Milk allergy represents an over-reaction of the immune system to milk protein.  Approximately 2.5% of infants will have allergic reactions to cow's milk in the first 3 years of life.  Fortunately, as many as 85% of these children with outgrow milk allergy by 4 years of age.  Many children who are allergic to cow milk are also allergic to soy milk.  Symptoms of milk allergy include vomiting, diarrhea (sometimes with blood), colic, rash, and poor weight gain.  Milk allergy is often confused with other common food reactions such as lactose intolerance, food poisoning, viral infections, gastritis, GERD or vomiting.  Diagnosis of milk allergy is made by excluding other causes of milk intolerance and in some cases with allergy testing or colonoscopy.  Removal of the offending milk product and the use of hypo-allergenic milk products is often helpful.

  

What is milk allergy?

Milk allergy occurs when proteins found in milk are identified by basophils and mast cells in the gastrointestinal tract, causing them to release inflammatory proteins such as histamine.  Milk allergy is different than the more common lactose intolerance seen in older children and adults.

At which age is milk allergy most common?

Milk allergy typically occurs in the first 3 years of life.  Up to 85% of children with milk protein allergy will out-grow the problem by 4 years of age.

What are the symptoms of milk allergy?

• Vomiting
• Diarrhea (sometimes with blood)
• Colic or irritability
• Rash
• Poor weight gain

How is milk allergy diagnosed?

A physician may decide to switch to a hypo-allergenic milk formula when an infant presents with the symptoms of milk allergy.  If the infant improves significantly, further testing is typically not be necessary.  Allergy testing is sometimes helpful.  Skin prick testing or blood tests (RAST testing) may be helpful.  When bloody diarrhea is present, and symptoms do not improve with diet changes, a colonoscopy may be necessary.  Biopsies of the colon tissue can be reviewed under a microscope for features of milk allergy.

How is milk allergy treated?

Initially, treatment involves removing the suspected milk type from the diet.  This can be done by stopping the use of soy or cow milk formulas and replacing them with hypo-allergenic formulas (or hydrolysate formulas) such as Nutramigen, Alimentum or Pregestimil.  These formulas contain proteins that are partially broken down to limit allergic response.  When a child is older, milk products may be reintroduced into the diet slowly (under the supervision of a physician).

Can breastfed infants develop milk allergy?

Yes.  Generally, breastfed infants are less likely to develop allergic disease than formula-fed infants, however allergenic foods in the mother's diet may cause an allergic response in an infant.  Items like milk, peanuts, walnuts, almonds, eggs and fish may need to be removed from the mother's diet.

Can food allergy be avoided?

Some of the following may help:

• Breastfeeding mothers can avoid nuts and peanuts while breastfeeding
• Infants can be exclusively breastfed for the first 4-6 months of life
• Introduction of solid foods can be delayed until 6 months of life
• Delay introduction of whole cow's milk until 1 year of age
• Delay introduction of eggs until 2 years of age
• Delay introduction of peanuts, fish and shellfish until 3 years of age