Food allergies continue to be a problem in the pediatric population and I often get calls or see a patient for an office visit with a parent who has a concern that their child "may have" reacted to something they ate. Their question is, are they allergic?
There is a great resource for physicians entitled "The Guidelines for the Diagnosis and Management of Food Allergy in the United States". Not all adverse reactions to foods are allergic and it sometimes takes a bit of "detective work", which is a good history and physical exam, to begin to determine if a child has a food allergy.
So, when a parent tells me that their child gets a rash on their chin or cheek after eating "xyz" food the questions begin. Was it the first time they had ever been exposed to that food? Describe the rash and how the child was acting? Did they have other symptoms with the rash? Was the rash just on a cheek or was it all over? Was it hives? This list of questions go on and on.
The most common food allergens are egg, milk, peanut, tree nuts, wheat, shellfish and soy. I also ask if this was a one time occurrence, and If they have tried the food again did it happen every time? Many times hard to tease out what a child has had to eat when they have a mish-mash of food on their plate and nothing is new!
Is there a family history of allergy or asthma? Does your child have eczema as well? If so there is a greater chance of developing a food allergy.
After a detailed history, and if I do think that the child has a good history for a food allergy, there are tests (skin prick and blood) that may help determine if an allergy may exist. BUT, with that being said, there are several caveats. Number one, your doctor should not test for "every" food allergen, only for the suspected food or foods, as there are many false positive tests when you just check all of the boxes for testing IGE levels for an allergy. For example, if your child eats eggs and has had no problem but the IGE level comes back a bit high for egg allergy, what does that really mean? In other words, I just test for the suspected culprit. So, I do not test for tree nuts if the parents only had concerns with a peanut product. More to come on this topic.