Nitrofurantoin
"I was prescribed this antibiotic post op for a UTI that I developed from catheter during procedure.  Cleared the infection within 2 days, but 5 days later I developed a severe itchy all over body rash which included my eyelids being so swollen I could barely open.  Thought I was headed for ER but doctor prescribed a steroid to counteract.  Finished the week long steroid dose and still getting flare ups."