Prevention of Bladder infection
"In college I started getting urinary tract infections fairly frequently. Finally, after a handful of UTIs (treated with Cipro-allergic to Sulfa medicines), the doctor referred me to a urologist who placed me on Nitrofurantoin.  I was initially taking it every day, then just after sex or other situations which increased the likelihood of developing a UTI, and eventually I stopped taking it altogether because it had been about 5 years since I had a UTI.  Well, I woke up around 4am today with the all-too-familiar urgent need to pee.  By the time I had finished showering I was fairly certain I was developing a UTI.  I happened to still have some Nitrofurantoin on hand, I took a pill before work and my symptoms were gone in a matter of hours.  No side effects.  Yay!"