I have a preschooler who is allergic to peanuts.  We found out when she was 14 months old & given a lick of PB after  we made a sandwich.  She broke out in hives, her eyes swelled shut, and her breathing sounded funny so we rushed her to the ER.  We carry Epi's and Benadryl everywhere. She has had a few reactions where she picked up a piece of candy off the floor in a store.  She started scratching her tongue,coughing, rubbing her throat, and then violently threw up several times.  A friend ate PB and touched her and she broke out.  It is scary to think about, especially leaving your child with caregivers, church, and soon school.  We are trying to teach her awareness, and how to ask what is in everything.  For a 4 year old that can be hard. We are a military family and do not live close to family.  Our trips home to visit require us to be vigilant, and firm in explaining why some things are allowed and others aren't.  The hardest part has been explaining to my child why she can't have a treat, or cookie offered and wiping away her tears.