Hypoallergenic Follow-up Formula Based on Cows Milk for Infants at Risk of Allergy - Fortified with Iron. Hypoallergenic follow up formula is designed for infants at risk of developing an allergy from 6 to 12 months as the liquid part of the diet during and after weaning, in addition to other foods. It is not to be used as a breast milk substitute during the first 6 months of life. If your baby already has a declared allergy to cows milk protein, do not use NAN® H.A. 2 without asking your doctor. The introduction of any other formula, or cows milk, must only be carried out under medical supervision.