Hi my derm gave me bactrim (sulfamethoxazole and trimethoprim) ds for my moderate but resistant acne how likely is this to cause steven jonson syndrome ?

Unlikely: Can occur but millions of doses every year and only a few cases. I would take medications as directed. You are aware of potential complications and if you develop rash stop meds and call physician.

Rare: Bactrim (sulfamethoxazole and trimethoprim) is associated with sjs, but it is still a very rare complication. Monitor for rash, and discontinue the medication and talk to your doctor if you develop a rash. Bactrim (sulfamethoxazole and trimethoprim) remains a very safe drug when used appropriately with thoughtful monitoring.