Elimination diets have been used for the prevention or treatment of allergic disease with the diet of the pregnant or breastfeeding mother or the child, or both, being modulated as deemed appropriate. Evidence from studies published so far suggests that dietary restrictions are in fact effective only in the treatment of specific food allergies, not in allergy prevention. An elimination diet of a child or a breastfeeding mother entails a risk to normal nutrition and growth of the child. Although studies are lacking, dietary restrictions during lactation may well be harmful also to the mother's health. Substitution of nutritionally important foods and professional guidance are necessary for the successful treatment of food allergies.