Nitrofurantoin
"Took this for a bladder and kidney infection for 7 days, cleared up my infection and offered instant relief after 1 day. I am normally prone to gastro problems with antibiotics but didn't have any problems with thus one. The only side effect was it affected my sleep, after a few hours I'd wake up and couldn't get back to sleep every night while taking it. Also had anxiety dreams which I don't normally have."