urinary tract infection
"Used ciprofloxacin frequently for several years for chronic urinary tract infections. Ended up with painful urination frequently. After much money spent on tests for bladder cancer, I discovered that blood in the urine is a rare, but serious, side effect of Ciprofloxacin.  So all those times I thought I had a bladder infection, I had a ciprofloxacin induced condition. Blood (not usually visible to the naked eye) in urine, but makes urinating very painful nonetheless.  A word to the wise.  We consumers have to do our own research on side effects."