Walnut powder allergy

My three year old nephew has never shown signs of walnut allergies until recently.  He was helping cook a cake when he used his hands to put chopped (pre-packaged) walnuts into the cake batter. Since they were chopped there was a lot of walnut powder in the package, as well.

In a matter of minutes he was covered in a lacey rash on his hands, forearms and face.  He did not exhibit breathing problems. He was given a bath within minutes and his body cleared up.  Is it possible that he is allergic to the powder of the walnut?  Could he be allergic to the powder and not the nut?  Is it normal to show allergic reactions after having been expos.ed in the past without problems?  He was recently treated for Fifth's Disease and thought this may have had something to do with the reaction, as well?  Should I be concerned with giving walnuts as a food item?  Lots of questions. I look forward to hearing from you.

T. Levine
tarri.***@****

[National Jewish Health]

I would be concerned that your nephew’s rash was related to exposure to walnut protein, particularly if it was itchy.  If he is allergic to the powder he is likely allergic to the nut.  I think he deserves to be skin tested to walnut, but I can’t guarantee that it would be positive.  I would not feed him walnuts or pecans until he is evaluated further by a board certified allergist.

I hope that helps.

[Tammy2009]

I can only answer to part of your question.  Yes it is possible to develop allergies to something that has been normal.  Most allergies are developed over repeated exposure to the allergen.  The science behind an allergy is that you can not be allergy to something until you have been exposed to it, before that it is just a cell exposing an antibody, it must react with the particular antigen and cause an immune response.