Research led by Newcastle Hospitals has found that an antiseptic drug is as good as antibiotics for preventing recurrent urinary tract infections in women. The trial, published by the British Medical Journal (BMJ), could help find alternatives to antibiotics.
The drug, called methenamine hippurate, sterilises urine, stopping the growth of certain bacteria. Previous studies have shown that it could be effective in preventing UTIs, but the evidence is inconclusive and further randomised trials are needed.
Over half of women have at least one urinary tract infection (UTI) in their lifetime, and recurrence (defined as at least three repeated infections per year or two infections in the preceding six months) occurs in about a quarter of women who have one episode.
Preventing recurrent UTIs
Current guidelines recommend daily low dose antibiotics as the standard preventive treatment for recurrent UTI. But such long term use of antibiotics has been linked to antibiotic resistance, so research into non-antibiotic alternatives is urgently needed.
Professor Chris Harding, consultant urological surgeon at Newcastle Hospitals and honorary clinical senior lecturer at Newcastle University, led the study working with colleagues to test if methenamine hippurate is an effective alternative to standard antibiotic treatment for preventing recurrent UTI in women.

Women were recruited from UK secondary care centres between June 2016 and June 2018 and were randomly assigned to daily antibiotics (102 women) or daily methenamine hippurate (103 women) for 12 months, with three monthly assessments up to 18 months.
Findings are based on 240 women (aged 18 or over) with recurrent urinary tract infections requiring preventative treatment. On average, before trial entry, these women experienced over six UTI episodes per year.
Credible alternatives
During the 12 month treatment period, the UTI rate was 0.89 episodes per person year in the antibiotic group and 1.38 in the methenamine group – an absolute difference of 0.49 episodes per person year.
This small difference between the two groups was less than the predefined threshold of one UTI episode per year, suggesting that methenamine was no worse than antibiotics at preventing UTIs.
Methenamine was also associated with reduced antibiotic consumption and similar levels of adverse reactions and treatment satisfaction compared to daily antibiotics.
And results were similar after further analyses, such as excluding days taking antibiotics for urinary tract infection, adding weight to the findings.
Commenting on the trial, Prof. Harding said:
“The outcomes of this trial could support a change in practice in terms of preventive treatments for recurrent UTI and provide patients and clinicians with a credible alternative to daily antibiotics, giving them the confidence to pursue strategies that avoid long term antibiotic use.
“We hope that the information provided by this trial might encourage patients and clinicians to consider methenamine hippurate as a first line treatment for UTI prevention in women. “
Important conversation
Researchers point out that data regarding long term safety of methenamine hippurate are scarce, and acknowledge some trial limitations, including lack of blinding and differences in antibiotics prescribed, that may have affected results.
Four participants allocated to methenamine hippurate were admitted to hospital because of UTI, and six participants who were allocated to methenamine hippurate reported a fever during a UTI episode (febrile UTI).
However, this was a well-designed trial that accurately represented the broad range of women with recurrent UTI seen regularly in routine NHS practice.
Prof. Harding added:
“Decisions on preventive treatment for recurrent urinary tract infection are well suited to shared decision making between each patient and their doctor, and will hopefully help to inform this important conversation.”