Cow’s Milk Protein Allergy: What Parents Need to Know

When a pediatrician mentions a “cow’s milk protein allergy,” many parents feel confused — and worried. Milk is one of the first foods introduced in infancy, and hearing that it may cause harm can be overwhelming.

Cow’s milk protein allergy (CMPA) is one of the most common food allergies in babies and young children. It occurs when the immune system reacts abnormally to proteins found in cow’s milk, treating them as a threat.

What Causes Cow’s Milk Protein Allergy?

CMPA happens when a child’s immune system mistakenly identifies milk proteins — such as casein or whey — as harmful. This immune response can trigger a range of symptoms, which may appear minutes, hours, or even days after consumption.

Common Signs and Symptoms

• Persistent vomiting or reflux
• Chronic diarrhea or constipation
• Blood or mucus in the stool
• Skin reactions such as eczema or hives
• Excessive crying, irritability, or colic-like behavior
• Poor weight gain or growth delay

How Is CMPA Diagnosed?

Diagnosis is based on clinical history, symptom patterns, and response to an elimination diet. In some cases, allergy testing or supervised food challenges may be required.

How to Protect Your Child

Managing CMPA involves strict avoidance of cow’s milk proteins and careful label reading. Milk derivatives can appear under many names in processed foods, formulas, medications, and even supplements.