The best replacement for sulfa is sulfur.

The best alternatives to sulfa are rated as following:
★★★★★  sulfur
★★★  sulfate
★  sulfite
★  sulpha
★  sulfites
★  sulphur
★  sulfite allergy
★  penicillin
  sulfonamide allergy
  sulfonamide
  sulpher
  quinine sulfate
  sulfa
  sulfates
  sulf
  sulfonate
  cipro
  bactrim
  sulphate

Your alternative for sulfa is not listed? Suggest!
Speaking about sulfa, one probably shouldn't forget about trimethoprim.

Other search terms related to sulfa and their ratings are:
★★★★★ trimethoprim
★ trimeth
You have in mind a companion for sulfa and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of sulfa in all years. Click on graph for more.
sulfa
sulfur
sulfate