The 2020 USDA Dietary Guideline Report recommends, “introducing peanut and egg in an age-appropriate form, in the first year of life (after age 4 months) may reduce the risk of food allergy to these foods.” In addition to the USDA, the American Academy of Pediatrics (AAP), and the National Institutes of Health (NIH), recommend starting early allergen introduction as early as 4 months, as do similar guidelines in England, Canada, and Australia. Read more about the new medical guidelines here.
The earlier you can start introducing allergenic foods like egg and milk, the better. Most food allergies develop between 4 to 6 months of age, making this a critical window to train your baby's immune system. While early allergen introduction can be effective up until 12 months old, it's important to start as early as possible because once a food allergy develops, there is no cure.
Some parents are fearful of a severe allergic reaction occurring during early allergen introduction, however, in the 3 clinical trials where over 2,000 infant participants, no severe reactions or hospitalizations were reported. Anaphylaxis, or a severe allergic reaction, is much less common in babies, which is why the earlier you begin, the better. "Babies have the fewest severe allergic reactions of any age group, with the severity of allergic reactions increasing as the child gets older," - Dr. Spergel, Chief of Allergy Section at Children's Hospital of Philadelphia (CHOP).
The key takeaway is that the longer you wait to start feeding allergens to your baby, the more likely they are to have a more severe reaction.