Like others have said, even if they haven't found the source of the reaction, you should at least have an epi-pen with you at home and in your diaper bag. Our pediatrician wrote a prescription for one for us just in case since Lucy was allergic to milk and her reaction was quite dramatic. She didn't think we'd need to use it, but said it wouldn't hurt to have it. And as others have stated, once you get the epi-pen, learn how to use it. You don't want to be fumbling about with the directions during an emergency situation. Again, this was my pediatrician's advice.