Babies who show signs of allergies or come from allergic families are those at greatest risk of having allergic reactions to any milk protein, soy protein, egg, wheat, fish and peanuts. Those foods are better left to be tried after the age of one year in such children. If there is a family history in either parent or sibling of allergies to these substances then the baby has a high risk of being allergic too, and the family history should be heeded before choosing a time to introduce these foods. Eggs are such convenient nutritious food that they should be introduced if there are no risk factors around the seventh month in the same way that other foods are introduced - one teaspoon the first day, a few the next and then continue feeding if there are no problems, but then wait at least three days before trying another new food. Allergies sometimes show up at the first feed, but it may also be on the second or third feeding that reactions may occur.
Fish can cause reactions for two possible reasons.
It can cause true allergic reactions or reactions from the natural chemical content present in all but the freshest of white-flesh fish. Without a history of risk factors, sometime around ten months is a time to introduce boneless fish. The natural chemicals in tasty fish, such as salmon or tuna, are similar to those in cheese and chocolate, and these are best avoided until well into the second year. Peanuts are best avoided in children until seven years of age. In those without allergy risk factors, only smooth peanut butter is appropriate in the smallest amount in a sandwich.