allergy Desensitization or Vaccination

• Can CMPA Resolve on Its Own?

What is Cow’s Milk Protein Allergy?

CMPA is an immune system reaction to cow’s milk proteins such as casein, alpha-lactalbumin, and beta-lactoglobulin. The body produces specific antibodies (IgE) against these proteins, triggering an allergic response.

When IgE antibodies encounter the allergen, histamine is released, causing symptoms depending on the affected tissues.

IgE-Mediated Symptoms (Immediate, within ~2 hours)

• Hives (urticaria)

• Angioedema (swelling of the face, lips, eyelids)

• Eye itching

• Sneezing

• Runny nose

• Dry, irritating cough

• Wheezing (whistling breath sounds)

• Nausea and vomiting

• Colicky abdominal pain

Non-IgE-Mediated Symptoms (Delayed, 3–5 days)

• Eczema or skin rashes

• Diaper area redness

• Gastroesophageal reflux

• Vomiting

• Diarrhea with mucus or blood streaks

• Abdominal colic

• Constipation

• Poor growth and development

How Does CMPA Manifest in Infants?

In infants, CMPA can cause irritability, excessive crying, and feeding refusal. Other common symptoms include:

• Digestive: Colic, vomiting, diarrhea, constipation, and poor growth

• Respiratory: Runny nose, sneezing, dry cough, wheezing

• Skin: Eczema, diaper rash, angioedema

Severe cases may cause anaphylactic shock, electrolyte imbalances, or severe metabolic acidosis, which require urgent medical attention.

How Does CMPA Manifest in Young Children?

After the introduction of solid foods, CMPA in young children often causes nonspecific symptoms similar to those in infants, including digestive, respiratory, and skin manifestations.

Parents may notice changes in stool consistency—diarrhea, pasty stools, or blood streaks. Older children may experience abdominal pain, bloating, and discomfort. Growth delays or weight loss may also occur.

Diagnosing CMPA

Diagnosis is made by an allergist based on:

• Detailed medical history, including pregnancy, family allergies, and symptom onset

• Dietary history

• Diagnostic tests such as:

  • Skin prick test for IgE-mediated reactions

  • Serum-specific IgE for cow’s milk proteins

  • Complete blood count to check for eosinophilia

Elimination Diet: For non-IgE-mediated CMPA, removing dairy from the child’s diet for 2–6 weeks, followed by gradual reintroduction, helps identify the allergen.

For exclusively breastfed infants, mothers may need to eliminate dairy from their diet. If symptoms persist, other potential allergens (egg, soy) should be considered, and specialized hypoallergenic formulas may be recommended.

Why Does CMPA Occur?

Infants and young children have an immature immune system, which may mistakenly perceive certain food proteins as harmful, leading to antibody production.

Risk factors include:

• Family history of allergies (siblings or parents with food allergies)

• Atopic predisposition in the child

• Early introduction of cow’s milk, especially before 3 months of age

Research shows that 50–80% of children with CMPA have a family history of allergies.

How to Manage CMPA

The primary treatment is to avoid cow’s milk and dairy products (yogurt, cheese) and replace them with alternatives like oat milk, almond milk, or specialized hypoallergenic formulas.

Since children with CMPA may also be allergic to soy or goat milk, testing for specific IgE before choosing an alternative is recommended.

For exclusively breastfed infants, the mother should follow a dairy-free diet for at least 3 weeks to see results. Persistent symptoms may require switching to hypoallergenic or amino acid-based formulas.

Medications such as antihistamines, corticosteroids, or respiratory treatments may be prescribed depending on the severity of symptoms.

Allergy Desensitization or Vaccination

Specific allergen immunotherapy (desensitization) aims to increase tolerance by gradually introducing controlled amounts of the allergen. The process can take 3–5 years, and is more effective in children and young adults.

Desensitization is usually recommended for environmental allergens (dust mites, pollen, pet dander) rather than food allergens. Active infections, fever, cough, or wheezing are contraindications.

Can CMPA Resolve on Its Own?

CMPA often resolves as the child grows, usually by age 5, as immune tolerance develops. Persistent CMPA in adulthood is rare and often linked to an atopic predisposition or intestinal inflammation.

Over 90% of children with CMPA develop tolerance by age 6.

Prevention

To reduce the risk of CMPA:

• Follow natural feeding practices

• Use hypoallergenic formulas for mixed feeding

• Mothers should avoid allergenic foods during breastfeeding

• Introduce cow’s milk after 12 months of age

• Avoid early introduction of solid foods before 4 months

References:

• CDC Nutrition: Cow’s Milk and Milk Alternatives

• Arne Høst, Cow’s milk protein allergy and intolerance in infancy

• Italian Journal of Pediatrics, Cow's milk protein allergy in children: a practical guide

• E.I. El-Agamy, The challenge of cow milk protein allergy