When Might My Child Outgrow His Milk Allergy?

If your child has an allergy to milk, you may have heard that many children outgrow these allergies. When does this occur? And, importantly, is your child truly allergic to milk in the first place?

Outgrowing a Food Allergy to Milk - How Common and What Age?

Cow’s milk allergy is the most common food allergy occurring in young children, affecting between 2% and 7.5% of kids under age 1. Previous studies have shown that a little over half of children will outgrow milk allergy by ages 3 to 5. That means that a significant proportion of children will continue to be allergic to milk, at least until their adolescent or teenage years, and some may never outgrow their milk allergy.

Is It Really a Milk Allergy?

Your pediatrician may mention the term "allergy" without offering clarification that may help you get a better handle on exactly what your child is facing. Here are the specific types of reactions your child may have to milk:

Classic milk allergy: Classic milk allergy involves both having allergic symptoms within two hours of consuming milk and having the presence of allergic antibodies, or IgE, against various proteins in milk. Allergic symptoms can include hives, swelling, difficulty breathing, nausea/vomiting, diarrhea, and/or anaphylaxis. Presence of antibodies alone does not mean a person has an allergy.

Food protein-induced enterocolitis syndrome (FPIES): Food protein-induced enterocolitis syndrome (FPIES) is a non-IgE immune-mediated reaction that typically presents with vomiting, diarrhea and/or lethargy around 90 minutes after consuming milk or other trigger. Sometimes milk IgE is elevated but most often it is not. FPIES typically occurs in young infants and is commonly outgrown by age 3.

Lactose intolerance: Lactose intolerance is a gastrointestinal syndrome that presents with abdominal discomfort, gassiness, bloating, and/or diarrhea. It is typically caused by insufficient lactase, an enzyme that digests lactose. Replacing lactase enzyme or consuming milk products that have lactose removed, prevents symptoms. Lactose intolerance typically occurs in older children and adults and is less likely to be outgrown.

Diagnosing True Milk Allergy

The diagnosis of true milk allergy may include a combination of a careful history, physical examination, an elimination diet, skin prick tests, specific IgE measurement, and a food challenge test.

Unfortunately, the most sensitive and specific test for milk allergy is a challenge test, having your child drink milk. This involves starting with an elimination diet, followed by an oral food challenge done in an allergist's office or other healthcare environment for careful monitoring.

This is not recommended, however, for children who have had a recent anaphylactic reaction to cow's milk for obvious reasons. If skin tests and blood tests suggest a child with a previous anaphylactic reaction has outgrown the allergy, it may be considered.

Outgrowing True Milk Allergy

There are also studies that suggest outgrowing a milk allergy may not be as common as previously thought, and may occur later in childhood than expected.

For example, a 2007 study based on the most accurate definition of milk allergy found that the percentages of previously allergic children who could tolerate milk at various ages were:

• 19% by age four
• 42% by age eight
• 64% by age twelve
• 79% by age 16

Which Children are More Likely to Outgrow Their Food Allergy?

So how can you know if your child is likely to outgrow her allergy or not?

Part of the answer may depend on other allergies your child has. Studies suggest that children with allergic rhinitis (hay fever), asthma or other common food allergies may be less likely to outgrow milk allergy.

As noted under diagnosis, the most sensitive test to determine if a milk allergy is present is not a blood test, but the reaction a child has upon being challenged with the offending food. Unfortunately, some children may never outgrow their milk allergy, and their food allergy may persist into adulthood, or even indefinitely.

Coping with Milk Allergy

It can be difficult to cope with a sensitivity to milk whether it represents a true food allergy, lactose intolerance, or other causes. Because milk products are a common ingredient in many packaged foods, cooking from scratch can be a relatively easy way to avoid hidden sources of milk. Here are some tips on foods and food products to avoid on a milk-free diet.

The main treatment available for milk allergy is avoidance, although studies are looking at immunotherapy as a promising treatment option. Immunotherapy involves exposure to small amounts of the allergen to help decrease your reactivity over time.