Staceymommy,
It's my opinion that the reason lupus patients are allergic/sensitive to so many drugs is because our immune system is already so messed up that it doesn't know good from bad.
The American Lupus Foundation says that "the use of sulfa antibiotics to treat infections in people with lupus should be avoided whenever possible. Thirty percent of people with lupus are allergic to sulfa antibiotics. In addition, these types of antibiotics can: increase photosensitivity, increase skin rashes, and lower white blood cell counts."
On my mother's side of the family they tend to have thyroid problems, drug allergies and that is where the lupus connection is. My sister is allergic to penicillin, iodine and sulfa drugs. I am allergic to penicillin, iodine, cephlasporins, plaquenil, zithromax, talacen. I have yet to develop an allergy to sulfa drugs but I've decided to not push my luck and wait till I have a reaction, I just won't take them.
I bet there are a lot of others on the board who have allergies to different drugs too.