Nitrofurantoin is an antibacterial medication used to treat urinary tract infections, but it is not as effective for kidney infections. It is taken by mouth. Common side effects include nausea, loss of appetite, diarrhea, and headaches. Rarely numbness, lung problems, or liver problems may occur. It should not be used in people with kidney problems. While it appears to be generally safe during pregnancy it should not be used near delivery. While it usually works by slowing bacterial growth, it may result in bacterial death at the high concentrations found in urine. Nitrofurantoin was first sold in 1953. It is on the World Health Organization's List of Essential Medicines. It is available as a generic medication. In 2020, it was the 167th most commonly prescribed medication in the United States, with more than 3million prescriptions. Medical uses Current uses include the treatment of uncomplicated urinary tract infections (UTIs) and prophylaxis against UTIs in people prone to recurrent UTIs. Increasing bacterial antibiotic resistance to other commonly used agents, such as trimethoprim/sulfamethoxazole and fluoroquinolones, has led to increased interest in using nitrofurantoin. The efficacy of nitrofurantoin in treating UTIs combined with a low rate of bacterial resistance to this agent makes it one of the first-line agents for treating uncomplicated UTIs as recommended by the Infectious Diseases Society of America and the European Society for Microbiology and Infectious Diseases. Nitrofurantoin is not recommended for the treatment of pyelonephritis, prostatitis, and intra-abdominal abscess, because of extremely poor tissue penetration and low blood levels. Antibacterial activity Nitrofurantoin has been shown to have good activity against: E. coli Staphylococcus saprophyticus Coagulase negative staphylococci Enterococcus faecalis Staphylococcus aureus Streptococcus agalactiae Citrobacter species Klebsiella species Bacillus subtilis species It is used in the treatment of infections caused by these organisms. Many or all strains of the following genera are resistant to nitrofurantoin: Enterobacter Proteus Pseudomonas Antibiotic susceptibility testing should always be performed to further elucidate the resistance profile of the particular strain of bacteria causing infection. Special populations Pregnancy Nitrofurantoin is pregnancy category B in the United States and pregnancy category A in Australia. It is one of the few drugs commonly used in pregnancy to treat UTIs. It however should not be used in late pregnancy due to the potential risk of hemolytic anemia in the newborn. Newborns of women given this drug late in pregnancy had a higher risk of developing neonatal jaundice. Evidence of