Email me (click the envelope under my name at the left) and I will send you a more comprehensive list of sulfite-containing foods.
But sulfites can be in sprays (pesticides, fertilizers, etc.) and stuff put on foods that are not labeled.
And it sounds as if her reactions can be triggered by very small amounts of sulfites, much like mine.
I too get the hours of purging...but no hives. Benadryl does help.
Here's what else helps me:
As soon as I start to recognize the sulfite reaction symptoms (for me, this is neck/head pressure, light-headedness and shaking chills, which preceeds the anaphylaxis by mere minutes....), I take a huge dose of Vitamin B12 spray (methylcobolamin), and an extra dose of Claritin. I also try to get a Vitamin B12 shot, since I don't absorb B12 sublingually or orally very well.
As prevention, I take 1000mcg Molybdenum every 3 days, plus the molybdenum that is in my multivitamin every day. And I get weekly Vitamin B12 shots, and take B12 spray sublingually with each meal.
Molybdenum and Vitamin B12 are needed for the enzyme that converts sulfites into sulfates. Sulfites are toxic to the body but sulfates usually aren't (unless you're allergic to sulfates too).
I also have similar reactions to sulfur containing foods such as broccoli or cabbage.
Eating a low-sulfite diet also helps. I find I also have to avoid meat and eggs, because the sulfur amino acids are also turned into sulfites by the digestion/metabolism process. I'm ok with milk in moderation, but some others with sulfite sensitivity can't do milk.
Be aware that it is the total amount of sulfites one has been exposed to within the previous 48 hours that determines one's tolerance threshold. So for example, eating a food containing sulfites once may be fine, but if another food containing sulfites is eaten within 48 hours of the first, then a reaction may occur.
Chronic Lyme, Bart., Gluten & Sulfite Sensitivity, Many Food/Inhalant/Medication/Chemical Allergies & Intolerances, Asthma, Gut dysmotility & non-specific inflammation, Lupus, Osteoporosis, etc.; G-Tube
Meds: Flagyl, Domperidone, Claritin, Andrographis & other herbs, homeopathy, supplements, etc.