If my nephew is allergic to lemon, should i assume he can't have citric acid? thank you!

Lemon: Define the reaction please? It is very rare that someone becomes allergic to lemon.

No: Citric acid is found in many foods especially fruits. The allergy to Lemons has to do with the specific proteins that trigger a cellular response from the body found in lemons. There may be cross reaction with other similar friuts and therefore he may need to have specific patch or skin testing in order to make sure he's not allergic to other kinds of fruits.