From the FDA Drug Label
For the following infections, a dosage of 500 mg may be administered every 12 hours: ... uncomplicated cystitis in patients over 15 years of age. Cystitis therapy should be continued for 7 to 14 days. The recommended dosage of cephalexin for a 70-year-old female with uncomplicated UTI is 500 mg every 12 hours. The treatment should be continued for 7 to 14 days 1.
From the Research
For a 70-year-old female with uncomplicated UTI, I recommend nitrofurantoin as the first-line treatment, not cephalexin, due to its efficacy and lower risk of promoting resistance, as suggested by the most recent and highest quality study 2. The dosing for nitrofurantoin is typically 100 mg twice daily for 5 days. This recommendation is based on the latest guidelines and evidence that prioritize the use of nitrofurantoin for uncomplicated UTIs due to its effectiveness against common uropathogens and its lower propensity to contribute to antibiotic resistance compared to other options like cephalexin or fluoroquinolones 2, 3. Key considerations include:
- Confirming the absence of complicating factors such as pyelonephritis or structural abnormalities before initiating treatment.
- Ensuring the patient completes the full course of antibiotics even if symptoms improve quickly.
- Advising the patient to stay well-hydrated and to contact the healthcare provider if symptoms worsen or fail to improve within 48-72 hours, as this may indicate resistance requiring a different antibiotic.
- Being aware of potential side effects and the importance of renal function in drug clearance, particularly in elderly patients. Given the increasing rates of antibiotic resistance, the choice of antibiotic should be guided by local resistance patterns and the specific patient's risk factors for resistance, as highlighted in the study 2. It's also important to note that while cephalexin can be an effective treatment for UTIs, the most recent and highest quality evidence supports the use of nitrofurantoin as a first-line option for uncomplicated cases 2. In cases where nitrofurantoin is not suitable, alternative treatments such as fosfomycin or pivmecillinam may be considered, based on the patient's specific situation and local resistance patterns 2.