Sulfamethoxazole / trimethoprim
"My son took this medicine for about a week, he ended up having a severe reaction to it that put him in the hospital for 3 days.  He got a red, itchy skin rash all over his torso about the 8th day of taking it, he stopped taking it at that point and got a prescription for Prednisone from prompt care. Two days later he woke up and his eyes were swollen, the day after that he woke up and his entire face was swollen, we went back to prompt care and they transferred us to the Emergency room.  The hospital admitted him and kept him for 3 days because his reaction was so bad. All this just happened 2 weeks ago and his rash is just now starting to go away but now his skin is peeling and scarred.  It was a horrible and scary experience."