Almost all children who develop an allergy to cow's milk do so within their first year of life. Dairy allergies are the most common food allergy for infants.
Most babies with a milk allergy will develop a tolerance by adulthood. About 5 percent will outgrow their allergy by age 4, and about 20 percent will outgrow it by age 8.
Rates of dairy allergy vary widely in different parts of the world. Studies have found these rates of milk allergy by country:
- United States: 1% to 2.5% of children under 6
- Israel: less than 1% of children
- Australia: More than 10% of one-year olds
No one is sure why there are such different rates of dairy allergy in different countries.
Dairy products may cause reactions in infants through different immune responses. Some may cause immediate symptoms while others may be delayed.
Classic (Ig-E- Mediated) Food Allergy
Symptoms of classic Ig-E mediated food allergies typically appear within 15 to 30 minutes of eating dairy products. Symptoms of food allergy in babies may be different from those of adults, but may include:
- Digestive problems
- Wheezing or difficulty breathing
- Swelling around the mouth or lips
- Anaphylaxis is possible, but very rare in infants.
About one-third of young children with eczema (atopic dermatitis) have an Ig-E-mediated food allergy. Allergy testing can help to figure out which foods may be triggers for your baby.
While some studies have shown that avoiding eggs in egg-allergic infants can improve symptoms of eczema, there have not been any studies that have shown that avoiding dairy can have the same result. Eczema may have many causes, and avoiding dairy may not be enough to improve your baby’s symptoms.
Food allergy testing may help to identify possible causes of your baby’s allergy symptoms.
Eosinophilic Gastrointestinal Disorders
Eosinophils are a type of white blood cell that typically occupy the digestive tract in low numbers. In an eosinophilic gastrointestinal disorder (EGID), these cells multiply and may attack the body when exposed to an allergy trigger.
These diseases include eosinophilic esophigitis (EoE), eosinophilic gastritis, eosinophilic gastroenteritis, and eosinophilic colitis, depending on the location of increased eosinophils.
EoE is the most common. Symptoms may include:
- Pain when swallowing
- Feeding dysfunction
- Abdominal pain
- Weight loss
- Failure to thrive.
EGIDs are complex immune reactions that are not as well studied as classic food allergies. Food allergy tests such as skin prick tests may help to identify the trigger foods for EGIDs, but they will need to be followed up with further testing such as an oral food challenge or endoscopy.
Food Protein-Induced Enterocolitis Syndrome (FPIES)
FPIES is a severe, systemic reaction to food that is not Ig-E mediated and therefore does not show up on allergy tests. It usually develops in infants within the first months of life. Symptoms include:
- Blood-streaked stools
- Shock (less common)
Infants may be formula fed or breastfed and reacting to milk proteins in breastmilk. If your infant with FPIES develops a reaction to a particular type of formula, he is at greater risk of reacting to others. Your pediatrician will most likely prescribe a hypoallergenic formula.
The only test for FPIES is a "challenge," in which the baby is given a small amount of the food thought to be causing the problem while under supervision of a doctor. Since there is a possibility of a severe reaction, this should only be done in a medical setting where help is close at hand.
Most babies will outgrow FPIES within the first two years of life.
Preventing Dairy Allergies
It may not be possible to prevent food allergies, but there are ways to lower your baby's risk of developing allergies. If your family has a history of food or environmental allergies, discuss feeding options with your allergist or pediatrician before your baby is born. Babies who are considered "at risk" for developing food allergies may be less likely to develop food allergies if they are exclusively breastfed or fed hypoallergenic infant formulas for the first 4 months of life.
There are no cures for these syndromes, so the treatment for all types of milk sensitivity is strict avoidance of dairy products. Since many infants develop milk allergies before being introduced to solid foods, your doctor may prescribe a hypoallergenic infant formula.
Many lactation consultants will suggest avoiding dairy products if your baby is fussy or gassy or has allergic symptoms such as eczema. The few studies on breastfeeding mothers with allergic babies have found that eliminating the baby’s allergens from the mother’s diet may reduce eczema symptoms. The concern about elimination diets for breastfeeding mothers is that mothers need lots of nutrients to maintain their own health while breastfeeding. If you are considering an elimination diet, talk to a dietitian about how you can continue to eat a healthy, balanced diet without dairy.
Katz, Yitzhak, et al. Early exposure to cow's milk protein is protective against IgE-mediated cow's milk protein allergy Journal of Allergy and Clinical Immunology, Volume 126, Issue 1, July 2010, Pages 77-82.e1
Osborne, Nicholas, et al. Prevalence of challenge-proven IgE-mediated food allergy using population-based sampling and predetermined challenge criteria in infants Journal of Allergy and Clinical Immunology, Volume 127, Issue 3, March 2011, Pages 668-676.e2
Katz, Y., et al. The prevalence and natural course of food protein–induced enterocolitis syndrome to cow’s milk: A large-scale, prospective population-based study Journal of Allergy and Clinical Immunology, Volume 127, Issue 3, March 2011, Pages 647-653.e3