Responding very late....... but I wonder if this woman is not simply allergic
to citrus.  Citrus fruits (lemon, orange, grapefruit, lime) are common
allergens and also happen to be good sources of vitamin C (also called
ascorbic acid).  Strawberries (also sources of C) also cause reactions in
some people.  Does she react to sources of C like broccoli, cabbage,
potatoes, bell peppers, cantaloupe, blueberries?
Sanna James, M.S., R.D.