Nitrofurantoin
"Well like so many others I have to say I had extreme nausea for 3 days while taking this followed by a day of vomiting. I called my GP who told me to stop it immediately. I have never had a reaction to antibiotics before. On the other hand after taking just 3 doses on the first day the burning pain and need to urinate was gone! I also too 400mg ibruprofen for the flank pain. 

So yes it did work very fast at targeting my UTI symptoms which was great, but it left my lethargic, feeling terribly sick and throwing up after 3 days of doses. Worth trying if you are experiencing a severe UTI, but not as a first try!"