My son has developed an allergy where he breaks out in hives all over his body and at times has had swollen lips. We think it is food related but cannot say for sure what food. He is on medication, not sure what the name of the med. Is, but it is effective. We would like to find out what is causing the rash and swollen lips. Any idea?

You go to the doctor for an allergy test.

He could try eliminating different food groups for awhile. By process of elimination and keeping track of what he ate when he got the hives should give him a good idea of what it could and could not be.
Citrus fruit use to cause my sister to break out in hives.