There is a growing and increasingly robust evidence base for non-antibiotic prophylaxis of recurrent UTIs (rUTIs) in women. Here's a summary of the key options and their evidence:
<keypoints> - **Vaginal oestrogen** (postmenopausal women): strongest non-antibiotic evidence; reduces rUTIs by ~50-75% vs placebo; recommended as standard of care - **Cranberry products**: ~25% reduction in rUTIs (Cochrane 2023); moderate recommendation in AUA/CUA/SUFU 2025 guideline - **Methenamine hippurate**: non-inferior to daily prophylactic antibiotics in the ALTAR trial (RCT, n=240); with lower overall antibiotic use and antimicrobial resistance - **D-mannose**: recent JAMA RCT found it may not be effective alone; AUA 2025 now recommends informing patients of this - **Increased water intake**: 50% reduction in rUTI episodes in low-volume drinkers (<1.5L/day) who increased intake by 1.5L/day - **Immunomodulation**: pooled data show patients ~50% more likely to remain cystitis-free at 6-12 months (NNT ~6.5), but heterogeneous evidence </keypoints>Vaginal Oestrogen (Postmenopausal Women)
This has the strongest evidence among non-antibiotic options for postmenopausal women. The AUA/CUA/SUFU 2025 guideline gives a moderate recommendation (Grade B) to recommend vaginal oestrogen therapy in perimenopausal and postmenopausal women with rUTIs. A meta-analysis of eight studies (~5,000 women) found vaginal oestrogen significantly reduced rUTIs compared to placebo (RR 0.42). An RCT comparing vaginal oestrogen to placebo showed significantly fewer women experienced a UTI within 6 months (50% vs 94%, p = 0.041), with the oestradiol ring appearing particularly effective (38% vs 91%). Importantly, oral oestrogen has not shown benefit.
Mechanism: oestrogen increases glycogen in vaginal mucosa, promoting Lactobacillus colonisation, lowering vaginal pH, and inhibiting uropathogen growth.
Cranberry Products
The AUA/CUA/SUFU 2025 guideline gives a moderate recommendation (Grade B) to offer cranberry for prophylaxis. A 2023 Cochrane review found cranberry products reduced rUTI risk by approximately 25% in certain groups including women. The EAU also recommends cranberry to prevent recurrent cystitis, citing a favourable benefit-harm profile. Proanthocyanidins (PACs) prevent adherence to uroepithelial cells.