"Bactrim was prescribed to my 3 year old for a boil. Although the boil went away after 4 doses she got a super high fever and complained of headache and was very lethargic. I called her doctor and he directed me to continue the medication for a few more days to complete a 7 day regimen. Eventually she broke out in hives head to toe and I rushed her to the emergency room. Allergic reaction to sulfa drugs."