Nitrofurantoin is used to treat or prevent certain urinary tract infections. This medication is an antibiotic that works by stopping the growth of bacteria. It will not work for viral infections (e.g., common cold, flu). Unnecessary use or overuse of any antibiotic can lead to its decreased effectiveness. Nitrofurantoin should not be used in children less than one month of age due to the risk of a certain blood problem (hemolytic anemia).