Cow's milk protein allergy (CMPA) is an abnormal immune system reaction to proteins found in milk, primarily casein and whey. When exposed, the child's body mistakenly identifies these proteins as "foreign agents," triggering an allergic response. This condition must be distinguished from lactose intolerance, which is related to a deficiency in digestive enzymes, not an immune reaction.

Children diagnosed with cow's milk protein allergy in infancy may outgrow the condition as they get older, but regular monitoring and evaluation are still necessary. In your 14-month-old child's case, the diagnosis of allergy and the current reduction in symptoms are positive signs, yet they are not sufficient to confirm a complete resolution of the condition.

Observations show that a child's tolerance to cow's milk gradually improves over time. However, the rate of tolerance varies among children and depends on the allergy mechanism (IgE-mediated or non-IgE-mediated). Approximately 50% of children may regain tolerance during their first one to two years of life, and this percentage steadily increases with age, with most children outgrowing the allergy before 5 years old.

The reduction in your child's symptoms at this time is a positive indication, but it does not confirm complete tolerance to cow's milk protein. Some children may experience a relapse if re-exposed to cow's milk protein too early, particularly those with an allergic predisposition or a family history of allergic conditions such as asthma or atopic dermatitis.

Doctor Tan advises a patient. *Illustration: Tam Anh General Hospital*

At this stage, the most important principle remains dietary control. Children must continue to completely avoid cow's milk protein and related products, including goat and sheep milk, due to the risk of cross-reactivity. If using formula, an extensively hydrolyzed formula or amino acid formula should be maintained as directed by a doctor. For breastfed infants, the mother only needs to eliminate cow's milk protein from her diet if the child experiences symptoms related to breastfeeding; routine avoidance is not necessary if the child tolerates it well.

Furthermore, the child's tolerance should be re-evaluated at different stages. Reintroducing cow's milk to a child should not be attempted at home but must be guided by a doctor. Parents should take their child to a clinical immunologist for examination, who may consider ordering tests such as a skin prick test or specific IgE, or an oral food challenge under medical supervision to ensure maximum safety.

Parents also need to pay attention to the child's overall nutrition. Long-term elimination of cow's milk can lead to deficiencies in calcium, vitamin D, and protein if these nutrients are not adequately replaced. Therefore, you should consult with a doctor or a nutritionist to develop a suitable diet that ensures your child's complete development.

Doctor Nguyen Phuc Tan

Department of Clinical Immunology

Tam Anh General Hospital TP HCM