Can bactrim (sulfamethoxazole and trimethoprim) cause a high fever?

Only: If you are allergic to it but you would have a rash or other symptom. It is more likely that you have a high fever from whatever you are on the Bactrim (sulfamethoxazole and trimethoprim) for!

Not likely: If you are given Bactrim (sulfamethoxazole and trimethoprim) for treatment of an infection, it is more likely that the fever you have is due to your ongoing infection. In rare cases, usually several days into taking certain antibiotics including bactrim, (sulfamethoxazole and trimethoprim) you can develop fever, rashes, join pain due to serum sickness-like syndrome, a type of delayed allergic reaction. A more severe reaction like in dress syndrome can cause fever too.