Question: I am afraid to take antibiotics after a reaction to sulfa. How do I know that another antibiotic won't cause a reaction?
Answer: If you've had a reaction to sulfa antibiotic, you've reacted to sulfonamide. There's a large number of drugs that contain sulfa that do not cross react with these sulfonamide antibiotics.
In the future, if you were to get an infection, your physician can clearly pick an alternative choice that would be safe for you to take that would be unrelated to the sulfonamide antibiotics. You don't need to be fearful of taking a new antibiotic and, in fact, not treating an infection may be life-threatening.