Summary: For women with recurrent cystitis, taking D-mannose (2 g of D-mannose daily for 6 months) may be just as effective at preventing another episode of cystitis as taking nitrofurantoin (50 mg daily for 6 months) but with a lower risk of side effects (and potentially without the risk of inducing antibiotic resistance, although this was not directly addressed in this study).

Strength of Recommendation = B