How to tell if my 9 month old has a food allergy?

Watch for symptoms : Food allergies can lead to rashes, vomiting, diarrhea, and, sometimes, life-threatening respiratory distress as is true for some with severe nut allergies. Best to talk with the baby's doctor about your concerns, and see if a consultation with an allergist is in order. In the meantime, if you see a particular pattern as described with certain foods, best to avoid them. Hope this is helpful.