Diarrhea Incidence with Nitrofurantoin
Approximately 5-6% of patients experience diarrhea as a side effect when taking nitrofurantoin. 1, 2
Gastrointestinal Side Effects of Nitrofurantoin
Nitrofurantoin is commonly used for treating and preventing urinary tract infections, but like many antibiotics, it can cause gastrointestinal side effects:
- Diarrhea is reported in approximately 1-3% of patients in clinical trials, though some studies report rates up to 5-6% 1, 2
- Nausea is more common than diarrhea, occurring in 2-3% of patients taking nitrofurantoin 1
- Gastrointestinal symptoms typically occur early in the treatment course and are usually mild to moderate in severity 3
Comparison with Other Antibiotics
- Nitrofurantoin has a lower incidence of diarrhea compared to many other antibiotics used for UTIs 3
- In comparative studies, nitrofurantoin showed fewer gastrointestinal side effects overall compared to other antibiotics, with diarrhea specifically occurring in about 1% of patients (compared to similar rates with fosfomycin) 1, 2
- The most common adverse effects with nitrofurantoin are nausea and headache rather than diarrhea 4
Factors Affecting Diarrhea Risk
- Higher doses of nitrofurantoin (100 mg) are associated with increased risk of gastrointestinal side effects compared to lower doses (50 mg) 5
- Extended treatment courses may increase the risk of adverse effects, including diarrhea 6
- Taking nitrofurantoin with food can help reduce the incidence of gastrointestinal side effects, including diarrhea 3
Clinical Management Considerations
- Most cases of nitrofurantoin-associated diarrhea are mild and self-limiting, rarely requiring discontinuation of therapy 2, 3
- Severe or persistent diarrhea occurs in <1% of patients taking nitrofurantoin 1, 2
- If diarrhea develops, patients should be monitored for signs of dehydration, especially in elderly patients or those with comorbidities 3
Comparative Incidence
- Diarrhea incidence with nitrofurantoin (1-6%) is significantly lower than with many chemotherapeutic agents, which can cause diarrhea in 30-50% of patients 7
- The risk of diarrhea with nitrofurantoin is lower than with fluoroquinolones and comparable to fosfomycin 1, 2
When prescribing nitrofurantoin, patients should be informed about the possibility of diarrhea as a side effect, but reassured that it is relatively uncommon compared to other antibiotics and typically mild when it does occur.