What is the recommended dose of Macrobid (nitrofurantoin) for a 16-year-old female with an uncomplicated urinary tract infection (UTI)?

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Last updated: June 13, 2025View editorial policy

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From the Guidelines

For a 16-year-old female with an uncomplicated urinary tract infection, the recommended dose of Macrobid (nitrofurantoin) is 100 mg taken orally twice daily for 5 days. This dosing is appropriate for adolescents and adults with normal kidney function, as supported by the most recent guidelines from the American College of Physicians 1. The medication should be taken with food to improve absorption and reduce stomach upset. It's essential to complete the full course of treatment even if symptoms improve before the medication is finished. Patients should drink plenty of water while taking Macrobid to help flush the urinary system. Nitrofurantoin works by concentrating in the urine where it inhibits bacterial cell wall synthesis and disrupts bacterial metabolism, making it effective against many common UTI-causing organisms like E. coli. Common side effects may include nausea, headache, or urine discoloration. If the patient experiences severe side effects such as difficulty breathing, chest pain, or signs of an allergic reaction, they should seek immediate medical attention. The choice of nitrofurantoin for 5 days is in line with the best practice advice for uncomplicated cystitis, which also includes options for trimethoprim-sulfamethoxazole for 3 days or fosfomycin as a single dose 1. However, the most recent and highest quality study supports the use of nitrofurantoin for 5 days as a recommended treatment option 1.

From the Research

Dosage Information

  • The recommended dose of Macrobid (nitrofurantoin) for a 16-year-old female with an uncomplicated urinary tract infection (UTI) is not explicitly stated in the provided studies.
  • However, the studies suggest that nitrofurantoin is a suitable treatment option for uncomplicated UTIs, especially given its low frequency of utilization and high susceptibility to common UTI pathogens 2.
  • The American Academy of Pediatrics recommends nitrofurantoin as a first-line treatment for uncomplicated UTIs in children, but the dosage is not specified in the provided studies.

Treatment Considerations

  • The selection of antimicrobial therapy for UTIs should consider factors such as pharmacokinetics, spectrum of activity, resistance prevalence, potential for adverse effects, and duration of therapy 3.
  • Nitrofurantoin is considered a reasonable alternative to trimethoprim-sulfamethoxazole and fluoroquinolones for empirical treatment of uncomplicated UTIs, especially given the current prevalence of antibiotic resistance among community uropathogens 4.
  • Clinical risk scores can be used to estimate the risk of nonsusceptibility to nitrofurantoin and other antibiotics, and to guide empiric treatment selection for adult outpatients with complicated UTIs 5.

Study Limitations

  • The provided studies do not specifically address the recommended dose of Macrobid for a 16-year-old female with an uncomplicated UTI.
  • The studies are focused on the treatment of UTIs in general, and do not provide detailed dosage information for specific patient populations 6, 2, 5, 4.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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